Psych 111 - Ch.6 - Sensation and Perception

Transduction

the process of converting one form of energy into another that are brain can use

all of our senses preform 3 basic steps:

1. receive sensory stimulation, often using specialized receptor cells

2. Transform that stimulation into neural impulses

3. Deliver the neural information to our brain

absolute threshold

the minimum stimulation needed to detect a particular stimulus 50% of the time

difference thresholds or just noticeable difference

the minimum stimulus difference a person can detect half the time

Cochlea

a small shaped tube in your inner ear

loudness

detected by the number of activated hair cells, louder sounds activate more hair cells

receptor cells for vision

photoreceptor cells (rods & cones) in the retina trigger chemical changes when exposed to light energy

receptor cells for hearing

hair cells

receptor cells for smelling

olfactory receptor cells at the top of each nasal cavity. These receptors respond selectivity to different odor molecules and alert the brain through axon fibers

receptor cells for tasting

taste receptors are located in taste buds on the tounge and reproduce every week or two

retina

the multilayered tissue lining the back inner surface of the eyeball, where light energy is converted into neural impulses

Ganglion cells

activated by bipolar cells, axons form the optic nerve

optic nerve

transmits information to the thalamus and then to the visual cortex in the occipital lobe of the brain

*the blind spot is the area where the _____________ leaves the eye, containing no receptor cells

fovea

the retina's area of central focus, densely packed with cones

Trichromatic color vision theory

the retina has three types of color receptors (cones), each sensitive to red, green, or blue wavelengths. Combinations of these cones' stimulation create the perception of other colors

Opponent-process theory

color vision depends on three sets of opposing retinal processes: red-green, blue-yellow, and white-black. Neurons are "on" for one color and "off" for its opponent (ex. "on" by red, "off: by green)

Opponent-process theory

*this theory explains afterimages where staring at one color and then looking at a white surface causes the opponent color to appear

perceptual constancy

a top down process that allows os to recognize objects without being decieved by changes in color, brightness, shape, or size, regardless of viewing angle, distance, or illumination

color constancy

Perceiving familiar objects as having consistent color, even under changing illumination, due to the brain's computations of light reflected by an object relative to its surroundings

Brightness constancy (lightness constancy)

Perceiving an object as having a constant brightness even as its illumination varies, depending on its relative luminance (amount of light reflected relative to surroundings)

Shape constancy

Perceiving the form of familiar objects as constant even when the retinal images change (e.g., a door opening still appears rectangular)

Size constancy

Perceiving an object as having an unchanging size, even when its distance from us varies, often influenced by the interplay between perceived distance and perceived size (e.g., the Moon illusion)

sensory adaptation

the diminished sensitivity to an unchanging stimulus due to constant exposure, as nerve cells fire less frequently

This adaptation allows us to focus on informative changes in our environment rather than constant, uninformative stimul

visual cliff

experiments by Gibson and Walk showed that most infants and mobile newborn animals perceive depth and are wary of heights

monocular cues

Depth cues available to each eye separately, used for judging distances of objects further away where retinal disparity is minimal. Examples include:

Relative height

Relative size

Interposition

Linear perspective

Light and shadow

Relative motion

binocular cues

Depth cues that depend on the use of two eyes, used for judging the distance of nearby objects

Convergence

The inward angle of the eyes focusing on a near object

Retinal disparity

The brain compares the slightly different images received by each retina to judge how close an object is; greater __________ indicates a closer object

depth preception

the ability to see objects in three dimensions, allowing us to estimate distance from two-dimensional retinal images

yes

Is depth perception innate?

perceptual constancy

Our perception of an object's features remains constant even when our viewpoint (and the proximal stimulus) changes.

-Perception of size doesn't change with distance.

-Perception of shape doesn't change with viewing angle.

-Perception of darkness/color doesn't change with light.