Perception Exam 2

Grandmother cell

Jaragon of the field to stan for any cell that seems to be selectively responsive to one specific object

Agnosia

A failure to recognize objects in spite of the ability to see them. Agnosia is typically due to brain damage.

Feed-foward process

A process that carries out a computation one neural step after another, without need for feedback from a later stage to an earlier stage.

Illusory contours

A contour that is perceived even though nothing changes from one side of the contour to the other.

Gestalt psychology theory

The whole is greater than the sum of its parts

Gestalt principle: common region

Elements that move in the direction tend to group together

Gestalt principle: synchrony

Elements that change at the same time tend to group together

bayesian theory

a formal mathematical system that combines information about the current stimulus with prior knowledge about the world

FFA Fusiform face area

responds to faces more than other objects.

PPA Para hippocampal place area

Responds preferentially to places, such s pictures of houses.

EBA Extrastriate body area

Specifically involved in the perception of body parts

Geons

In biederman’s recognitions, which holds that object are recogized by the identities and relationships of their component parts.

Structural model of object recognitions

A description of an object in terms of the nature of its constituent parts and the relationships between those parts.

Template model of object recognition

A bunch of pictures in your head. Example- A letter E, would need o be at angles. All different sizes you need to have a different view you might have of that E. WAY TOO LONG OF A PROCESS

prosopagnosia

An inability to recognize faces.

Re-entrant process

Processes in the brain sends signals back downstream to earlier areas.

NOTE

We process global features of an image before local features. We will see the bigger more predominant object 1st before you see the little details making up that object.

Photopic

DAYTIME

Scotopic

Nightime

Principle of univariance

The fact that an infinite set of different wavelength-intensity combinations can elicit exactly the same response from a single type of photoreceptor. One photoreceptor type cannot make color discriminations based on wavelength

Metamers

Stimuli that are physically different but produce the same perception.

Number of lights needed to match any color humans can see

3

Cone-opponent cells

The kind of cells in the LGN that compute chromatic differences.

Opponent color theory

Perception of color is based on the output of 3 and each of these are opponents between two colors. Red-Green line, Blue and yellow line, Black and white line.

Additive color mixing

A mixture of lights. If light A and Light B are both reflected from a surface to the eye, in the perception of color the effects of those two lights add together.

Subtractive color mixing:

A mixture of pigments. If pigments A and B mix, some of the light shining on the surface will be subtracted by A, and some by B. Only the remainder will contribute to the perception of color.

Rod monochromat

Has no cones of any type; truly color-blind and very visually impaired in bright light.

Color contrast

A color perception effect in which the color of one region induces the opponent color in a neighboring region.

Color constancy

The tendency of a surface to appear the same color under a fairly wide range of illuminants.

Color assimilation

A color perception effect in which two colors bleed into each other, each taking on some of the chromatic quality of the other.

Steps in color perception: detection, discrimination, appearance

1. Light is differentially absorbed by three photopigments in the cones. 2. Differences are taken between cone types, creating cone-opponent mechanisms, important for wavelength discrimination.  3. Further recombination of the signals creates color-opponent processes that support the color-opponent nature of color appearance.

Binocular summation

The combination of signals from each eye in ways that make performance on many tasks better with both eyes than with either eye alone.

Binocular disparity

The differences between the two retinal images of the same scene.

Metrical depth cues

A depth cue that provides quantitative information about distance in the third dimension.

Nonmetrical depth cue

A depth cue that provides information about the depth order but not depth magnitude.

Texture gradient

A depth cue based on the geometric fact that items of the same size form smaller, closer spaced images the farther away they get.

Familiar size

  A cue based on knowledge of the typical size of objects.

Vanishing point

The apparent point at which parallel lines receding in depth converge.

Convergence

The ability of the two eyes to turn inward, often used to focus on nearer objects.

Linear perspective

 Lines that are parallel in the three-dimensional world will appear to converge in a two-dimensional image as they extend into the distance.

Pictorial depth cue

A cue to distance or depth used by artists to depict three-dimensional depth in two-dimensional pictures.

Motion parallax

Images closer to the observer move faster across the visual filed than images farther away.

Accommodation

The process by which the eye changes its focus (in which the lens gets fatter as gaze is directed toward nearer objects).

Free fusion

The technique of converging or diverging the eyes in order to view a stereogram without a stereoscope.

Random dot stereogram

A stereogram made of a large number of randomly places dots.

Correspondence problem

In binocular vision, the problem of figuring out which bit of the image in the left eye should be matches with which bit in the right eye.

Stereopsis

The ability to use binocular disparity as a cue to depth

Attention

Any of the very large set of selective processes in the brain.

Selective attention

The form of attention involved when processing is

Invalid cue

when its wrong

Valid cue

when its right

Spotlight of attention theory

Visual focus can move from pints to points. Where you are looking at, that’s where your attention is focused on.

Diatractor

In visual search, any stimulus other than the target. Noise when seeking its signal

Feature search

Search for a target defined by a single attribute, such as a salient color or orientation.

Salience

The vividness of a stimulus relative to its neighbors.

Parallel search

In visual attention, referring to the processing of multiple stimuli at the same time.

Conjunction search

Search for a target defined by the presence of two or more attributes.

Treisman’s feature integration theory

Limited set of features that can be processed in parallel.

Illusory conjunction

An erroneous combination of two features in a visual scene.

Response enhancement with attention

when you are paying attention to something you are going to have that bigger response, the more you attend to it.

Neglect

 In visual attention. The inability to attend to or respond to stimuli in the contralesional visual field.

Line cancelation test

Line circles, letters, or stars are drawn in random positions on a sheet of paper and presented to patients who are asked to cancel or cross out all the targets.

Spatial layout

The description of the structure of a scene without reference to the identity of specific objects in the scene.

Change blindness

The failure to notice a change between two scenes.

Inattentional blindness

A failure to notice or at least report a stimulus that would be easily reportable if it were attended.