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Sensation and Perception

Terms in this set (28)

Explain the concept of veridical relationships. Why is it not possible to know the true nature of the external world
the correspondence between objective reality and internal representation

our knowledge is based on our senses

different people perceive different things differently

the physical world is known through instrumentation

within species differences=individual differences
between species differences=ecological differences
Define perception, sensation, and transduction; which processes are we aware of?
perception- CONSCIOUS experience of objects and object relationships

sensation- UNCONSCIOUS process. first contact between the organism and the environment

Transduction- UNCONSCIOUS process. converting one type of energy into another
What is the concept of the umwelt and how does it pertain to the concept of veridicality?
Jakob von Uexkell
the environmental factors, collectively that are capable of affecting the behavior of an animal or individual
between species difference
relates to verdicality bc the environment can affect how we sense things which can give different percepts
Identify and explain the 4 theoretical approaches to the study of perception?
1. Classical Structuralism- perception is explained in terms of simple sensory experiences and the elaboration of these by more cognitive processes.
Equation: S1+S2=P

2. Direct Theory- all information is provided in the ambient optic array and affords "direct" perception WITHOUT cognitive or brain processing (J.J. Gibson's theory)
Equation: S=P

3. Gestalt Theory- the whole has priority over its parts and differed from the sum of its parts.
Equation: S1+S2 < P

4. Constructivism- information processing that involves selective attention and sequential integration of features in our world. Deals with how we put our perceptions of the world together out of the fragmentary glimpses we receive from eye movements. (Movie clip example)
Equation: S1+S2+M=P
How do Gestalt theories differ from the structuralists?
Structuralism adds together sensations (parts) to see the percept (whole). However, gestalt theory believes the separate parts are less important than the whole
What is the Phi Phenomenon and how did its discovery form the basis of Gestalt Psychology? What are the philosophical bases of Gestalt Psychology?
Phi Phenomenon is the optical illusion of perceiving continuous motion between separate objects viewed rapidly in succession.

Defined by Max Wertheimer in Gestalt Psychology

shows that the perception of each simple stimulus resulted in an emergent perception (motion) that was beyond and different than the sum of its parts


Gestalt Psychology comes from:
1. the holistic viewpoint
2. organisms do not merely respond passively to their environments; they have transactions with their environments
3. relationship between experience and actions is brain physiology and isomorphic
4. perception is governed by laws and principles of organization
Describe Gibson's Theory of Direct perception. name and describe 3 examples of invariant information that are fundamental to perception
direct theory- all information provided is in the ambient optic array

3 Invariant Information
1. texture gradient (brick sidewalk)
2. flow patterns (looking out window of moving car, speed is faster in foreground and slower in the distance)
3. Horizon Ratio- extent of object that extends above horizon is divided by extent of object that extends below the horizon (determined by height of observers eye)
Name and describe some of the laws of perception identified by Gestalt theorists
Proximity- when we see a number of similar objects we tend to perceive them as groups or sets of those that are close to each other

similarity- when similar and dissimilar objects are mingled, we see the familar ones as groups

continuation- tend to see lines that have coherent continuation or direction take precedence over lines that form a shape

pragnanz- tendency to see the simplest shape, rather than a complex one

size constancy- when an object of known size, when far off, projects a small mage on the retina, yet we sense the real size bc of relationships of the object with other perspective giving features
Describe the experiments of Weber and JNDs and how the results of his experiments were modified by Fechner to form the foundation of the science of psychophysic?
Weber's experiments with weight and musical pitches

define JND- weight increase necessary for subject to detect a difference

Fechner's Changes:
stimulus threshold as 0 point
assumed JNDs are equal in range of sense quality- sensation based scale
proposed a logarithmic relationship btwn subjective stimulus scale and stimulus intensity
What are the 4 tasks or problems for psychophysics? Identify, define and provide an example of each
Detection-detect the presence of energy changes in the environment
Ex: detecting a ticking sound at different distances

Identification- identifying the stimulus
Ex: identifying a noise as a ticking clock

Discrimination- differentiate between stimuli
Ex: deciding which weight in which hand is heavier

Scaling- provides numeric representation of object properties or events. different types of scaling
Ex: degrees Celsius
Describe an experiment that provides an example of absolute threshold, method of constant stimuli, and the method of limits. What are the respective disadvantages of the constant stimuli and method of limits? Also, describe the method of adaptive testing
threshold for hearing a fairly high pitch is chosen prior to testing (method of limits) also, a fixed number of the same pitches will be used each trial (method of constant stimuli) It is then determined when participants are first able to hear the pitch (absolute threshold)

disadvantages:
constant stimuli- threshold definition is arbitrary and potentially not subject to testing
method of limits- threshold could be misjudged and estimated wrong

adaptive testing- allows the threshold to be tracked over time. It begins with defending method of limits then increase and decrease as you hover around the threshold
What is signal detection theory? What are the experimental confounds that are overcome by its utilization? Describe an experiment that utilizes this approach and how the data are evaluated.
Signal Detection Theory- technique for obtaining an accurate sensory threshold estimate that incorporates observers response bias into the analysis

Uses catch trials or no stimulus trials

controls for motivational and cognitive factors that influence threshold estimates

Signal was present and person says yes=hit
Signal was present and person says no=mis
No Signal and person says no=correct rejection
No Signal and person says yes=false alarm
What is Magnitude Estimation and how does it differ from other approaches to scaling?
Magnitude Estimation- when observers are asked to assign numbers to stimuli on the basis of how intense they appear to be

stimuli are judged one at a time and no zero can be used

differs from scaling bc ME measures the proportion of intensity of the physical stimulus. ME can have scales differ from individuals
Define and give an example of nominal, interval, ordinal, and ratio scale
nominal scale- no quantitative significant
Ex: Trial 1, Trial 2, etc

Ordinal- ranks items on basis of some quantity
Ex: Top 10 US colleges

interval- in addition to rank, also provides magnitude or spacing between numbers
Ex: thermometer

ratio- used only when equality, rank order, equality of intervals and of ratios, a true zero point can be determined
Ex: physical measurements of mass, density or length
What is the difference between a prothetic and metathetic continuum? Which scales may be used in characterizing stimuli for these dimensions?
prothetic continuum- changes from one level of sensation to another come about by adding or subtracting from what is present
Ex: brightness, heaviness, loudness, or sweetness
ALL SCALES

metathetic continuum- when the change in stimulus is in quality not quantity
Ex: red and green
ONLY NOMINAL SCALE

touch is an example of both
What is reaction time? What is the difference between simple reaction time and choice reaction time? Why are reaction time studies historically important?
reaction time- time between the onset of stimulus and the beginning of an overt response

simple reaction time- simply pressing a button immdiately after detecting a stimulus

discrimination reaction time- when a subject only presses if certain target stimulus appears

choice discrimination time- when a subject presses left key for target a, and right key for target b

providided the first quantification of mental events!!!!
How does stimulus intensity affect the ROC curve in signal detection theory?
ROC curve displays the relation between proportions of hits and false alarms as the decision conditions change. When a signal is rare or hard to detect the observer says no a large proportion of trials. when the signal occurs frequently or is strong, the observer says yes on a larger proportion of trials
Describe the 2 general classes of stimuli and identify what the task is for perception? Why is context an important consideration in the perceptual process?
distal stimulus- an actual object or event in the physical world

proximal stimulus- information that our sensory receptors receive about an object

perception is multi-dimensional interaction between several sources of info including the proximal, distal, and contextual stimuli. Contextual cues relay information that shape our perceptions
Define and give 2 examples of the Gibsonian concept of affordances, why is it important to isolate "higher level" stimulus features?
affordance- set of actions that a specific object of environmental situation affords or makes available to the receiver

Ex: a particular wavelength of light "affords" a flower that bears nectar to a bee
a cleared path through the woods "affords" walking, a ravine prevents it by "affording" energy

easier to perceive an invariant unit than to perceive all variables separately
What is a perceptual constancy adn why is the function important to organisms? Also what are the 3 general classes that we can sort the many varieties of perceptual constancies into?
perceptual constancy- properties of objects that tend to remain constant in consciousness although our perception of the viewing conditions may change

world would be continually changing without PC

3 classes
1) object properties: size constancy/shape constancy
2) object qualities: color/whiteness constancy
3) locations of objects relative to the observer
REFER TO STUDY GUIDE
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What is Emmert's Law and what does it demonstrate?
states that quantitative relationship between apparent size and apparent distance; objects appear larger when projected on a more distal surface and smaller when projected on a more near surface

how size and distance perception interact by means of a size constancy mechanism
Contrast Direct and Constructive Theories of size constancy. Is one theory better?
direct theory:
all info for perception is found in the proximal stimulus. texture gradients and linear perspective serve as distance cues
problem with "optical explanation" of size constancy

constructive theory:
allows for info besides just proximal stimulus
past knowledge to judge size
problem with attentional breakdown of size constancy

direct theory does a better job of identifying "extraproxinimal" stimulus features that shape perception while constructive theory is useful for treating cognitive dimensions of perception
3 illusions
ponzo illusion
road and logs
size constancy mechanism

mueller-lyer illusion
house corners
implied depth cues

moon illusion
moon appears larger on horizon
trick with distnace cues
Difference in data-driven and conceptually driven object identification? examples
data driven- bottom uo processing
processing of stimulus info

conceptually driven- top down processing
driven by knowledge and experience
What is lightness constancy? ratio principle and illustrate it with example
lightness of a surface remain unchanged despite changes in physical illumination
REFER TO STUDY GUIDE
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DO NOT FORGET FIRST QUESTION!!!!!!!!!!!!
seriously
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