Flashcards in chapter 3 Sensation & Perception Deck (68):
What is Psychophysics?
the relating of mental experiences with physical reality; a specialized sub-domain of research on sensation & perception
What are the two issues of interest in psychophysics?
1) Detection of sensory experience: telling us what info a person can sense outside of themselves
2)Discrimination of sensory experiences: how much the world needs to change before a person registers the difference
What is the minimal amount of energy needed to detect a stimulus called?
Sensory threshold, if detectable
more than 50% = supraliminal
less than 50% = subliminal
What is the smallest amount of physical change a person can detect called?
the JND, just noticeable difference
Webers Law of JND?
earliest attempt to capture the JND. k = change in I/ I.
-more simply stated, the size of the just noticeable difference (i.e., delta I) is a constant proportion of the original stimulus value.
-For example: Suppose that you presented two spots of light each with an intensity of 100 units to an observer. Then you asked the observer to increase the intensity of one of the spots until it was just noticeably brighter than the other. If the brightness needed to yield the just noticeable difference was 110 then the observer's difference threshold would be 10 units (i.e., delta I =110 - 100 = 10). The Weber fraction equivalent for this difference threshold would be 0.1 (delta I/I = 10/100 = 0.1)
Fechner' Law of JND
Fechner's law states that the subjective sensation is proportional to the logarithm of the stimulus intensity. ... For example, if a stimulus is tripled in strength (i.e., 3 x 1), the corresponding perception may be two times as strong as its original value (i.e., 1 + 1).
-denoted. S = k log R".
Stevens Power Law of JND's
The general form of the law is
-ψ(I) =k I^a
where I is the magnitude of the physical stimulus, ψ(I) is the subjective magnitude of the sensation evoked by the stimulus, a is an exponent that depends on the type of stimulation, and k is a proportionality constant that depends on the units used.
When we judge differences between symbols more rapidly when they differ considerably on some symbolic dimension such a value, this is called--
The Symbolic Distance Effect
Semantic Congruity Effect
the condition in which a person's decision is faster when the dimension on being judged matches or is congruent with the implied dimension
the layer of the eye covered w/ the rods & cones that initiate the process of visual sensation & perception
the reception of physical stimulation & encoding of it into the neutrons system
Explain the process by which light enters eye and is converted into sensory images
Light waves enter the eye, the light is then focused by lens & inverted, then projected onto the retina. The retina has 3 layers of neutrons: 1)rods & cones 2) bipolar cells and 3)ganglion cells.
Rods & Cones
are neutrons stimulated by light, beginning the process of vision. Patterns of neural firing from these cells pass on to a second layer- the bipolar cells.
-Rods don't help with color vision, which is why at night, we see everything in a gray scale. The human eye has over 100 million rod cells.
-Cones require a lot more light and they are used to see color
these cells collect the messages from the rods and cones & move them along to a third layer- the ganglion cells
these cell's axons coverage at the rear of the eye, forming bundles of fibres that make up the optic nerve. They receive the messages from the bipolar cells.
binocular pathway of info flow from eyes into the visual cortex, and the left hemisphere processes the images that come from the right side and vice versa.
the process if interpreting & understanding sensory information; that act of sensing then interpreting information
How do Saccades and Fixations work?
the eyes jerk & sweep from one point to another in fast movements-saccades-taking anywhere from 25ms-175ms, plus taking about 200ms just to plan these movements. When your eyes are focused on a singular point these are called the fixations, that happen in between the saccades.
our failure to notice changes in visual stimuli when those changes occur during a saccade
we sometimes fail to see an object we are directly looking at because our attention is directed elsewhere
a condition in which a person will have inappropriate & involuntary sensory experiences in addition to typical sensory experience
-Projectors: those whose extra sensory experiences appear to them as 'out in the world'
-Associators: theirs are in their mind
Why?: 1) perhaps a lower ability to suppress inappropriate feedback loops in perceptual processing
2) perhaps because there is an incomplete pruning of extra cortical connections during development
most common form of synethsesia where one experiences colour when reading words or letters
Visual Sensory Memory
the short duration memory system specialized for holding visual information, lasting no more than about 250ms to 500ms
the perceptual phenomena in which a visual stimulus still seems to be present even after its termination, usually a few hundred ms to a few seconds.
Span of Apprehension/Attention
the number of items recallable after any short duration- span of 'immediate memory.'
Whole report condition vs Partial Report condition (Sterlings experiment)
WRC: when the participants are asked to recall as many letters as the can from the total 12 shown (avg =4.5)
PRC: when the participants are asked to recall only a select row of letters (success was 76% meaning visual memory for entire display is also 76%, we just can't recall it all)
what we call the contents of the iconic memory, the visual image that resides in iconic memory
simple loss of information across time, presumably caused by a fading process, especially in sensory memory
Interference, famous example/experiment?
an explanation for 'forgetting' of some target information in which related or recent information competes with or causes the loss of target info
-example: Averbach and Coriell's experiment where following a presented stimulus either a bar or circle were flashed after. The circle interfered with memory recall creating erasure/masking
Neisder's term for mental attention directed towards, for example, the contents of visual sensory memory & therefore responsible for transferring that info into short term memory.
the memory system that is used across a series of eye movements to build up a complete & stable understanding of the visual world
a German term adopted into psychological terminology referring to an entire pattern, form, or configuration. The term always carries the connotation that decomposing a pattern into its components in some way loses the essential wholeness of the cohesive pattern
a gestalt grouping principle, when viewing an image, part of the image is treated as the figure or foreground (object identified) and that is separated from the background.
(think vases or faces example)
a gestalt grouping principle that is used by visual perception to close up gaps in a percept tp help identify a whole object
(think square with little gaps in the lines)
a gestalt grouping principle where we group objects that are near to one another- if they are near they become grouped
gestalt grouping principle, in which elements that are usually similar in some way, tend to be grouped together
assumes that when an edge is interrupted, people assume that it continues along in a regular fashion
entities that move together are grouped together
theory that we have stored models of all categorizable patterns
(simple and flawed understanding)(fonts vary a lot, but we recognize letters in different ones)
theoretical approach in which stimuli (patterns0 are identified by breaking them up into their constituent features
Selfridges 'demon' model where 'demons' along a line are each responsible for their own roles; encoding patterns, matching simple features, matching whole patterns, & finally the decision making 'demons' deciding what is seen- they all act at the same time.
What are 3 Important ideas in Selfridges model for pattern recognition?
1) Feature Detection
2) Parallel Processing
3) Problem Solving
What is feature detection (Selfridges model)
when the 'demons' detect & report elementary, simple features. (Hubel & Wiesel's work demonstrated a neurological basis for this function)
What is Parallel Processing (Selfridges model)
the computational demons all work at the same time, each one trying to match its own feature while the others are doing the same thing
What is problem solving (Selfridges model)
Perception is a problem solving process- the visual system must put the bits & features together.
What ingredient was missing in Selfridges model??
Context! and people's expectations! these affect how we perceive the world
conceptually driven processing
the tendency NOT to perceive a pattern, whether a word, picture, or visual stimulus, when it's quickly repeated
a tendency to read another word that should be in the sentence, based on context.
computational approach often used in cog science.
Parallel distributed processing principles overview
complex mental operations are the combined effects of the massively parallel processing that characterizes a network
What are the PDPP (parallel distributed processing principles) composed of?
1) input level- consists of input units
2) Hidden level- composed of hidden units that match features in the stimulus
3) Output units- categorize the matched features in a simple 3 lvl connectionist model
Biederman's (RBC) Recognition by Components Theory
(explain and what are drawbacks?)
we recognize objects by breaking them down into their parts, & then look up this combination in memory to see which object it matches
1) tied to bottom-up processing, where object recognition is strongly influenced by prior knowledge
2)retrieval of objects identity occurs almost as fast as identifying there even is an object
3) neurological evidence shows object recognition is a joint effort b/w 2 mental process & 2 different regions of brain - one for features & components- another for overall shape and form
how people use their knowledge of what an object is & how they would interact with it, to help identify it
failure or deficit in recognizing faces
disruption of face recognition
a disruption in perceiving pattens. damage in right hemisphere
a disruption in constructing mental percepts. Cannot perceive associate patterns.
3 things we learn from agnosia?
1) detecting features in a visual stimulus is separate & lateral process from sensation
2) detecting visual features is critical in constructing a perceived pattern
3)There is a separate step for hooking up the pattern w/ its meaning & name in memory
Explain the physical process of hearing
-Sound waves funnel into ear, causing
-tymponic membrane (ear drum) vibrates, causing,
-bones of middle ear move setting in motion
-fluid of inner ear cavity moves tiny hair cells along basilar membrane, generating
-the neural message is sent along the auditory nerve into the cerebral cortex
sense of hearing
Modality Effect, and 2 ideas it supports
superior recall of the end of the list when heard instead of seen.
1) the existence of auditory sensory memory
2) the persistence of auditory traces across a short interval of time
inferior recall of the end of a list in the presence of additional meaningful noblest auditory stimulus
Three types of cones and their wavelengths
Red- long wavelengths
Green- medium wavelengths
Blue- Short wavelengths
-trichromatic theory of colour: these three colour cones work in opposition to create the entire spectrum of colour we can see. (opponent process theory)
What is anomalous? name colour deficiencies
when one cone isn't working efficiently
if red: protoanomaly
if green: deutranomaly
if blue: Tritanomaly
What is Dichromacy? name colour deficiencies
when one cone isnt working at all
if red: protanopia
if green: deuteranopia
if blue: tritanopia
What is Rod Monochromacy?
when two cones don't work at all. You end up heavily relying on rods for vision