GRE PSYCH (Perception)
Terms
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- perception
- how we organize or experience what our sensory systems pick up
- nativist theory
- perception and cognition are largely innate
- structuralist theory
- asserts that perception is the sum total of sensory input. The world is understood through bottom-up processing
- gestalt psychology
- revolves around perception and asserts that people tend to see the world as comprised of organized wholes. The world is understood through top-down processing
- current thinking on perception
- partially innate/sensory and partially learned/conceptual
- perceptual development
- increasing ability of a child to make finer discriminations among stimuli.
- James Gibson
- describes perceptual development
- optic array
- all the things a person sees. In perceptual development, trains people to perceive
- visual field
- entire span that can be perceived or detected by the eye at a given moment
- figure and ground relationship
- relationship between the meaningful part of a picture (the figure) and the background (ground)
- depth perception
- has monocular and binocular cues
- binocular disparity
- most important depth cue. Eyes view objects from 2 slightly different angles, which allow us to create a 3-D picture
- apparent size
- Depth cue. Gives clues about how far an object is if we know about how big the object should be.
- interposition
- depth cue. Overlap of objects shows which objects are closer.
- linear perspective
- depth cue. Gained by features we are familiar with, such as 2 seemingly parallel lines that converge with distance.
- texture gradient
- depth cue. How we see texture or fine detail differently from different distances
- motion parallax
- depth cue. How movement is perceived through the displacement of objects over time, and how this motion takes place at seemingly different paces for nearby or faraway objects.
- Eleanor Gibson and Richard Walk
- developed visual cliff
- visual cliff
- apparatus to study whether depth perception is innate. Thick layer of glass above surface that drops off sharply. Animals and babies were used as subjects and both groups avoided moving into the "cliff" area
- afterimages
- aka McCollough effect. Perceived because of "fatigued receptors". Because our eyes have a partially oppositional system for seeing colours, such as red-green receptors, once one side is overstimulated and fatigued, it can no longer respond and is overshadowed by its opposite. Explains why you see a dark afterimage after staring at a white light.
- dark adaptation
- result of regeneration of retinal pigment
- mental set
- factors into why we see what we expect to see
- Pragnanz
- overarching Gestalt idea that experience will be organized as meaningful, symmetrical, and simply whenever possible.
- closure
- Gestalt idea describing the tendency to complete incomplete figures
- proximity
- Gestalt idea describing the tendency to group together items that are near each other
- continuation
- aka good continuation. Gestalt idea describing the tendency to create a whole or detailed figure based on our expectations rather than what is seen.
- symmetry
- Gestalt idea describing the tendency to make figures out of symmetrical images
- constancy
- Gestalt idea describing how people perceive objects in the way that they are familiar with them, regardless of changes in the actual retinal image. e.g. book is perceived as rectangular in shape no matter what angle it is seen from.
- size constancy
- e.g. knowing that an elephant is large no matter how it might appear
- color constancy
- e.g. knowing the color of an object even with tinted glasses on
- minimum principle
- tendency to see what is easiest or logical to see
- ambiguous figures
- classic illusions which can be perceived as 2 diff things depending on how you look at them
- figure-ground reversal patterns
- classic illusions which are ambiguous figures, such as the Rubin vase. Can be perceived as 2 diff things depending on which part you see as the background
- impossible objects
- classic illusions which are objects that have been drawn and can be perceived but are geometrically impossible
- moon illusion
- classic illusion that shows how context affects perception. Moon looks larger when we see it on the horizon than when we see it in the sky. This is because the horizon contains visual cues that make the moon seem more distant than the overhead sky. In the overhead sky, we cannot correct for distance when we perceive the size of the moon because we have no cues to work with.
- Phi phenomenon
- classic illusion in which there is a tendency to perceive smooth motion. Explains why motion is inferred when there actually is none, often by the use of flashing lights or rapidly shown still-frame pictures. This is "apparent motion"
- apparent motion
- motion is inferred when there is none
- Muller-Lyer illusion
- most famous visual illusion. 2 horizontal lines of equal length appear unequal because of the orientation of the arrow marks at their ends. Inward facing arrowheads make the line appear shorter than another line with outward facing arrowheads.
- Ponzo illusion
- classic illusion in which 2 horizontal lines of equal length appear unequal because of 2 vertical lines that slant inward
- autokinetic effect
- classic illusion in which a single point of light viewed in darkness appears to shake or move. Happens because of the constant movements of our own eyes.
- Purkinje shift
- classic illusion in which perceived color brightness changes with the level of illumination in the room. With lower levels of illumination, the extremes of the color spectrum (especially red) are seen as less bright.
- pattern recognition
- most often explained by "template matching" and "feature detection". In order to pick out the letter o out of a page of letters, we would probably first concentrate only on letters with rounded edges and then look for one to match a typical o.
- Robert Fantz
- found that infants prefer relatively complex and sensical displays
- absolute threshold
- minumum amount of a stimuli that can be detected 50 percent of the time
- differential threshold
- aka just noticeable difference or jnd. Minimum difference that must occur between 2 stimuli in order for them to be perceived as having different intensities.
- E.B. Weber
- defined the differential threshold, aka jnd
- terminal threshold
- upper limit after which the stimuli can no longer be perceived. e.g. highest pitch sound a human can hear (the lowest pitch would be the absolute threshold)
- Weber's law
-
applies to all senses but only to a limited range of intensities. States that a stimulus needs to be increased by a constant fraction of its original value in order to be noticed as noticeably different. Formula is:
K(the constant factor) = Δ I(increase in intensity needed for jnd) / I(original intensity) - Fechner's law
- built on and more complicated than Weber's law. Says that the strength of a stimulus must be significantly increased to produce a slight difference in sensation. Law is written as S(sensation strength) = k log R(a logarithm of the original intensity)
- J.A. Swet's Theory of Signal Detection (TSD)
- suggests that subjects detect stimuli not only becaue they can but also because they want to. Factors motivation into the picture, which changes the idea of purely mathematical equations and explains why subjects respond inconsistently.
- response bias
- Individuals are partly motivated by rewards and costs in detection. The interplay between response bias and stimulus intensity determines response
- false alarm
- saying that you detect a stimulus that is not there
- hit
- correctly sensing a stimulus
- miss
- failing to detect a present stimulus
- correct rejection
- rightly stating that no stimulus exists
- receiver operating characteristic (ROC) curves
- these curves are graphical representations of a subject's sensitivity to a stimulus
- simulations
- perceptual cues to make artificial situations seem real
- dichotic presentation
- often used in studies of auditory perception and "selective attention". A subject is presented with a diff verbal message in each ear. Often subjects are asked to "shadow" one of the messages to ensure that the other message is not consciously attended to
- shadow
- repeat
- subliminal perception
- perceiving a stimulus that one is not consciously aware of, such as the unattended message in dichotic presentation or visual information that is briefly presented.