4 / Sensation and Perception

What is sensation?

The stimulation of sense organs

What is perception?

The selection, organization, and interpretation of sensory input

For people to see, there must be […].

For people to see, there must be light.

What is light?

A form of electromagnetic radiation that travels as a wave, moving, naturally enough, at the speed of light. 

Light waves vary in […] and in […].

Light waves vary in amplitude (height) and in wavelength (the distance between peaks).

What does saturation refer to?

The relative amount of whiteness in a color. 

As whiteness […], saturation […].

As whiteness decreases, saturation increases.

What is the lens?

A transparent eye structure that focuses the light rays falling on the retina. 

Describe nearsightedness.

In nearsightedness, close objects are seen clearly but distant objects appear blurry. 

Describe farsightedness.

In farsightedness, distant objects are seen clearly but close objects appear blurry. 

What is the pupil?

The opening in the center of the iris that helps regulate the amount of light passing into the rear chamber of the eye. 

What is the retina?

The neural tissue lining the inside back surface of the eye.
Absorbs light, processes images, and send visual information to the brain.

[…] occurs when the curvature of the lens adjusts to alter visual focus. 

Accomodation occurs when the curvature of the lens adjusts to alter visual focus. 

What are the two types of receptors that the retina contains?

Rods and Cones

What are cones?

Specialized visual receptors that play a key role in daylight vision and color vision.

What is the fovea?

A tiny spot in the center of the retina that contains only cones
Visual acuity is greatest at this spot

What is visual acuity?

Sharpness and precise detail

What are rods?

Specialized visual receptors that play a key role in night vision and peripheral vision

Dark adaptation is the process in which the eyes become […] sensitive to light in […] illumination.

Dark adaptation is the process in which the eyes become more sensitive to light in low illumination.

Light adaptation is the process in which the eyes become […] sensitive to light in […] illumination.

Light adaptation is the process in which the eyes become less sensitive to light in high illumination.

The collection of rod and cone receptors that funnel signals to a particular visual cell int he retina (or ultimately the brain) make up that cell’s […].

The collection of rod and cone receptors that funnel signals to a particular visual cell int he retina (or ultimately the brain) make up that cell’s receptive field.

What is the receptive field of a visual cell?

The retinal area that, when stimulated, affects the firing of that cell

What is the optic chiasm?

The point at which the axons from the inside half of each eye cross over and then project to the opposite half of the brain.

What are feature detectors?

Neurons that respond selectively to very specific features of more complex stimuli

What are two kinds of color mixture?

Subtractive and additive

How does subtractive color mixing work?

It works by removing some wavelengths of light, leaving less light than was originally there. 

How does additive color mixing work?

It works by superimposing lights, putting more light in the mixture than exists in any one light by itself. 

What does the trichromatic theory propose?

It proposes that the human eye has three types of receptors with differing sensitivities to different light wavelengths. 

Helmholtz believe that the eye contains specialized receptors sensitive to the wavelengths associated with red, green, and blue.

What is color blindness?

It encompasses a variety of deficiencies in the ability to distinguish among colors.

What are complementary colors?

Pairs of colors that produce gray tones when mixed together. 

What is an afterimage?

A visual image that persists after a stimulus is removed

The color of the afterimage will be the […] of the color you originally stared at. 

The color of the afterimage will be the complement of the color you originally stared at. 

What does the opponent process theory propose?

It proposes that color perception depends on receptors that make antagonistic responses to three pairs of colors.

What is a reversible figure?

A drawing that is compatible with two different interpretations that can shift back and forth

What is a perceptual set?

A readiness to perceive a stimulus in a particular way.

What does inattentional blindness involve?

It involves the failure to see fully visible objects or events in a visual display because one's attention is focused elsewhere

What is feature analysis?

The process of detecting specific elements in visual input and assemblind them into a more complex form

What is bottom-up processing?

A progression from individual elements to the whole

What is top-down processing?

A progression from the whole to the elements

The insight that the whole can be greater than the sum of its parts became the basic assumption of […].

The insight that the whole can be greater than the sum of its parts became the basic assumption of Gestalt psychology.

What is the phi phenomenon?

The illusion of movement created by presenting visual stimuli in rapid succession.

What are 6 principles formulated by Festalt psychologists that describe how the visual system organizes a scene into discrete forms?

1. Figure and Ground

2. Proximity

3. Closure

4. Similarity

5. Simplicity

6. Continuity

What is a perceptual hypothesis?

An inference about wht form could be responsible for a pattern of sensory stimulation

What does depth perception involve?

Interpretation of visual cues that indicate how near or far away objects are.

What are binocular depth cues?

Clues about distance based on the differing views of the two eyes

The principal binocular depth cue is […].

The principal binocular depth cue is retinal disparity.

What does retinal disparity refer to?

Refers to the fact that objects within 25 feet project images to slightly different locations on the right and left retinas, so the right and left eyes see slightly different views of the object.

What are monocular cues?

Clues about distance based on the image in either eye alone

What are pictorial depth cues?

Cues about distance that can be given in a flat picture

What are six prominent pictorial depth cues?

LIRTHL&S

1. Linear perspective 

2. Interposition

3. Relative size

4. Texture gradient

5. Height in plane

6. Light and Shadow

What is perceptual constancy?

A tendency to experience a stable perception in the face of continually changing sensory input

What does a visual illusion involve?

Involves an apparently inexplicable discrepancy between the appearance of a visual stimulus and its physical reality.

Sound waves are […].

Sound waves are vibrations of molecules.

Wavelengths of sound are described in terms of their […], which is measured in cycles per second, or […].

Wavelengths of sound are described in terms of their frequency, which is measured in cycles per second, or hertz (Hz).

Sound is conducted differently in each section.

• The external ear depends on the […].

• The middle ear depends on the […].

• The inner ear depends on […], which are finally converted into a […].

Sound is conducted differently in each section.

• The external ear depends on the vibration of air molecules.

• The middle ear depends on the vibration of movable bones.

• The inner ear depends on waves in a fluid, which are finally converted into a stream of neural signals sent to the brain.

What is the cochlea?

A fluid-filled, coiled tunnel that contains the receptors for hearing

What is the basilar membrane?

Runs the length of the spiraled cochlea, holds the auditory receptors, called hair cells.

What does the place theory propose?

Proposes that perception of pitch corresponds to the vibration of different portions, or places, along the basilar membrane.

What does the frequency theory propose?

Proposes that perception of pitch corresponds to the rate, or frequency, at which the entire basilar membrane vibrate.

Auditory localization

Locating the source of a sound in space

Gustatory system

The sensory system for taste

Sensory adaptation

A gradual decline in sensitivity to prolonged stimulation.

Ex) adaptation to a sour solution makes water taste sweet, whereas daptation to a sweet solution makes water taste bitter

NOTE: Can occur in senses other than taste. 

Olfactory system

The sensory system for smell.