Psychology Midterm 2 Review
Chapter 5: Sensation and Perception
Synesthesia, which means quite literally “mixing of the senses”.
Synesthetes may experience sounds as colours or tastes as touch sensations that have different shapes.
Women are more likely to be synesthetes than men.
Sensation Process: Sensation 1) Stimulus is received by sensory neurons 2) Receptors translate
stimulus properties into nerve impulses (transduction) 3) Feature detectors analyze stimulus features
4) Stimulus features are reconstructed into neural representation 5) Neural representation is compared
with previously stored information in brain 6) Matching process results in recognition and
interpretation of stimuli. Perception
The binding problem: How do we bind all our perceptions into one complete whole while keeping its
sensory elements separate?
People with synesthesia may create additional perceptions of that rose that are inconsistent with its
Sensation is the stimulus-detection process by which our sense organs respond to and translate
environmental stimuli into nerve impulses that are sent to the brain.
Perception - making “sense” of what our senses tell us- is the active process of organizing this
stimulus input an giving it meaning.
Transduction is the process whereby the characteristics of a stimulus are converted into nerve
Decision Criterion, a standard of how certain they must be that a stimulus is present before they will
say they detect it.
Sensation refers to the activities by which our sense organs receive and transmit information, whereas
perception involves the brain's processing and interpretation of the information.
Psychophysics is the scientific study of how the physical properties of stimuli are related to sensory
experiences. Sensory sensitivity is concerned in part with the limits of stimulus detectability (asolute
threshold) and the ability to discriminate between stimuli (difference threshold).
The absolute threshold is the intensity at which a stimulus is detected 50 percent of the time.
Signal Detection Theory is concerned with factors that influence decisions about whether or not a
stimulus is present.
Subliminal Stimuli, which are not consciously perceived, can influence perceptions and behaviour in
subtle ways, but bot strongly enough to justify concerns about the subconscious control of behaviour
through subliminal messages.
The Difference Threshold, or just noticeable difference, is the amount by which two stimuli must
differ for them to be perceived as different 50 percent of the time.
Weber's law: the jnd is proportional to the intensity of the genreal stimulus and is constant within a
given sense modality.
Sensory Systems are particularly responsive to changes in stimulation, and adaptation occurs in
response to unchanging stimuli.
Our vision, measured in nanometers, extends from 700 to 400 nanometers.
Light waves enter through the cornea. Behind the cornea is the pupil, an adjustable opening that can
dilate or constrict to control the amount of light. Pupil's movements are controlled by the iris. Behind
the pupil is the lens (thinner on far objects, thicker on near objects). The retina is a multi-layered tissue at the rear of the eyeball.
The retina contains specialized sensory neurons and is an extension of the brain.
The retina contains two types of light-sensitive receptor cells called rods and cones.
There are 120 million rods and 6 million cones in the human eye.
Rods are primarily black and white brightness receptors, and are about 500 times more sensitive to
light than cones, however they do not give rise to colour sensations.
Cones, which are colour receptors, function best in bright illumination.
Rods and cones are fond throughout the eye except in the fovea, which contains only cones.
Bipolar cells have synaptic connections with the rods and cones. These cells then synapse with a layer
of about one million ganglion cells whose axons are collected in into a bundle to form the optic nerve.
Visual acuity, or ability to see fine detail, is greatest when the visual image projects directly onto the
Rods and cones translate light waves into nerve impulses through the action of protein molecules called
Dark Adaptation is the progressive improvement in brightness sensitivity that occurs over time under
conditions of low illumination. (during which the photopigment molecules are regenerated and the
receptor's sensitivity increases greatly.
Trichromatic Theory: there are three types of colour receptors in the retina.
Opponent-Process Theory: proposed that each of the three cone types responds to two different
wavelengths. (the canadian flag image)
Dual Process theory combines the trichromatic and opponent-process theories to account for the
colour transduction process.
Trichromats: people with normal vision. Dichromats: have a deficiency in one of the systems.
Monochromats: see only black and white (entirely colour blind).
From the retina, the optic nerve sends nerve impulses to a visual relay station in the thalamus, the
brain's sensory switchboard. From there, the input is routed to various parts of the cortex, particularly
the primary visual cortex in the occipital lobe at the rear of the brain. Some of these cells are called
feature detectors, which subdivide a visual scene into its component dimensions and process them
simultaneously (parallel processing).
The information, analyzed and recombined by the primary visual cortex, is routed to other cortical
regions known as the visual association cortex.
Sound is actually pressure waves in air, water, or some other conducting medium.
Sound waves, the stimuli for audition, have two characteristics: frequency, measured in terms of cycles
per second or hertz (humans can detect 20 to 20,000 hertz), and amplitude (the vertical size of the
sound waves) , measured in terms of decibels (db,a measure pf the physical pressures that occur at the
Frequency is related to pitch, amplitude is related to loudness.
Vibrating of these bones – the hammer (malleus), anvil (incus), and stirrup (stapes) – amplifies the
sound wavs more than 30 times.
The receptors for hearing are hair cells (16,000 of them) in the organ of Corti at the inner ear
Loudness is coded in terms of the number and types of auditory nerve fibres that fire. Pitch is coded in
two ways: 1) The Frequency Theory: Low frequency tones are coded in terms of corresponding
numbers of nerve impulses in individual receptors or by volleys of impulses from a number of
receptors. 2) The Place Theory: Frequencies above 4000 hertz are coded according to the region of the
basilar membrane that is displaced most by the fluid wave in the cochlear canal. Two ears play a crucial role in sound localization.
In Canada alone, almost 3 million people suffer from some form of hearing loss.
Conduction Deafness: caused by problems involving the mechanical system that transmits sound
waves into the cochlea. (i.e.Apunctured eardrum)
Nerve Deafness: caused by damaged receptors within the inner ear or damage to the auditory nerve
itself, and it cannot be helped by a hearing aid. ( i.e. Exposure to loud sounds).
Gustation (taste) and olfaction (smell) are chemical senses because their receptors are sensitive to
chemical molecules rather than to some form of energy. These senses are so intertwined that some
scientists refer to a common chemical sense.
Gustation: our sense of taste responds to only 4 qualities: sweet, sour, salty, and bitter.
Taste Buds are chemical receptors concentrated along the edges and back surface of the tongue.
Humans have 9,000 taste buds. Each taste bud is responsive to only 2 of the 4 qualities.
The receptors for smell are long cells that project through the lining of the upper part of the nasal cavity
and into the mucous membrane.
Humans have 40 million olfactory receptors.
The receptors that fire send their input to the olfactory bulb, a forebrain structure immediately above
the nasal cavity.
Pheromones: chemical signals found in natural body scents.
Humans are sensitive to at least 4 tactile sensations: pressure (touch), pain, warmth, and cold.
Our skin weighs between 2.7 and 4.5 kilograms, and is the largest organ in the body.
Primary receptors for pain and temperature are free nerve endings, simple nerve cells beneath the skin's
surface that resemble the bare branches of a tree in winter.
Free nerve endings in the skin and internal organs respond to intense mechanical, thermal, or chemical
stimulation and then send nerve impulses into the spinal cord, where sensory tracts carry pain
information to the brain. Once in the brain, the sensory information is relayed by the thalamus to the
somatosensory and frontal areas of the cerebral cortex.
Gate Control Theory: proposes that the experience of pain results from the opening and closing of
gating mechanisms in the nervous system.
Glial cells are involved in the creation and maintenance of pathological pain.
The nervous system has built in analgesics (painkillers) with opiatelike properties. They are called
“endorphins” which inhibit the release of neurotransmitters involved in the synaptic transmission of
pain impulses from the spinal cord to the brain.
Kinesthesis: provides us with feedback about our muscles' and joints' positions and movements. The
receptors are nerve endings in the muscles, tendons, and joints.
Vestibular Sense: the sense of body orientation or equilibrium, located in the vestibular apparatus.
Sensory Prosthetic Devices: provide sensory input that can substitute for what cannot be supplied by a
person's sensory receptors.
Perception involves both bottom-up processing, in which individual stimulus fragments are combined
into a perception, and top-down processing, in which existing knowledge and perceptual schemas are
applied to interpret stimuli.
Inattentional Blindness refers to the failure of unattended stimuli to register in consciousness.
Attention is an active process in which we focus on certain stimuli while blocking out other stimuli.
We cannot attend completely to more than one thing at a time, but we are capable of rapid attentional
Attentional processes are affected by the nature of the stimulus and by personal factors such as motives
The perceptual system is especially vigilant to stimuli that denote threat or danger. The Gestalt psychologists identified numerous principles of perceptual organization, including figure-
ground relations (We tend to organize stimuli into a central or foreground figure and a background)
and the 4 Gestalt laws: 1) The law of similarity: when parts of a configuration are perceived as
similar, they will be perceived as belonging together, 2) The law of Proximity: elements that are near
one another are likely to be perceived as part of the same configuration, 3) The law of Closure: people
tend to close the open edges of a figure or fill in gaps in an incomplete figure, 4) The law of
Continuity: people link individual elements together so that they can form a continuous line or pattern
that makes sense.
Perceptual schema: a mental representation or image.
Perceptual sets involve a readiness to perceive stimuli in certain ways, based on our expectations,
assumptions, motivations, and current emotional state (eg. The boat shooting down the plane).
Perceptual Constancies allow us to recognize familiar stimuli under changing conditions. There are 3
constancies in the visual realm: 1) Shape Constancy allows us to recognize people and other objects
from many different angles, 2) Brightness Constancy, the relative brightness of objects remains the
same under different conditions of illumination, 3) Size Constancy is the perception that the size of
objects remains relatively constant even though images on our retina change in size with variations in
Monocular cues to judge distance include linear perspective (the perception that parallel lines
converge or angle toward each other as they get farther away), Interposition (objects in front of us cut
off part of our view of more distant objects), Light and Shadow, Height in the Horizontal Plane,
Texture, Clarity, Relative size, and motion parallax (if we are moving, nearby objects appear to
move faster in the opposite direction).
Binocular Disparity occurs as slightly different images are viewed by each eye and acted upon by
feature detectors for depth. Convergence of the eyes provides a second binocular view.
The basis for perception of movement is absolute movement of a stimulus across the retina or relative
movement of an object in relation to its background.
Stroboscopic Movement is illusory.
Illusions are erroneous/incorrect perceptual hypotheses and perceptions. Perceptual constancies help
to produce a variety of context-produced illusions.
Our perceptions of tastes, odours, and textures are strongly influenced by our cultural experiences.
Some of our perceptual abilities are partially present at birth, but experience plays an important role in
their normal development.
Chapter 6: States of Consciousness
State of Consciousness: a pattern of subjective experience, a way of experiencing internal and external
Altered State of Consciousness: variations from our normal waking state.
Consciousness: our moment-to-moment awareness of ourselves and our environment. Consciousness
is: 1) Subjective and Private, 2) Dynamic (ever-changing), 3) Self-Reflective and Central to our
sense of self.
Consciousness is intimately connected to with the process of selective attention.
The most common measure of consciousness is self-report, however it is not always reliable.
Physiological measures (which are objective) establish the relationship between bodily states and
The human mind has 3 levels of awareness: The conscious mind, Preconscious mental events which
are outside current awareness but can be recalled under certain conditions, and Unconscious events
which cannot be brought into conscious awareness under ordinary circumstances. Freud suggested that nonconscious processes influence behaviour.
Controlled (effortful) processing: the voluntary use of attention and conscious effort.
Automatic Processing: can be performed with little or no conscious effort (however can reduce our
chances of finding new ways to approach problems).
DividedAttention: the ability to perform more than one activity at the same time.
Emotional and motivational processes also operate unconsciously and influence behaviour.
The mind consists of separate but interacting information-processing modules.
Circadian rhythms are 24 hour biological cycles that help to regulate many bodily processes.
The Suprachiasmatic Nuclei (SCN) are the brain's master circadian clock. Environmental factors,
such as the day-night cycle, help to reset our daily clocks to a 24 hour schedule.
SCN neurons link to the tiny pineal gland, which secretes melatonin, a hormone that has a relaxing
effect on the body. SCN neurons become active during the day and decrease the amount of melatonin
secretion, raising awareness.
Circadian Rhythms influence whether we are a “morning person” or a “night person”.
SeasonalAffective Disorder (SAD) is a cyclic tendency to become psychologically depressed during
certain months of the year.
Jet lag and Night Shiftwork also involve environmental disruptions of circadian rhythms (treated by
sunlight, melatonin, and activities).
Sleep and Dreaming:
We show patterns of beta waves when we are awake, and alpha waves when we close our eyes and
We cycle through different stages in our sleep every 90 minutes.
EEG measurements of brain activity indicate five main stages of sleep: Stages 1 and 2 are lighter sleep
(theta waves in stage 1 and sleep spindles in stage 2) , stages 3 and 4 are deeper, slow-wave (delta
waves) sleep. High physiological arousal (heart rate increases) and periods of rapid eye movements
(REM) characterize the 5 stage, REM or “paradoxical” sleep.
Several brain regions, including the brain stem, regulate sleep.
Newborns typically sleep 16 hours per day, half of which is REM.
15-24 year olds sleep on average 8.5 hours a day, elderly people sleep roughly 6.
Sleep Deprivation negatively affects mood, mental performance, and physical performance.
The Restoration Model proposes that we sleep to recover from accumulated physical and mental
Evolutionary/Circadian models state that species evolved unique waking-sleeping cycles that
maximized their chances of survival.
Insomnia is the most common sleep disorder.
Sleepwalking and night terrors typically occur during slow-wave sleep, where as nightmares occur
during REM sleep.
Dreams are most common in REM sleep. There are gender differences in dream content. Our cultural
background, current concerns, and recent events influence what we dream about.
Freud proposed that dreams fulfill unconscious wishes that show up in disguised form within our
Activation-Synthesis Theory regards dreaming as the brain's attempt to fit a story to random neural
Cognitive-Process Theories emphasize that dreaming and waking thought are produced by the same
mental systems. Drugs:
Drugs enter the bloodstream and are carried throughout the brain by small blood vessels, called
The blood brain barrier screens out many foreign substances, but some, including a variety of drugs,
manage to pass through.
First, neurotransmitters are synthesized inside the presynaptic (sending) neuron and stored in vesicles.
Next, neurotransmitters are released into the synapse, where they bind with and stimulate receptor sites
on the postsynaptic (receiving) neuron.
Finally, neurotransmitter molecules are deactivated by enzymes or reuptake. Psychoactive drugs act by
influencing one or more of these steps in a synaptic transmission.
Drugs alter consciousness by modifying neurotransmitter activity. Agonists increase such activity,
whereas antagonists decrease it.
Tolerance develops when the body produces compensatory responses to counteract a drug's effects.
Withdrawal occurs when drug use is stopped but such compensatory responses continue.
Substance Dependence represents a maladaptive pattern of substance use that causes a person
significant distress or substantially impairs that person's life. It can occur with or without physiological
Depressants decrease neural activity. The subjective “high” and liveliness associated with alcohol
depresses the activity of inhibitory brain centres.
Stimulants increase arousal and boost mood by enhancing dopamine and norepinephrine activity.
Opiates increase endorphin activity, producing pain r