Introduction to Perception Flashcards
1
Q
What are the steps in the perceptual process?
A
- stimulus in the environment (distal stimuli)
- stimulus hits the receptors (proximal stimuli)
- receptor processes
- neural processing
5,6,7. perception, recognition, action
2
Q
What is the perceptual process?
A
- seven steps, plus knowledge inside the person’s brain, describe the process of perception
- these steps occur between the time a person looks at the stimulus in the environment, perceives the stimulus, recognizes it, and takes action toward it
3
Q
What is distal stimuli?
A
- environmental stimuli are all objects in the environment that are available to the observer
- observer selectively attends to objects
- stimulus impinges on receptors resulting in internal representation
- stimuli from the environment reach the sensory receptors
- information about object is carried by light
4
Q
What are proximal stimuli?
A
- the representation of the distal stimulus on the receptors
- stimulus is in proximity to the receptors
- light is transformed when it is reflected from object, when it travels through the atmosphere and when it is focused on the eye’s optical system
- image on retina
5
Q
What is transformation?
A
- When the stimuli and responses created by stimuli are transformed, or changed, between the environmental stimuli and perception
- first transformation occurs when light hits the object and is then reflected from the object to the person’s eyes
- as this reflected light enters the eye, it is transformed again as it is focused by the eye’s optical system onto the retina
6
Q
What is representation?
A
- everything a person perceives is based not on direct contact with stimuli but on representations of stimuli that are formed on the receptors and the resulting activity in the person’s nervous system
7
Q
What are receptor processes?
A
- Sensory receptors are cells specialized to respond to environmental energy
- each sensory system’s receptors specialized to respond to a specific type of energy
- Transduction occurs, which changes environmental energy to nerve impulses
- The end result is an electrical representation of the object
- when the sensory receptors receive the information from the environment: they transform environmental energy into electrical energy and they shape perception by the way they respond to different properties of the stimuli
8
Q
What is transduction?
A
- the transformation of environmental energy to electrical energy
- allowing the information that is out there to be transformed into a form that can be understood by the brain
- sensory receptors are like a bridge between the external sensory world and internal (neural) representation of that world
9
Q
What is neural processing?
A
- changes that occur as signals are transmitted through the maze of neurons
- sensory receptors travel through a vast interconnected network of neurons and transmit signals from the receptors to the brain and then within the brain and change or process these signals as they are transmitted
- some signals become reduced or are prevented from getting through and others are amplified so they can arrive at the brain with added strength
- the changes in these signals that occur as they are transmitted through this maze of neurons is neural processing
- the electrical signals created through transduction are sent to a sense’s primary receiving area (lobe)
- once signals reach the primary receiving areas, they are then transmitted to many other structures in the brain
10
Q
What is the cerebral cortex?
A
- 2 mm
- creating perceptions, language, memory, emotions, and thinking
11
Q
What are behavioural responses?
A
- perception, recognition and action
- electrical signals have been transformed into the conscious experience of perception which leads to recognition
- Person perceives object
- Person recognizes it
- Person reacts to it
12
Q
What is visual form agnosia?
A
- an inability to recognize objects
13
Q
What is knowledge?
A
- any information the perceiver brings to a situation
- prior experience or expectations
- can affect steps in the perceptual process
- ex: rat man demo
14
Q
What is bottom up processing?
A
- Processing based on incoming stimuli from the environment, reaching the receptors
- data-based processing
15
Q
What is top down processing?
A
- Processing based on the perceiver’s previous knowledge (cognitive factors)
- knowledge-based processing
- very involved in perception
- as stimuli become more complex, the role of top down processing increases
- our knowledge of how things usually appear in the environment, baed on our past experiences, can play an important role in determining what we perceive
16
Q
How can we split the perceptual process into three major components?
A
- stimulus (distal and proximal)
- physiology (receptors and neural processing)
- behaviour (perception, recognition, action)
16
Q
What is the stimulus-behaviour (perception) relationship?
A
- relates stimuli to behavioural responses
- study using psychophysics (measures relationship between physical and psychological)
- oblique test using grating acuity, (smallest width of line that can be detected - indicate correct orientation)
- the results show that acuity is best for gratings oriented vertically or horizontally
- the stimulus is oriented gratings, and the behavioural response is detecting the grating’s orientation
16
Q
What is the oblique effect?
A
- people see vertical or horizontal lines better than lines obliquely
17
Q
How can we study the perceptual process?
A
- by observing perceptual processes at different stages in the system
- the stimulus-behaviour (perception) relationship
- the stimulus-physiology relationship
- the physiology-behaviour (perception) relationship
18
Q
What is the stimulus-physiology relationship?
A
- relationship between stimuli and physiological responses
- studied by measuring brain activity
- horizontal and vertical orientations caused larger brain responses in visual brain areas than oblique orientations
19
Q
What is the physiology-behaviour (perception) relationship?
A
- relates physiological responses and behavioural responses
- Horizontal and vertical orientations result in better acuity (behavioural response) and more brain activation (physiological response) than oblique orientations
- When behavioural and physiological responses to stimuli are similar like this, researchers often infer the relationship between physiology and behaviour
- can measure the physiology–behaviour relationship directly
- measuring both the brain response and behavioural sensitivity in the same participants
- more sensitive to the horizontal and vertical orientations
- fMRI
- measurements showed larger brain responses to vertical and horizontal gratings than to oblique gratings
20
Q
What is optical imaging?
A
- Electrical activity of neurons is related to local metabolic activity and blood flow
- Correlates of brain activity:
- Blood volume changes
- Blood oxygenation changes
- Light scattering changes caused by ion
and water movementH
21
Q
How can we measure perception?
A
- absolute threshold
- difference threshold
22
Q
What is the absolute threshold?
A
- the smallest stimulus level that can just be detected
- the smallest amount of energy needed to detect a stimulus
- thresholds measure the limits of sensory systems; they are measures of minimums—the smallest
23
What are methods for measuring the threshold (classical psychophysical methods)?
- method of limits
- method of constant stimuli
- method of adjustment
24
What is the method of limits?
- stimuli of different intensities presented in ascending or descending order
- observer responds to whether she perceived the stimulus '
- cross over point (change from yes to no or vice versa) is the threshold
- The threshold is then determined by calculating the average of all of the crossover point
25
What is the method of constant stimuli?
- the stimulus intensities are presented in random order
- the threshold is usually defined as the intensity that results in detection on 50 percent of trials
- most accurate method
- but it is time consuming
26
What is the method of adjustment?
- the participant—rather than the experimenter—adjusts the stimulus intensity continuously until he or she can just barely detect the stimulus
- This just barely audible intensity is taken as the threshold
- the threshold is determined by taking the average setting
- fastest
27
What is the difference threshold?
- measure the threshold between two stimuli
- the smallest difference between two stimuli that enables us to tell the difference between them
28
What is the technique used to answer the question: What Is the Perceptual Magnitude of a Stimulus?
Magnitude Estimation
29
What is magnitude estimation?
- The experimenter first presents a “standard” stimulus to the participant and assigns it a value of, say, 10
- participant then hears sounds of different intensities
- assign a number to each of these sounds that is proportional to the loudness of the original sound
- participant assigns a loudness value to each sound intensity
- This number for “loudness” is the perceived magnitude of the stimulus
30
What is the technique used to answer the question: What Is the Identity of the Stimulus?
Recognition Testing
31
What is the recognition test?
- testing the ability of people with brain damage
- asking them to name objects or pictures of objects
- Recognition is also used to assess the perceptual abilities of people without brain damage
32
What is the technique used to answer the question: How Quickly Can I React to It?
Reaction Time
33
What is reaction time?
- The speed with which we react to something can be determined by measuring reaction time
- the time between presentation of a stimulus and the person’s reaction to it
- participant responded more quickly when the target was flashed where he or she was directing attention
33
What is the technique used to answer the question: How Can I Describe What Is Out There?
Phenomenological Report
34
What is a phenomenological report?
- Describing what is out there
- Phenomenological reports are important because they define the perceptual phenomena we want to explain, and once a phenomenon is identified, we can then study it using other methods
35
What is the technique used to answer the question: How Can I Interact With It?
Physical Tasks and Judgments
36
What are physical tasks and judgements?
- This last question is concerned not with perception but with actions that follow perception
37
Why is the difference between physical and perceptual important?
- One of the most crucial distinctions in the study of perception is the distinction between physical and perceptual
- Perception of the light is measured not by determining the intensity but by determining perceived brightness using a method such as magnitude estimation
- there is not a one-to-one relationship between the physical intensity of the light and our perceptual response to the light
- what physical measuring instruments record and what we perceive are two different things
38
What is the electromagnetic spectrum?
- a band of energy ranging from gamma rays at the short-wave end of the spectrum o AM radio and AC circuits at the long-wave end
- we see just the small band of energy called visible light, sandwiched be- tween the ultraviolet and infrared energy bands
