Science vs popular psychology, common vs. uncommon sense
-most of everyone‟s psychology knowledge comes from the popular psychology industry-
a sprawling network of everyday sources of information about human behavior
1.1 Although common sense can be enormously useful for some purposes, it‟s sometimes
1.2 – Naïve realism, seeing is believing – or is it?
We trust our common sense because we are subject to naïve realism – we believe that the
world is exactly as we see it. However our common sense is not always wrong, such as
that happy employees generally do a better job.
1.3 – Growth of popular psychology, many people have psychology however this leads to
a misinformation explosion. Self help and the media – 3500 self help books are published
yet only a small amount is published or screened by experts. Many psychology sites on
the Internet are not accurate and may cause people to become further misinformed. Also
there are plenty of psychics, however when they are put to the test none of them can
replicate any results. Quick fixes – substantial amount of new emerging psychotherapies
remain untested, and thus could be potentially unhelpful or harmful. We must exercise
caution when hearing about cures rather than treatments. Often we cannot deduce what is
popular psychology information and misinformation. We must be open to claims
however we must insist on evidence.
Psychology as a science – modern psychology is a science although it is usually found to
be a misconception amongst people. Science is actually an approach to evidence- toolbox
of skills designed to prevent us from fooling ourselves.
Communalism – willingness to share our finding with others since scientists are a
community of people that work together.
Disinterestedness – scientists should try their best to be objective when evaluating
evidence, however this is hard because all humans tend to be biased in some way. The
best scientists are aware of their biases or aware that they have them. They may even
bias the results unintentionally to make them turn out the way they want.
Confirmation Bias: science is a set of tools for overcoming confirmation bias, the
tendency to seek out evidence that supports our hypothesis and neglect of distort
evidence that contradicts them. (you will see what you are looking for). What makes
confirmation bias so important is that it extends to myriad domains of our daily lives. In
political elections it was found that most people forgave their candidate of choice for
contradicting themselves whereas they scrutinized the opposing one quite heavily. This
is the bias that can most easily fool us into seeing what we want to see and thus is the bias
that scientists most need to counteract. Scientists must be most careful when they are
emotionally involved in their studies since they can easily become blinded by their
results. Can lead psychologists to create studies to confirm their theories rather than
disconfirm them which is a poor way of doing science.
Belief Perseverance: it‟s my story and I‟m sticking to it – sticking to your story even
when the science disproves it. Good scientist will recognize that they are wrong or partly
off base even though they are attached to the project and hypothesis. News media also
often give the wrong headlines and misconstrued information about studies. Scientists
rarely use the words prove they tend to stick to the data suggests. - Some explanations that are considered better simply are better because they‟re
better supported by the evidence.
- Learning to thing like a scientist is merely just a way of minimizing errors.
1.5 Scientific Skepticism (“to consider carefully”)
- We must keep an open mind to all claims and not accept them until researchers have
subjected them to careful scientific tests.
- Should not be confused with pathological skepticism, which is a closed mindedness.
- Disconfirmation bias: the tendency to seek out evidence inconsistent with a
hypothesis we don‟t believe and neglect evidence consistent with it. We need open
mindedness but we must make sure we don‟t take it too far.
- Wegener‟s story remind us that we shouldn‟t automatically discount new ideas
merely because they seem implausible. (earth is round not falt)
- unwillingness to accept claims on the basis of authority alone. However most of us
place a good deal of weight on what authority figures tell us, although that is not
1.6 Basic principles of critical thinking
- Scientific skepticism is characterized by critical thinking, to evaluate all claims in an
open minded fashion. Critical thinking can help us overcome our confirmation biases
which can blind us to evidence we‟d prefer to ignore.
CT Principle #1 – extraordinary claims require extraordinary evidence
- The more a claim contradicts what we already know, the more persuasive the
evidence for this claim needs to be before we can accept it. i.e. alien abductions.
We must always ask ourselves is the evidence as extraordinary as the claim, does
it run against multiple things we already know?
CT Principle #2 – Falsifiability
- For a claim to be meaningful it must have the capability of being disproved – it
could be proved wrong if there were certain evidence against it. A good scientific
theory must predict only certain outcomes not others. (I.e hockey games all
resulting in a win or loss – nothing is being predicted). Many of Freud‟s theories
are hard to falsify.
CT Principle #3 – Occam‟s Razor
- If two explanations account equally well for a phenomenon, we should generally
select the more parsimonious one (simpler). Ie. Crop circles.
- Ask ourselves whether this is the simplest explanation, is there another
explanation that is simpler and accounts for the data equally well
CT Principle #4 – Replicability
- A study‟s findings can be duplicated consistently. If they cannot, the findings
could be due to chance. Media will not often print failed replicability, they will
print about a new and upcoming find.
CT Principle #5 – Ruling out Rival Hypothesis
- We must ask ourselves is this the only good explanation for the finding. We need
to ask whether we‟ve excluded other plausible explanations for the claims
CT Principle #6 – Correlation isn‟t Causation
- Misconceptions that things that are associated with one another are also causing
one another. However correlation isn‟t causation, and when we assume that this is true we are committing the correlation, causation fallacy. There can very well
be a third variable that causes both outcomes a and b that were previously thought
to cause each other.
1.6 What is Pseudoscience?
- An imposter of science is pseudoscience: a set of claims that seems scientific but is not,
lacking safeguards against confirmation bias and belief prevalence. The difference
between science and pseudoscience is not always clear-cut, sometimes it can be a
combination of the two.
Metaphysical claims: assertions about the world that are falsifiable such as about the
existence of God, the soul and the afterlife. These claims fall outside the boundaries of
science because falsifiability is key in scientific research. Science does have its limits
1.7 The prevalence of Pseudoscience beliefs
There are a handful of people that believe that there are ghosts and aliens and haunted
houses, however it is a problem that Canadians appear convinced that such claims are
correct even though the scientific evidence for them is essentially nonexistent.
1.8 Seven deadly sins of pseudoscience: useful warning signs
The more deadly sins that are present, the better we can say something is pseudoscience.
1. Ad hoc immunizing hypothesis – just an escape hatch that defenders of a theory
use to protect their theory from being falsified. When there are negative findings
they are presented in the form of a loophole however you can “see right through
them”. If they are constantly finding excuses for negative findings, they are
2. Lack of self-correction – Many science claims turn out to be wrong, and they tend
to be weeded away. In pseudoscience, they incorrect claims never seem to go
away because their proponents cling to them stubbornly despite contrary
3. Exaggerated claims: promise remarkable or dramatic cures but rarely deliver.
Such as the speed reading course that apparently can make you read up to 15
times faster. They say that it is proven to work, but when something is „proven‟
we must be skeptical because scientific knowledge is rarely conclusive.
4. Overreliance on anecdotes – A mountain of numerous anecdotes may seem
impressive but it shouldn‟t persuade us to put much stock in others‟ claims. It is
second hand evidence, „I know a person who‟. It is known that Pseudosciences
tend to rely heavily on anecdotal evidence, or on things that happened to one or
two people. Anecdotes are limited in three major ways.
- Anecdotes don‟t tell us anything about cause and effect, other factors may be
responsible for the extraordinary claims
- Anecdotes don‟t tell us anything about how representative the cases are. Usually
it is one in a million people that have a change, but we don‟t get to see the rest of
- Anecdotes are difficult to verify. How do we know that what is being said is
actually true. We have to have accept the claims on faith alone, which has no
place in science
Anecdotes are difficult to interpret as evidence. 5. Evasion of peer review – where experts in the field carefully screen the work of
their fellow scientists. Before work is published it goes to a panel of researchers
from other universities, who decide whether this is worthy of publication.
Sometimes its not published and sometimes it is but always with revisions that
need to be made. It is the best system we have for weeding out problematic
research. Pseudoscientists avoid the peer review process and conduct their studies
„in house‟ which are close to worthless. Peer review provides at least a minimal
quality-control safeguard against bas research.
6. Absence of connectivity: connectivity refers o the extent to which a researcher‟s
findings build on or “connect up with” previous scientific finding. Science is
mostly cumulative, new findings build on older ones. Pseudosciences neglect
previous research and purport to create grand new ideas out of the blue. Speed
reading courses lack connectivity with previous studies about the human eye.
7. Psychobabble – skeptical of claims accompanied by oodles of psychological or
neurological language. Designed to impress gullible readers who lack knowledge
in the field. Some claims mimic the style of scientific claims but possess little of
1.10 – 1.12 Why are we drawn to pseudoscience?
One clue comes from Epstein who proposed that our brains operate in two very
difference modes of thinking: rational and experimental (thinking with the brain vs. with
the heart). Rational thinking relies on careful reasoning and an objective analysis of the
evidence at hand. Slow and effortful because we must take the time to evaluate
evidence. Experimental thinking depends on intuitive judgments and emotional
reactions. Fast and effortless because we make it up on the spot. Experimental
thinking is our default mode of operating; we fall back on it unless we are forced to do
otherwise. Both modes are invaluable in every day life and we need both to function
successfully. If we use our experimental thinking too often, we can find ourselves subject
to pseudoscientific beliefs because we base it on gut level inferences and thus can
mislead us when evaluating scientific questions.
Motivational factors – pseudoscientific beliefs are so appealing because they serve a
powerful motivational function and they give us hope. We have plenty of reasons to feel
anxious in everyday life, and leave us vulnerable.
Transcendental temptation: the desire to alleviate out anxiety by embracing the lofty
promises of the supernatural. Believing in ghosts is scary, but relieving because we will
continue to live on. These things can eventually lead us to pseudoscientific beliefs, which
in turn also fulfill our deep-seated need for wonder. Our need for wonder can override
out critical thinking skills, leading us to accept claims for which there‟s minimal
Scientific illiteracy – Another reason for the belief of pseudoscience is the publics
overall lack of knowledge of science. Most Americans don‟t know that the earth takes a
year to fully revolve around the sun, and many think that dinosaurs and humans
Cognitive Factors – Making sense out of nonsense. Out brains are always on the
lookout for patterns to make sense of what‟s going on. Our brains are predisposed to
make order out of disorder and find sense in nonsense. This adaptive tendency can lead
us to find patterns where none exist. The interpreter: Michael Gazzaniga contended that the human brain especially out left
hemisphere functions as an interpreter, finding meaning in random data, and make sense
of the world, however sometimes It goes beyond the information it receives, detecting
nonexistent patterns. (eg dots on the top of the screen and rats). Sometimes people are too
smart for their own good.
Pareidolia: I‟ll see it when I believe it – the tendency to perceive meaningful images in
meaningless visual stimuli. (looking at a cloud and seeing an animal).
Apophenia: what a coincidence – The tendency to perceive meaningful connections
among unrelated phenomena. We haven‟t talked to a friend in months and then all of a
sudden they call, we think that this is related to ESP. We fail to recognize the amount of
times that we think about an old friend and they do not call. Coincidences are
everywhere, they are easy to detect if we look for them. Without convincing evidence to
the contrary it is usually more parsimonious to conclude that coincidences are attributable
to chance rather than to supernatural influences.
The hot hand: Reality or illusion? – It certainly seems as though basketball players go on
streaks. Do they? Researchers looking at the role of the 76ers have found that there is no
correlation between making a few hits improving your chances at having more hits, if
anything there is a higher probability that you will do worse.
1.13 Logical fallacies in psychological thinking.
Logical fallacy – traps in thinking that can lead to mistaken conclusions and it is easy
because they seem to make sense. Scientific thinking needs us to cast aside our intuitive
thinking which is usually hard to do.
Emotional Reasoning Fallacy – the error of using our emotions as guides for evaluating
the validity of a claim. We shouldn‟t make the mistake of not believing a claim just
because it makes us uncomfortable.
Bandwagon Fallacy – the error of assuming that a claim is correct just because many
people believe it. The amount of people that believe something as true does not an
accurate assertion of its truth.
Either-or Fallacy – the error of framing a question as though we can answer it in only
one of two extreme ways. E.g. that schizophrenia is due to either environment or solely
genetic inheritance – however there are many different things that can al together lead to
Not Me Fallacy – the error of believing we‟re immune from errors in thinking that afflict
other people. If can get us into trouble because we believe that we do not need the
scientific method. They believe their claims are so right that they do not bother to
conduct any studies to back up these claims.
Bias blind spot - which means that most people are unaware of their biases but keenly
aware of them in others.
1.14 The dangers of pseudoscience: why should we care?
Opportunity cost: what we give up – pseudoscientific treatments for mental disorders
can lead people to forgo effective treatments. Opportunity cost: people who invest time,
effort and energy in obtaining a questionable treatment may forfeit the chance to obtain a
treatment that works.
Animal deaths and extinctions: an unappreciated cost – pseudoscientific medical
treatments have resulted in the deaths of untold numbers of animals and even brought
them to extinction. Hunters have eliminated the black rhino in Africa because its horns fetch a pretty penny in the Far east. The horns are group and apparently cure fevers,
sexual dysfunction, even though there is no evidence to support theses claims.
Direct harm. Treatments can occasionally cause death. Like Candice and the rebirthing
procedure that apparently fixes behavioral problems, after being unwrapped from her
session she was dead.
The inability to think critically as citizens - If we are not careful, an inability to think
critically about a seemingly unimportant domain, like astrology can easily spill over to an
inability to think critically about issues that can crucially affect out planet‟s future, not to
mention our own futures and those of our children.
Facilitated communication, helped children with autism communicate with their parents,
however it was later found that the words being typed were not what the child was
thinking but more so what the facilitator was thinking or seeing, thus proving to be a
Research designs: Without research designs even intelligent and well-educated people
can be fooled. Scientific method is a bunch of tools that helps us avoid being tricked by
our own biases. Common sense and experience are limited for the purposes of testing
hypothesis. We need rigorous research methods to find out whether a technique really
works. Experience can be a good starting point however if it is not sufficient against
conformation bias and other human error.
Another example – prefrontal lobotomy where fibers were severed to treat schizophrenia,
doctors relying on subjective impressions – observed that patients get better after the
procedure – however that was not true.
Heuristics: mental shortcuts of rules of thumb that help us streamline our thinking and
make sense of the world. We are all lazy and try to conserve mental energies by
simplifying the world, we do not expend any more thinking than is necessary. Heuristics
occasionally can get us into trouble, by over simplifying reality. Daniel kahneman and
amos tversky pioneered the study of heuristics, showing that most of us behave
irrationally in many domains in our lives.
Representativeness: we judge the probability of an event by its superficial similarity to a
prototype. (matches a stereotype, judging a book by its cover). This strategy usually
works in everyday life. However sometimes it fools us because we relying too heavily on
the the superficial stereotypes ( representativeness heuristic), and neglecting the base
rate- how common a behavior of characteristic is.
Availability: estimate the likelihood of an occurrence based on the ways with which it
comes to our minds “ off the top of your head” guessing.
Confirmation bias: natural tendency to seek out evidence that supports our hypothesis
and to ignore, downplay of distort evidence that doesn‟t. Scientific method makes us less
likely to fool ourselves.
Hindsight Bias: Our tendency to overestimate how well we could have successfully
forecast known outcomes. Where common wisdom seems to appear correct. Overconfidence: tendency to overestimate our ability to make correct predictions. We
can‟t all be above average, but we all think we are. Found that for the questions we get
wrong, we‟re much more confident than we should have been that we got them right.
Heuristics and biases can make us certain we‟re right even when we‟re not, and make us
draw false conclusions and become convinced by them.
Scientific method is a toolbox of skills designed to counteract our tendency to fool
ourselves. They test hypothesis, which are specific predictions.
Naturalistic observation: watching behavior in real world settings. By doing so, we can
better understand the range of behaviors displayed by individuals in the real world as well
as the situations in which they exhibit them. Compared to a laboratory where their
reactions would be affected by their changed environment. Major advantage of
naturalistic designs is that they are often high in external validity: the extent to which we
can generalize our findings to real-world settings. However they tend to be low in
internal validity, the extent to which we can draw cause and effect inferences.
Case study: research design that examines one person or a small number of people in
depth often over an extended time period.
Advantages: can be helpful in providing existence proofs, demonstrations that a given
psychological phenomenon can occur (e.g. recovered memories of child abuse). Also
provide a valuable opportunity to study rare or unusual phenomena that are difficult of
impossible to recreate in the lab. (e.g. rare brain damage, dog fucker). Also offer useful
insights that researchers can later test in systematic investigations.
Disadvantages: If were not carful they can lead to misleading, even disastrously wrong
conclusions. Cannot determine cause and effect, and have troubles generalizing the
results to a broader population. Psychologists are cautious about relying on them to draw
Examine the extent to which two variables are associated, and to which they relate to
each other statistically.
- Can be positive, one goes up the other goes up, zero, variables don‟t go together,
or negative, one goes down the other goes down.
- Range in value from -1.0 to +1.0, where a -1.0 is perfectly negative and 1.0 is
- To find out how much of one variable is accounted for by another variable we
square the correlation.
Scatterplot: grouping of points on a 2D graph. Unless a correlation is perfect, there will
always be exceptions to the general trend.
Illusory Correlation: a statistical association between two variables where none exists.
We are very prone to this kind of behavior. (e.g. full moon and strange occurrences)
+Superstition: Illusory Correlations form from superstitions. We are all susceptible to
these illusions. We focus a lot of our attention on the ¼ times our expectation does come
true called the fallacy of positive instances because we‟re committing the error of homing
in on occurrences that match what we expect to find. These things are memorable and
interesting. We don‟t tend to remember nonevents, things that don‟t happen. Our uneven
attention causes us to imagine illusory correlations. A way to dismiss this is to start keeping track of when these things do correlate and thus giving the other three spaces in
the table (pp76) a chance.
We cannot determine causation from correlation. Most often two scenarios are due to a
third variable (e.g. mules and PhD‟s)
Experiments allow us to observe cause and effect relationships. They are manipulating
variables to see whether these manipulations produce differences in participants‟
An experiment consists of two things, Random assignment of participants to conditions
and Manipulation of an independent variable.
Random assignment – random assortment of two groups, one of which receives the
manipulation and the other does not thus being referred to as the control.
Manipulation: Independent variable: what the experimenter manipulated, and the
dependent variable is the variable that the experimenter measures to see whether this
manipulation has had an effect.
Confounds: there must be only one thing that differs in the two groups for the
experiment to be considered valid. The confound is any differences between the
experimental and control groups other than the independent variable.
Placebo Effect: Improvement resulting from the mere expectation of improvement.
People who receive a drug may get better just because they know they are receiving
treatment. It is critical that patients not know whether they‟re receiving the real
medication or a placebo, and that they remain blind to the condition which they‟ve been
assigned. If they are not blind to which group they are in, the experimental group might
improve faster and better because they know their pill is fake, and people in the placebo
group may want to beat the competition and get better faster. Placebo‟s have effects just
like real drugs, people sometimes even get addicted to placebo‟s. They are more effective
on things such as pain and depression than on heart attack and cancer type illnesses.
Nocebo Effect: Harm resulting form the mere expectation of harm. (e.g. students getting
headaches from a fake electric current running through their heads) This shows us that
expectations can become reality however in this case it is negative.
Experimenter expectancy effect: researchers‟ hypothesis leads them to unintentionally
bias the outcome of a study. Double blind is put into act where neither the experimenter
nor the participants know who is in the control vs. experimental groups and thus
shielding them from confirmation biases.
Hawthorne effect: Participants knowledge that they‟re being studied can affect their
behavior. The mere act of observing participants can influence their behavior.
- Demand characteristics are cures that participants pick up from an experiment that
allow them to generate guesses regarding the experimenter‟s hypothesis. If
participants know in which way the experimenter wants them to act they may
alter their behavior accordingly.
- Call that reactivity – people who know they‟re being studied may act differently
than they would otherwise.
Ways to minimize the effect: Cover themselves so that people don‟t know they‟re being
watched and participant observation where the investigator becomes a member of the
group and observe the other members in the group. Random selection: every person has an equal chance of getting selected and being chosen
Evaluating measures: when evaluating the results form any dependent variable or
measure, we need to ask two critical questions: is the measure reliable and is it valid.
Reliability refers to consistency of measurement, if the test is given again in two months
will it yield results that are 80% of the time similar?
Validity is the extent to which a measure assesses what it claims to measure.
Reliability is necessary for validity, we need to measure something consistently before
we can measure it well. Reliability is not sufficient for validity. Although a test must be
reliable to be valid, a reliable test can still be completely invalid. Something can always
be accurate however have nothing to do with what is being questioned, thus they are not
related and the fact that one is reliable has nothing to do with how valid that test is.
Self report measures and surveys: Able to asses a variety of characteristics and opinions,
however the way the questions are phrased plays an important impact on the outcome.
Sometimes the participants do not even understand the question being asked.
Self report measures are easy to administer, and they usually work fairly well.
Correlations tend to be higher for more observable traits such as extraversion rather than
anxiety. However these surveys tend to assume that respondents possess enough insight
into their own personality characteristics to report on them accurately( not applicable to
narcissistic self centered people). Also they tend to assume that participants are honest in
Two problematic things: positive impression management – tendency to make
ourselves look better than we actually are and malingering – the tendency to make
ourselves appear psychologically disturbed with the aim of achieving a clear cut personal
goal such as getting out of jail time.
Rating data: Alternative to asking people about themselves, asking people who know
them well to provide ratings on them. Although this has its drawbacks as well (pitfall
when interpreting ratings):
Halo effect – tendency of rating of one positive characteristic to spill over to influence
the ratings of other positive characteristics (an attractive person gets higher ratings on
things such as productivity).
Leniency Effect – tendency of raters to provide ratings that are overly generous( job
Error of Central tendency – an unwillingness to provide extreme ratings, such as
highest and lowest – can be overcome by giving an even number of options to choose
Ethical Issues in Research Design
Informed consent: researchers must tell subjects what they‟re getting into before asking
them to participate. Sometimes research ethics boards allow participants to be mislead
entailing deception, deliberate misleading about the nature of the study participants are
going to be involved in. (best known Stanley milligram at yale that lead his participants
to believe that they were giving others electrical shocks after answering a question
wrong). Deception may only be used when researchers cannot perform the study without the
deception, the use of deception of withholding the hypothesis does not negatively impact
the rights of the participant and the research does not involve a medial or therapeutic
REB‟s request that debriefing be present at the end of a study‟s completion, which is a
process whereby researchers inform participants what the study was about.
Ethical Issues in Animal Research
Goal of research on rodents is to generate ideas about how the brain related to behavior in
humans without having to inflict pain on them. Animals must be treated humanly and
there are many boards that ensure that happens. Many things would still be unknown
about the brain without animal research. Also, it would be very difficult to test any
medications‟ effectiveness without animal research.
Statistics: The Language of Psychological Research
Statistics: application of mathematics to describing and analyzing data.
Use two different kinds of statistics, descriptive stats that describe data and Internal
Descriptive: firstly central tendency, which gives is a sense of the “central” score in our
data set of where the group tends to cluster. These involve, mean, median and mode.
The three values can give us rather different measures of central tendency. Mean is
usually the best way to analyze data when it represents a normal distribution. When data
is skewed it is better to use median or mode.
There is also a descriptive stat called dispersion, which gives is a sense of how loosely or
tightly bunched the scores are. We can take into account the range of the highest and
lowest data point, however standard deviation is more reliable since it looks as each data
point in reference to the others.
Inferential stats: allow us to determine whether we can generalize findings from our
sample to the full population.
Statistical significance – use a 0.05 level of confidence to test whether the difference in
our sample is a real one, p<0.05, the probability of our finding occurring by chance alone
is less than one in 20.
Practical significance – a finding can be statistically significant but of no use to the real
world such as nose length correlating with IQ.
Peer review in psychological research
We must first consider the source when looking at the information provided, and also
place more trust in findings from primary sources such as original journal articles. We
should also beware of sharpening and leveling – exaggerating the gist or the central
message or minimizing the central details of a study. Media use balancing by using
„experts‟ from opposing sides.
Balanced coverage can create pseudo symmetry: the appearance of a scientific
controversy where none exists. Chapter 3
Phineas Gage accident with a large bar through his head that changed his personality.
Found that both sides of his prefrontal cortex were seriously damaged, and lead to
interest in how the brain affects behavior.
- Doctors who study he brain and behavior, biological psychologists or
Nerve cells: communication Portals
Workings of the brain depend on cross-talk among neurons, nerve cells specialized for
communication with each other. Brain: 100 billion neurons, 160 trillion connections in
the human brain
3.1 Neurons: The brain‟s Communication
Neurons have long branches or extensions that help receive and transmit information
Dendrites: Extensions for receiving information from other neurons called dendrites and
gradually taper from the cell body region, much as a branch on a tree narrows as it
extends outwards. Connections are directly with dendrites or small appendages on them
called spines, that transmit information to the cell body.
The cell body: or Soma, is the central region of the neuron and is responsible for the
maintenance of the cell. Responsible for integrating info from dendrites and passing it
along the axon.
Axon: Long extensions specialized for sending messages from one neuron to another,
very thin at their site of origin near the cell body. Length ranges to over a meter
Synapes: (Sir Charles Sherrington – Measured time it took for muscles to become active
following nerve stimulation) Synapse is a complex arrangement consisting of a synaptic
cleft, a gap into which neurotransmitters are released from the axon terminal. Other side
of the gap lie specialized patches of membrane called presynaptic and postsynaptic
membranes. A neuron released neurotransmitters from the presynaptic membrane and the
neuron that receives or detects the neurotransmitter does to through the post synaptic
membrane. Different proteins get integrated depending on whether they are sending or
Axon terminal: knoblike structure at the end of the axon, contained synaptic vesicles
(spheres that contain neurotransmitters) . Synaptic vesicles are constructed in the cell
body and travel down along the length of the axon, when they reach the axon terminal
they manufacture and accumulate high levels of neurotransmitter. Upon activation of
axon terminals, synaptic vesicles fuse with the presynaptic membrane and release
neurotransmitters into the synaptic cleft.
Glial Cells: serve as supporting actors in the nervous system and protect neuron, involved
in memory and learning. Certain ones respond to injury or release chemicals that promote
healing. Some form a fatty coating called the blood-brain barrier by wrapping around tiny
blood vessels. Some particles are simply blocked from enerting the brain, however
glucose enters by a special mechanism. protects itself from infection and high levels of
circulating hormones. 3.2 Electrical responses of neurons
Neurons respond to neurotransmitters by generating electrical activity, discovered by
electrodes which allowed them to measure the electrical charge across the neuronal
membrane. All electrical responses in neurons depends on an uneven distribution of
charged particles across the membrane. When the neuron is in a resting state, the negative
charges inside the neuron remain higher than on the outside resting potential
Action potentials: neurons contain and are surrounded by ions. Outside: sodium (+) and
inside is negatively charged protein and +K and the cell is surrounded by a selectively
permeable membrane. At rest, more positive sodium on the outside than K on the inside
are found. All these ions and proteins cannot permeate the membrane but when the
neuron is stimulated gates open that allow the +Na to enter the cell, which leads to a brief
reversal in the electrical charge o the axon and is called an action potential. These are
abrupt waves of electric discharge that allow neurons to communicate. Charge reversal
begins in the soma and moved down the axon. At the end of the axon are branches with
synaptic knobs that release neurotransmitters, which are chemicals that may inhibit or
excite another neuron. Gates that allowed Na in close, and membrane opens to allow K
ions to escape to restore the cell to resting potential leaving the neuron with a
temporarily greater negative charge. Sodium are returned to the outside and K to the
inside by a sodium potassium pump that actively transports the neurons across the
Action potential is all or none ( like a gun) and it is regenerative (once started the process
is self perpetuating) continues all the way down to the axon terminal. After each action
potential there is an absolute refractory period brief time during which another action
potential cant occur and limits the maximal firing rate. In some axons a myelin sheath
exists (glial cells) that wrap around the sending portion of neurons, which speeds up the
passage of electrical messages by insulating the neuronal signal. These same cells also
insulate the axons which prevents messages between axons from becoming scrambled. Ie.
Insulated electrical wiring no myelin sheath can result in MS because the messages do
not get relayed all the way down the axon. Action potentials hop from node to node
resulting in a more rapid relay than if the entire axonal membrane participated in
Graded Potentials: post synaptic potentials that can be excitatory or inhibitory depending
on whether positively or negatively charged particles flow across the neuronal membrane
and in which direction. Excitatory inputs and inhibitory inputs add together or cancel out.
When excitation prevails and reaches high enough level called the threshold and action
potential occurs. Whereas a graded potential can increase or decrease the likelihood that
an action potential will occur and action pot itself is all or none.
3.3 Chemical neurotransmission
Neurotransmitters orchestrate intercellular communication among neurons, by binding to
specific receptor sites that uniquely recognize a specific neurotransmitter. Think of a
neurotransmitter as a key that only fits its receptor or lock
1. Neurotransmitter releases from axon terminal into synaptic cleft
2. Binding neurotransmitter to receptor site 3. Halting neurotransmission by either the chemical breakdown of the
neurotransmitter or by reuptake into the axon terminal presynaptic neuron
reabsorbs the neurotransmitter.
Neurotransmitters: messengers with slightly different things to say. In the cerebral cortex
all these messages are integrated into perception and action.
Glutamate and GABA: most common NT in the CNS. Neurons in virtually every brain
area use these NT to communicate with other naurons. Glutamate excited, GABA inhibits
neurons dampening neural activity.
Acetylcholine: first substance to act as a NT. Is manufactured in the basal forebrain and
released in the cerebral cortex, plays a role in cortical arousal, selective attention and
memory and movement because of neurons that synapse onto muscle cells.
Monoamine NT: norepinephrine, dopamine and serotonin are the monoamine NT
because of their chemical structure. Schizophrenia elevated dopamine, Parkinson‟s
lower levels of dopamine. Low levels of norepinephrine and serotonin associated with
Neuropeptides: short strings of aa in the nervous system, have specialized roles.
Endorphins pain reduction, endogenous opioids, brains natural narcotics. Opiates
derived from the opium plant was used before we knew we had our own.
Anadamide: bodies make it and binds to the same receptors as THC, plays a role in eating
motivation, memory and sleep
Psychoactive Drugs: Drugs that interact with NT systems, they affect mod, arousal of
behavior in some way. Can be toxic at high doses e.g Botox causes paralysis by blocking
acetylcholine actions on muscles. Can be deathly is ingested. Opiate drugs are agonists –
they enhance receptor site activity. Reduce pain and emotional response to painful stimuli
by mimicking endorphin and binding to opioid receptors. Drugs function on certain NT
receptros, when they remain in the synaptic cleft longer than they should their effects are
enhanced. Tranquilizers stimulate GABA receptor sites reducing neuronal activity.
Antidepressants block the reuptake mechanism that removes serotonin, norepinephrine or
dopamine from the synaptic cleft.
Some drugs function in the opposite way called antagonists, decrease receptor activity.
Schizophrenia drugs block dopamine receptors by binding to them and thus blocking
usual effects of dopamine.
Our nervous system propels our body into action. Sensory information comes into and
decisions to act go away from the central nervous system (CNS) – brain and spinal chord.
Nerves that extend out – peripheral nervous system, PNS. PNS is divided into the somatic
NS which controls behavior and the autonomic NS which helps us experience and
Cerebrum or forebrain is the most developed area in the human brain and give us our
advanced intellectual abilities. Largest part is the cerebral cortex, which contains 12-20 billion neurons which analyzes sensory information and aids in the initiation of complex
motor functions. It is also responsible for thinking talking and reasoning.
The Neocortex: vast majority of our cerebral cortex. Not in birds and reptiles. In humans
it is able to attain a larger size in proportion to our bodies. Large band of fibres
connecting the two cerebral hemispheres is called the corpus callosum. Neocortex
contains 4 lobes, each with different functions.
Frontal Lobe: foreward part of the cerebral cortex containing the motor cortex and
prefrontal cortex. Responsible for motor function language and memory and executive
function. Deep groove called central sulcus separates the frontal lobe from the rest of the
Neocortex. Motor cortex lies next to the central sulcus. Each part of the motor cortex
controlled a specific part of the body. In front of the motor cortex is the prefrontal cortex,
responsible for thinking planning and language. Broca‟s area defect causes Broca‟s
aphasia characterized by difficulties in speaking smoothly and an inability to come up
with certain words. Prefrontal cortex serves additional functions including memory,
abstract thinking and decision making because it receives info from many other regions
of the cerebral cortex. Also contributes to mood personality and self awareness.
Parietal Lobe: upper middle part of the cerebral cortex lying behind the frontal lobe. Part
that lies beside the motor cortex is the somatosensory cortex devoted to touch. Sensitive
to pressure temp and pain and also plays a role in spatial perception, perception of object
shape and orientation, others actions, changes in attention and the representation of
numbers. Damage to parts of the left parietal lobe can cause acalculia: difficulty with
mathematics. Damage to the right can result in contralateral neglect, producing a
complete lack of attention to the left half of the body.
Temporal Lobe: site of hearing understanding language and storing autobiographical
memories. Separated from the rest of the Neocortex by lateral fissure. Top contains the
auditory cortex the part devoted to hearing. Language area is called Wernicke‟s area, and
damage to this results in difficulties with understanding speech, people with this usually
are just speaking nonsense and are unaware of their deficits. Lower part contains circuitry
critical to storing memories of autobiographical events.
Occipital lobe: Very back of the brain, containing the visual cortex. For each species the
amount of sensory cortex of each type is proportional to the degree to which it relies on
Cortical Hierarchies: Information from the outside world transmitted by a particular
sense reaches the sensory cortex, which is specific to a particular sense. Next, sensory
information travels to cortical regions that integrate simpler functions to perform more
complex functions, which are called association cortexes which play a role in perception
memory attention and conscious awareness.
The basal Ganglia: Two sets of structures in the forebrain that help to control movement
- works with the cerebral cortex, which after processing sensory info informs the basal
ganglia calculate a course of action and transmit that plan to the motor cortex. Also
responsible for making sure out movements help us obtain rewards, pleasurable activities.
Damage plays a key role in Parkinson‟s disease. Cells degenerate in an area of the
midbrain that pumps dopamine into basal ganglia, called substantia nigra.
Basal Forebrain: lower part interacts with the cortex when it comes to mental activities.
Selectivly activates different parts of the cortex allowing us to attend to some things and
ignore others. Manufacture acetylcholine and disperse throughout the cerebral cotex to stimulate movement memory selective attention and dreaming. Acetylcholine containing
neurons in the basal forebrain degenerate in patients with Alzheimer‟s disease
(dementia). Scientists have shown that acetylcholine loss correlates with intellectual
Thalamus: many areas each of which connects to a specific region of the cerebral cortex.
Gateway to the cerebral cortex.
Brain stem: connects with the forebrain and contains the medulla, midbrain and pons.
The midbrain: between the forebrain and the hindbrain. Contains the substantia nigra,
superior colliculus (controls tracking of visual stimuli) and inferior colliculus (controls
reflexes triggered by sound).
Reticular activating system: RAS, connects to the basal forebrain and the cerebral
cortex, plays a key role in arousal, and damage results in a coma. Pathways emanating
from the RAS activate the cortex by increasing the signal to noise ratio. E.g. ADHD, a
disorder originating in childhood, marked by inattention over activity and impulsivity.
Ritalin icreases the signal to noise ration in the prefrontal cortex.
The hindbrain: lies below the midbrain it consists of the cerebellum, pons and medulla.
Cerebellum is a miniature version of the cerebral cortex. Pons connect the cerebral cortex
with the cerebellum. Plays a predominant role in our sense of balance and enables us to
coordinate movement and learn motor skills. Medulla regulate breathing, heartbeat and
other vital functions. Damage to it results in a irreversible coma.
Cerebral ventricles: waterways of the SNA and extend throughout the entire brain and
spinal cord. Cerebrospinal fluid runs through the cerebral ventricles and bathes the brain
and spinal cord providing nutrients and cushioning against injury.
The spinal cord: contains all the nervous tissues needed for communicating between the
brain and the body as well as spinal reflexes. Nerves long extensions arising from
neurons travel in two directions. Sens info arrives by sens nerves and motor commands
exit the spinal cord by way of motor nerves. Sensory nerves bring info to spinal cord
about the sense of touch and the stretch of muscle fibres and originate from sensory
neurons, which lie next to the spinal cord. In spinal cord, sens neurons contact
interneurons that send messages to other neurons located nearby. Interneurons then
stimulate motor neurons which send messages through motor nerves which cause
muscles to contract.
3.6 The somatic nervous system
- carries messages from CNS to muscles controlling movement. Muscle contraction is our
only choice since we cant lengthen muscles directly. Muscles come in pairs that mobilize
a body part around a joint. Bend our arm at the elbow we contract the muscles
responsible for flexing the arm while we relax the muscles responsible for extending the
Specialized parts of the brain devoted to emotion
The Limbic System: emotional center of the brain, plays roles in smell motivation and
memory. Limbic structures aren‟t as well developed as neocortical systems ( hard to put
emotions in to words)
The Hypothalamus: maintains constant internal bodily states by overseeing the
endocrine and autonomic systems. Cnetered where the optic nerves cross from one side to the other. Most areas of the hypothalamus engage in multitasking. Primary function is to
The amygdala: Excitement, arousal fear are all part of the amygdalas job. Kicks in when
playing violent video games. In humans plays a role in recognition of fear. Recieves
information from neocortical centres that process cognitive and social information. Might
help us to learn that when our boss is in a good mood we are more likely to get a raise.
Cingulate Cortex: lies buries between the two cerebral hemispheres. Becomes active
when we express out emotions and like the hypothalamus it regulates the autonomic
nervous system. Contributes to social behavior and is necessary for learning how to act in
complex situations such as how to introduce out friends to one another.
Hippocampus: Spacial memory functions. Spacial cells in the hippocampus known as
place cells become active when an animal returns to a specific place in a familiar
environment. (large in experienced taxi drivers)
With the amygdala and the prefrontal cortex, also contributes to fear conditioning. When
confronted with fear the hippo interacts with these brain regions to integrate the
emotional significance of an event with its cognitive interpretation. By interpreting as
challenges we can reign our emotions. Damage to the hippo causes problems with
forming new memories but leaves old memories. Multiple trace theory memories are
initially stored at multiple sites. Over time storage strengthens at some sites but weakends
3.8 The autonomic nervous system
hypothalamus, amygdala and other limbic regions interact with the autonomic nervous
system to regulate emotion. There is the sympathetic and parasympathetic division which
work in opposing directions. When one division is active the other is passive.
Sympathetic: emotional arousal such as a crisis, fight or flight response, when an animal
encounters a threat the SNS becomes aroused and prepares the animals for fighting or
fleeing, by increasing heart rate respiration and perspiration.
Parasympathetic: is active during rest and digestion
3.9 The endocrine system
Regulates emotion, consists of glands that release hormones, blood borne molecules that
influence target tissues into the blood stream. Hypothalamus controls this system and
receives feedback from it
Pituitary gland and pituitary hormones: gland controls the other glands in the body and is
called the master gland. Two ways hormones get from the hypothalamus to the pituitary.
Neurons in the hypothalamus make vasopressin and oxytocin and secrete them directly
into the pituitary which releases these hormones into the bloodstream. Vasopressin
regulates water retention in the kidneys and oxytocin is responsible for stretching the
cervix and vagina during birth and for ejecting milk in nursing mothers. These two also
play roles in maternal and romantic love. Oxytocin may also be a key player in
interpersonal trust; in one study men exposed to a nasal spray containing oxytocin were
more likely than other men to hand over money to their team partners in a risky
investment game. Hypothalmic hormones control the pituitary gland in another way. Hormones get carried
to the pituitary and cause it to release pituitary hormones into the circulatory system
which trigger other gland throughout the body to release their respective hormones.
Growth hormone: is an exception in that it doesn‟t act directly on a gland. Released by
the pituitary acts directly on cells throughout the body causing them to grow and
determines height. Synthetic Growth hormone can help a child make up those extra
Adrenal glands and adrenalin: emergency cnetres, located on top of the kidneys and
manufacture adrenalin and cortisol sometimes testosterone. Boosts energy production in
muscle cells. Synaptic nervous system trigger the release of adrenalin by adrenal gland.
contraction of heart, opening of bronchioles, breakdown of TAG, breakdown of
glycogen, opening the pupils of the eye. Inhibits gastrointestinal secretions (sympathetic
arousal is incompatible with parasympathetic arousal). Allows people to perform
amazing feats under crisis situations although these acts are constrained under peoples
physical limits. Also secreted during pleasurable and exciting activities.
Cortisol: increases in response to physical and psychological stress. Regulated blood
preassure and cardiovascular function and the body‟s use of proteins, carbs and fats.
Sexual reproductive glands and sex hormones: testes and ovaries e.g. testosterone and
estrogen. We have more of our respective hormone, but we also have both. Most
researchers accept that testosterone regulated sex drive in males and in females to a lesser
extent. Australian researchers suggested that stress and fatigue decreased the womens
libido and that relationship problems affected their libido more than any other factor.
3.10 Mind brain identity
Mind and brain are one in the same. E.g. brain activity chances with different behaviors
and perceptions, brain damage causes deficits in behavior and perception, stimulating the
brain activates behavior and perception.
3.11 A tour of brain mapping methods
Phrenology: earliest methods that attempted to map mind onto brain. Examined the
heads and bumps of people and associated them with traits. Correctly predicted a positive
relationship between enlargements in specific brain areas and certain traits and abilities
but was wrong that enlarged bumps created impressions over the skull.
Brain damage: experimentally, scientists have created lesions, areas of damage in
experimental animals using stereotaxic methods, techniques that permitted them to
pinpoint the location of specific brain areas using coordinates much like those that
navigators use on a map.
Electrical stimulation and recording of nervous system activity: Fritsch and Hitzig were
the first to show that stimulating the cerebral cortex in an experimental animal caused
specific movements. Needed to test the hypothesis that the brain uses electrical activity
to send information. Hans berger developed the electroencephalograph, that measures the
electrical activity generated by the brain. Method has a high temporal resolution, meaning
it can detect changes in over all electrical activity of the brain occurring in the range of
milliseconds. However tell us little about what‟s happening in the neurons and have a low
spatial resolution. Brain Scans
CT scans and MRI images: computed tomography and magnetic resonance imaging. 3d
reconstruction of many x-rays taken through a part of the body such as the brain. MRI
measures the release of energy from water in a biological tissue following exposure to a
uniform magnetic field. MRI is better at detecting soft tissues such as brain tumors
PET: positron emission tomography, which is a functional imaging technique
measures changes in the brain‟s activity levels. Relies on the fact that neurons take up
glucose when they are more active. Use radiotracers to see where the most glucose like
molecules are taken up.
BOLD Response and fMRI: blood oxygenation level dependent response in 1990. As
neural activity picks up its pace there‟s an increase in oxygenated blood in response to
heightened demand and fMRI measures the change in blood oxygen level. fMRI operates
at a low resolution, and a sequence of images shows changes in time of brain activity.
Magnetic stimulation and recording
Transcranial magnetic stimulation(TMS) which applies strong and quickly changing
magnetic fields to the skull to induce electric fields in the brain. TMS can enhance or
interrupt brain functions. Can be a treatment for depression.
Magnetoencephalography (MEG) measures tiny magnetic fields and detects electrical
activity in the brain and the rest of the nervous system. Has a good special and temporal
resolution measuring activity changes millisecond by millisecond.
How much of our brain do we use:
The misconception that we only use 10% of our brains, it was shown that there is not
only one designated area for memory in the brain. We now know that every part of the
brain has its function and losses of small areas of certain parts of the brain can cause
devastating often permanent effects and losses of function. All brain areas become active
on brain scans at one time or another as we think, feel and perceive.
What parts of our brain do we use?
Localization of function is when sceintists identify brain areas that are active over and
above a baseline rate of activity during a psychological task. Just as multiple brain
regions contribute to each psychological function, individual brain areas contribute to
multiple psychological functions. Broc‟as area, is also active when we notice that a
musical note is off-key. Each brain region participates in many functions, some expected
some not, leading to a distributed set of brain regions contributing to each function.
Activity in different brain regions can be synchronized or not. EEG studies show that
synchronizes fast paced activity also called gamma frequency activity occurs during a
variety of tasks, including perception, attention and other higher cognitive functions.
Which side of our brain do we use?
Functions can be localized to left and right hemispheres. Two sides have different
functions and different levels of language ability. Examined in patients who underwent
split brain surgery for epilepsy by severing the corpus callosum, and this offers relief
from seizures. These people can exhibit different personalities and abilities. Right and left hemispheres
Cognitive functions rely on one cerebral hemisphere more than the other lateralization.
Many of the lateralized functions concern specific language and verbal skills. In a normal
brain, most visual information from either the left or right ends up on the opposite side of
the visual cortex. There‟s also crossing over from motor control, left controls right hand
and right controls left hand. The corpus callosum shares information between the two
halves or the cerebral cortex. Split brain subjects can experience decoupling of functions,
left hand doing strange things..
Consciousness and self awareness: one component is the ability to distinguish ourselves
from others. Left hemisphere seems to have an edge over its right-sided counterpart.
3.13 How we came to be who we are
Biological material of hereditary: humans have 46 chromosomes which are the slender
threads inside the cells nucleus that carry genes, genetic material. Genes are made up of
DNA, the material that stores everything cells need to replicate themselves. Double helix,
which unravels to allow mRNA to make reverse template. mRNA leaves the cells nucleus
and provides a sequence template for synthesizing proteins needed by the cell.
Genotype vs phenotype.
Behavioral adaptation: natural selection; populations of organisms rather than individuals
change by selective breeding with other organisms possessing some apparent advantage.
Some adaptations are behavioral, such as aggressive behavior because it enables
organisms to obtain more resources. Many successful adaptations have a high level of
fitness good chance of getting their genes passed on into later generations.
Brain evolution: brain regions with complicated functions like the Neocortex have
evolved the most thus our behavioral repertoires are more complex.
Humans and apes split off from a common ancestor. Humans have been around for only
about 1% of the total time period of the human race. Within a span of a few million years
one tiny area od the human genome responsible for protein synthesis in the cerebral
cortex changed about 70 times more rapidly than other areas. The human brain tripled in
size. Proportional to our size we are the biggest brained animals and then dolphins.
3.14 Behavioral genetics
- To examine the roles of nature and nurture in the origins of traits such as intelligence
- Behavioral genetic designs also allow us to estimate the heritability of traits and
diseases the extent to which genes contribute to differences in a trait among
individuals measured as a percentage out of 100.
-Heridability isn‟t a simple concept as it seems. Many misconceptions: that heritability
applies to a single individual rather than to differences among individuals. Actually it
tells is about the causes of differences among people, not within a person. Another,
misconception is that heritability tells us whether a trait can be changed. Can stop
watering plants and make their heights zero and their heritability change from 1000.
Third misconception is that heritability is a fixed number. Can however differ
dramatically across different time periods and populations. Behavioral genetic design: tracking the presence or absence of a trait among difference
relatives which help them determine how much both genes and environment contribute to
the causes of that trait.
Family studies: extent to which a trait runs in intact families.
Twin studies: if identical twins are more alike on a psychological characteristic such as
intelegence than are fraternal twins we can infer that this characteristic is genetically
influenced. Hinge on equal environment assumption, that the environmental influences
on the characteristic we‟re studying re the same in identical and fraternal twins.
Adoption studies: Examines the extent to which children adopted into new homes
resemble their adoptive as opposed to biological parents.
Genetic markers of disease: host of neurological disorders are strongly genetically
influenced. This is known as a DNA sequence that enables us to forecast the expression
of an illness that‟s at least partly heritable.
3.15 Neural Plasticity: how and when the brain changes
Ability of the nervous system to change is plasticity.
during Development and Experience : NS is most capable of changing during early
development and until maturation is complete. Period of heightened plasticity in the
human brain is lengthy. First step in neural development is an initial burst of cell
division, followed by migration and then by the establishment of connections among
neurons. 1. Growth of dendrites and axons, synaptogenesis – forming of new synapses,
pruning – death of certain neurons and retraction of axons (70%dies) and, myelination,
insulation of axons with a myelin sheath.
related to Learning: Simplest kind is for synapses to perform better, and it is called
potentiation, and long term potentiation. Exposure to enriched environments results to
structural enhancements to dendrites. The abuse of drugs can lead to detrimental changes.
Lead to stronger drug seeking behavior and decreased dendritic spine density in the
forebrain. Specific proteins determine the shape of neurons, dendrites and axons that also
enable NT to act. When animals are trained to learn certain associations there‟s a
reorganization of the major proteins in the dendrites, and those that participate in carrying
proteins to synapses enabling NT to act.
plasticity following injury and degeneration: Human CNS exhibits only a limited
degree of regeneration following injury. Neurons respond to chemicals called
neurotrophic factors that aid their survival and stimulate growth and grow an axon which
follows the trail of a neurotrophic factor. Also glial cell bridges that pave a way for the
axon and release neurotrophic factors along the way.
Stem cells: have the potential to become a wide variety of specialized cells. 1. Can
implant stem cells directly into the host‟s nervous system and induce them to grow and
replace damaged cells. 2. Genetically engineer stem cells so that the cells can administer
gene therapy provide replacement genes. 2. Allow scientists to aquire a better
understanding of how neurons age.
Neurogenesis: generation of new neurons withing the NS and already occurs in some
brain areas in the hippocampus and cerebral cortex. CHAPTER 4
Sensation: detection of physical energy by sense organs in the eyes ears, skin nose and
tongue, which then send information to the brain.
Perception: interpretation of these sensory inputs.
We often fill in that helps us make sense out of confusing and chaotic perceptual world.
We often mix illusory with sensory based information to arrive at perceptual decisions.
Blend the real with the imaginary to make sense of nonsense.
Transduction: The process by which the nervous system converts an external energy or a
substance into excitation or inhibition. Convert external energies to substances into
language the NS understands such as action potential. A particular type of sense receptor
transduces a specific stimulus. Sensory adaptation, at first the stimulus (sense) is strong
and then decreases.
Psychophysics: how we perceive sensory stimuli based on their physical characteristics.
- absolute threshold of a stimulus, lowest level of a stimulus we can detect on a 50
percent of trials when that stimulus appears by itself.
- Just noticeable difference is the smallest change in the intensity of a stimulus that
we can detect. Webers law says that there‟s a constant proportional relationship
between the JND and the original stimulus intensity. The larger the stimulus the
more we need to add to notice a difference
- Signal detection theory to help determine how we detect stimuli under uncertain
Specific nerve energies: sensation experienced is determined by the sense receptor not the
stimulus. These energies follow specific pathways up to the cerebral cortex and then
specific sensory pathways disperse throughout the cortex. Scientists have found many
examples of cross modal processing that produce different perceptual experiences than
either modality it provides by itself. McGurk effectwe integrate visual and auditory
info when processing spoken language, our brains calculate the most probable sound
given the info from the two sources. A single brain region may serve double duty,
helping to process multiple sences.
Parallel processing: we can attend to many sense modalities simultaneously. Bottom up
processing we construct a whole stimulus from its parts. Top down
processingdriven by our beliefs and expectations. Most often these two work hand in
Subliminal perception: processing of sensory information that occurs below the level of
conscious awareness, the claim is extraordinary but the evidence is compelling Subliminal persuasion: subthreshold influences over out product choices, votes in
elections and life decisions. Although it is not impossible it is unlikely in most cases.
Subliminal self help tapes are ineffective. Illusory placebo effect: subjects did improve
but not for the correct reason. Phil Merikle found that many of these tapes have no
message at all.
Our mind doesn‟t rely only on what‟s out there in the sensory field but it pieces together
what‟s in the sensory field along with that was just there a moment ago and what we
remember form our past.
P Sets: Relation between a stimulus and its context and we tend to organize information
into these sets by grouping things together that go together. Things we take for granted
alter our perceptions, an apple will always look red.
P. Constancy: the process by which we perceive stimuli consistently across varied
conditions. There is shape size and colour constancy, eg person even though walking
away will always be pictured as the same size and fire fighters yellow jackets are always
bright yellow no matter how dim the light is.
Selective attention: allows us to select one channel and turn off ther others or at least
turn down their volumes. This is done by the reticular activating system RAS and the
basal forebrain. Filter theory of attention views attention as a bottleneck through which
information passes. This enables us to pay attention to important stimuli and ignore
others. Shadowing: repeating what the messages that were heard. Cocktail party effect:
our ability to pick out an important message like our name in a conversation that doesn‟t
involve us. Thus the filter inside our brain which selects what will and wont receive our
attention is more complex than just on or off.
Binding problem: one of the great mysteries of psychology. How our brains take multiple
pieces of information and combine tem to represent something concrete like an apple.
Suggested that coordinated activity across multiple cortical areas does the trick.
Light: Form of electromagnetic energy composed of fluctuating electric and magnetic.
We respond to only a narrow range of wavelengths of light – human visible spectrum.
When light reaches an object part gets absorbed and part reflected. Brightness is the
intensity of the reflected light that reaches our eyes. Hue: colour of light and we are
sensitive to red green and blue.
4.3 The Eye
Sclera iris and pupil: Sclera is the white part of the eye. Iris is the coloured part usually
blue brown green or hazel responsible by pigments. Only two, melanin and lipochrome
are responsible for all eye colours. The iris controls the amount of light that enters our
eyes. Pupil is a circular hole through which light enters the eye and its closing is a
reflexive response. The dilation of the pupil also has psychological significance. They dilate when we are trying to process complex info, and when we view something
Cornea, lens and eye muscles: Cornea is curved transparent layer covering the pupil.
Curvature is responsible for bending light and focusing it on the back of the eye. Lens
also bends light but it changes its curvature, and consists of transparent cells.
Accommodation: the lenses change shape to focus light on the back of the eyes and adapt
to different lighting conditions.
Shape of the eye: nearsightedness (myopia) results in images that are focused in front of
the rear of the eye, due to our cornea being too steep or our eyes too long. Inability to
see far objects well. Farsightedness is an inability to see near objects well. As we age our
eyesight gets worse because the lens can accommodate and overcome the effects of most
mildly misshapen eyeballs until it loses its flexibility due to aging.
Retina: thin membrane at the back of the eye. Fovea is the central part of the retina and is
responsible for acuity, or sharpness of vision.
Rods and Cones: Rods, more plentiful enable us to see basic shapes and forms, and help
us see in low levels of light once the rods have regained their full sensitivity to light (dark
adaptation). Cones: colour vision, sensitive to detail but require more light than rods.
Receptor cells contain photopigments, chemicals that change following exposure to light,
photopigments in rods is rhodopsin and vitamin a is needed to make it.
Ganglion cells: contain axons, bundle together and depart the eye to reach the brain.
Blind spot: Region of the retina containing no rods and totally devoid of sense receptors.
This is because the axons of ganglion cells push everything else aside.
Optic nerve: contains the axons of ganglion cells, travels from the retina to the rest of the
brain. After the optic nerves leave both eyes they come to a fork called to optic chiasm,
where half the nerves cross it and the other half stay.
4.4 Visual perception
Handled by different parts of our visual cortex.
Perception of shape and contour: cells in the V1 respond slits of light of a specific
orientation. Simple cells display distinctive responses to slits of a specific orientation,
buit in a specific location. Complex cells are also orientation specific, but their responses
are less restricted to one location.
Feature detection: ability to use certain minimal patterns to identify objects that can
detect straight lines or be more complex to detect length of lines, and moving objects.
Visual information travels from V1 to upper and separately to lower parts of the parietal
lobe and temporal lobe resp.
Subjective contours: brains provide missing information about outlines.
Gestalt principles: visual perception entails a lot of analyzing an image in the context of
its surroundings and applying what we already know. These are rules governing how we
perceive objects as wholes within their overall context. Help to explain why we see much
of our world as unified figured or forms rather than as a confusing jumble of lines and
1. Proximity – two objects close together tend to be perceived as unified wholes.
2. Similarity – all things being equal, similar objects as comprising a whole
3. Good continuation – still perceive objects as wholes even if other obj block part 4. Closure: mind fills in what‟s missing when parts are present
5. Symmetry: perceive objects that are symmetrically arranges as wholes more often
then those who are not
6. Figure-ground: make an instant decision to focus our attention on what we believe
to be the central figure and largely ignore what we believe to be the background.
Which is an example of bistable images that we can percieve in two ways vase
Face recognition: we don‟t need the exact picture of a face to recognize it, because our
brains get by with only partial information. Lower part of the temporal lobe responds to
Motion perception: brain judges how things in our world are constantly changing by
comparing visual frames. Phi phenomenon is the illusory perception of movement
produced by the successive flashing of images, like flashing lights that seem to circle
around a movie marquee.
Colour perception: we use lower visual pathway leading to the temporal lobe to process
colour information but it hardly sits there.
- trichromatic theory: the idea that we base our colour vision on three primary
colours blue green and red and the theory that we have three different kinds of
cones each that pertains to a different wavelength of light
- according to opponent process theory, we perceive colour as either red or green or
as blue or yellow. Ganglion cells of the retina and cells in the visual thalamus that
respond to red spots are inhibited by green spots.
Depth perception: ability to see spatial relations in 3D, enables us to reach and grab
Monocular cues: we can perceive 3d using only one eye by using pictorial cues to give us
sense of what's located where. Done by: relative size, texture gradient, interposition,
linear perspective, height in plane, light and shadow. Not a pictorial cue is motion
parallax – the ability to judge the distance of moving objects from their speed.
Binocular cues: Half the axons in the optic nerve cross to the other side and half stay on
the same side before entering the brain.
- Binocular disparity, right and left eyes transmit quite different information from
near objects but see distant objects similarly. Each eye sees the world differently
and the brain uses this to judge depth
- Binocular convergence: when we look at nearby objects we converge our eyes to
focus on them, since our brains are aware of this the use te amount of
convergence to figure out the distance of the object
Depth perception in infancy: babies can judge depth and height even when they first
begin to crawl
When perception deceives us: The moon illusion the illusion that the moon appears
larger when its near the horizon than high in the sky. The Ames roomdistorted room is
actually trapezoidal. Insert two people of the same size into the room and it creates the
impression of a giant person on the side where the ceiling is lower and a tiny person on
the side of the room where the ceiling is higher.
Size distorting illusions: Muller-lyer illusion line of identical length appears longer
when it ends I na set of arrowheads pointing outward than inward. Ponzo illusion converging lines enclose 2 obj of identical size leading us to perceive the object closer to
the converging lines as larger. Horizontal-vertical illusion vertical line of a upside
down t to be larger. Ebbinghaus-titchener illusion illusion that a circle surrounded by
smaller circles is larger than a circle surrounded by larger circles.
Change blindness – poor at detecting obvious changes in complex scenes if those
changes occur during eye movements while lights are flickering or during frame changes
in a video series. Inattentional blindness – basketball and gorilla which demonstrates we
need to be paying very close attention to notice even dramatic changes in our
Synesthesia: condition in which people experience cross modal sensations like hearing
sounds when they see colours. May be an extreme version of the cross modal responses
that most of us experience from time to time. Grapheme colour synth- 6 seems red and
five seems green. Music colour synth, and lexical taste synth words have associated tastes
4.5 When we can‟t see or perceive visually
Blindness: vision less than 20/200. Blind cope with loss of vision by relying more on
other senses including touch. Visual cortex of blind persons undergoes profound changes
in function rendering it sensitive to touch inputs; they can devote more cortex to touch.
Colour blindness: loos of perception for one or more colours is most often due to the
absence of one or more cones from genetic abnormalities. Dichromats have two cones
and are only missing one, monochromaty is very rare.
Motion blindness: patients cant seamlessly string still images processed by their brains
into the perception of ongoing motion. Person cant see a cup fill, firs tits empty then 2
seconds later its overflowing.
Visual agnosia: deficit in perceiving objects, can tell us the shape an colour but cannot
recognize it. The damage lies in visual areas that piece together visual elements
Blindisght: remarkable phenomenon in whch people with cortical blindness resulting
from damage in V1 cant make correct guesses about things in their environment even
thorugh they cant see them.
Sound: mechanical vibration
Sound is vibration, mechanical energy travelling through a medium usually air. Sound
waves can travel through any medium except a vacuum since there are no particles to
Pitch: corresponds to the frequency of the wave, higher frequency higher pitch and vise
versa, pitch = cycles/s.
Loudness: Amplitude or height of the sound wave corresponds to loudness, measured in
decibles. Loud noise results in increased wave amplitude because there‟s more
mechanical disturbance, more vibrating particles.
Timbre: quality or complexity of the sound, different instruments differ in sound and
voices. 4.6 how the ear works
Structure: Outer middle and inner. Outer pinna and ear canal has the simplest
functions, funnels sound waves onto the tympanic membrane(eardrum). On the other side
of the eardrum lies the middle ear, containing the ossicles, three tiniest bones in the body,
named malleus, incus and stapes, which vibrate at the frequency of the sound wave
transmitting it from the tympanic membrane to the inner ear.
Cochlea and organ of corti: Cochlea lies in the inner ear and converts vibration into
neural activity, has spiral shape. Outer part of cochlea in bony but its inner cavity is filled
with a thick fluid. Vibrations from sound waves disturb this fluid and travel to the base of
the cochlea where pressure is released and transduction occurs.
Organ of corti and basilar membrane have hair cells embedded within them and is the
place where transduction of info takes place. Convert acoustic info into action potentials.
Hair cells contain cilia that protrude into the fluid of cochlea and when sound waves
travel through the cochlea the resulting pressure deflects these cilia exciting the hair cells
and that into feeds into the auditory nerve which travels to the brain.
4.7 Auditory perception
Pitch P: Different tones are perceived at different areas of the basilar membrane and thus
get transferred to different places in the primary auditory cortex. Hair cells at the base of
the basilar membrane respond to high pitched tones and at the top to low pitches tones
and this is called place theory.
Two routes for low pitched tones: frequency theory rate at which neurons fire action
potentials faithfully reproduces the pitch, works up to 100Hz. Volley theory is a variation
of frequency theory that works for tones between 100 and 5000Hz. Sets of neurons fire at
their highest rate slightly out of sync with each other to reach overall rates up too
Localization of sound: Auditory nerve enters the brain stem some of the axons connect
with cells on that side and the others cross over to the other side of the brain, however
they take different routs and arrive out of sync called binaural cues. Sound shadow, one
ear hears the direct source