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PSYB51H3 Study Guide - Midterm Guide: Electric Shock, Amacrine Cell, Retinal Pigment Epithelium

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Matthias Niemeier
Study Guide

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Perception + reality are products of evolution
- Survival/importance of type of energy in the environment determines
which senses have developed/may not see entire reality but we see
what is important to our survival
- Reality/perception is dependant on info gathered by our senses
- understanding of reality is restricted to things we can perceive
- forgot aspect of learning (added by Heraclitus)
- truest sense of reality comes from people’s minds and souls (not
from body)
- Nativism= idea that mind produces ideas that are not derived from
external source knowledge is born with you
- Dualist view of the world both mind and body exist
- mind-body dualism= the idea positing the existence of 2 distinct
principles of being in the universe: spirit/soul and matter/body
- Can never step into the same river twice “panta rhei”= everything
- Idea that perceiver cannot perceive the same thing twice in exactly the
same manner experience/learning adaptation alters perception
change (we pick out things at change and adapt to things that are
- World is made up of colliding atoms sensations caused by atoms
leaving object and interacting with our sense organs perception=
result of physical interaction between world and our bodies
- *true until today sensory transducers= physical energy to neural
energy (hair in cochlea, taste-buds, retina in eyes)
- Believed that everything that could ever be known/imagined had to
be learned through our senses
- Sought to explain how all thoughts, even complex ones, could be
constructed from experience with a collection of sensations
- Invented PSYCHOPHYSICS and theory of PANPSYCHISM, thought to be
the true founder of experimental psychology
- Followed up Weber’s work on Weber’s laws/fractions
Adaptation: (Heraclitus) a reduction in response caused by prior or
continuing stimulation
- Ex. Looking at male/female faces and a hybrid, you perceive the
hybrid as the opposite of what you were primed with because you
- Ex. Primed with rat, you see a rat/ primed with man, you see a man
due to learning

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Monism (opposite of dualism/Descartes)= mind and matter are formed
from/reduced to a single ultimate substance or principal of being just mind
or just matter
- Materialism= type of monism=physical matter is the only reality and
everything including the mind can be explained in terms of matter and
physical phenomena
Empiricism (opposite of Nativism/Plato)= the idea that experience form the
senses is the only source of knowledge not born with knowledge, learn
from your senses
Reality= in btwn Nativism (Plato) and Empiricism born with and gradually
learn knowledge
Panpsychism (Fechner)= idea that all matter has consciousness
Psychophysics (Fechner)= science of defining quantitative relationships
btwn physical and psychological (subjective) events
Weber’s Law= smallest CHANGE in a stimulus, such as weight of an object,
that can be detected is a constant proportion of the stimulus level
- (delta)I= kI
- delta I= JND/difference threshold, k= Weber fraction, I=stimulus level
- JND= smallest detectable difference btwn 2 stimuli, minimum change
in stimuli that can be correctly judged from the reference stimuli
two-point threshold: minimum distance at which 2 stimuli can be
distinguished (different depending on size of somatosensory cortex,
Ex. Finger/shoulder)
Fechner’s Law: principle describing the relationship btwn stimulus
magnitude and resulting sensation magnitude such that the magnitude of
subjective sensation increases proportionally to the logarithm of the stimulus
intensity (S increases less quickly than R)
- S= k log R
- S= psychological sensation, k=constant, R=physical stimulus level
Stevens’ Law: principle describing the relationship between stimlus
magnitude and resulting sensation magnitude such that magnitude of
subjective sensation is proportional to stimulus magnitude raised to an
- Expansion of Fechner’s law as there were some exceptions (Ex.
Electric shock)
- S=aI^b
- S=sensation, I= stimulus intensity, b=exponent, a= constant
- Used magnitude estimation to formulate graph
- Exponent of 1 sensation and stimulus intensity rise proportionally,
exponent of <1 S rises slower than I,
exponent of >1S increases faster than I (exception to Fechner’s Law)
Absolute threshold= minimum amount of stimulation necessary for a
person to detect a stimulus 50% of the time (Ex. Absolute threshold for
emotional experience when do u first detect a smile? Whereas JND would
be how different do 2 faces have to be in order to notice the difference)
1. Method of constant stimuli (Fechner)

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- Many stimuli from rarely to almost always perceivable (or rarely to
almost always perceivably different) are presented one at a time.
Responses= y/n or same/different. Stimulus levels and responses are
graphed and the intensity of the stimulus where it was perceived 50%
of the time= absolute threshold.
2. Method of limits (Fechner)
- Particular dimension of a stimulus/ difference between two stimuli is
varied incrementally until the participant responds differently
repeated trials, absolute threshold is line where 50% of the time was
responded yes/no
3. Method of adjustment (Fechner)
- Method of limits in which subject controls change in stimulus
- *decreasing accuracy from 1-3 but increasing efficiency
4. Magnitude estimation
- Participants are asked to assign values according to perceived
magnitudes of stimuli (better if participant decides scale as well)
5. Cross-modality matching
- Similar to magnitude estimation= matching intensities/magnitudes of
sensations that come from different modalities
Signal Detection Theory: A psychophysical theory (not method) that
quantifies the response of an observer to the presentation of a signal in the
presence of noise
- Calculate d’ (measures of sensitivity) based on hit/false alarm rates
- Interprets the importance of internal noise vs. external noise
- Influenced by biases (costs of decisions, probability of events,
- For a fixed d’= all you can do is change your pattern of errors by
shifting the response criterion (shift to left= no misses, but increased
# of false alarms and vice versa) changing response criterion of a
fixed d’= changes hits/false alarms in predictable way
Receiver Operating Characteristic (ROC) curve= in studies of signal detection,
the graphical plot of the hit rate as a function of the false alarm rate hits= y
axis, false alarm=x axis if hit/false alarm rate is the same= diagonal which
means observer can’t tell difference btwn presence and absence of stimuli
as the observer sensitivity increases, the curve bows upwards towards the
upper left corner (d’ increases).
- Upper left corner= perfect ability to distinguish signal from noise
Fourier Analysis= analyses that allow understanding about how complex
sounds (music/speech), motions, images etc. can be decomposed into a set of
simpler signals
- Images= broken down into components (spatial frequencies) that
capture how often changes from light to dark occur over a particular
region in space
- spatial frequency= # of cycles of a grating per unit of visual space
(usually specified in cycles per degree= # of pairs of light/dark bars
per degree (size of a thumbnail at arms length) of visual angle
- find that many individual neurons have strong preferences for
frequency components
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