Sensation and Perception Exam 1

Sensation

The initial process of detecting and encoding environmental eneergy

Perception

the process of organizing and interpreting sensations into meaningful experiences

Structuralism

focused on discovering the basic elements and structure of perception, used introspection, fathered by Wundt

Gestalt psychology

perception of the envioronment with inherent organizational and relational properties, response to structuralism’s ignorance of the relations among stimuli, “the whole is greater than the sum of its parts”

Cognitive approach

perception is believed to be the outcome of a building process based on sensory information and strategies

Computational approach

perception is the result of an analysis performed on the retinal image

Neurophysiological approach

sensation and perception can be explained on the basis of neural and physiological mechanisms that serve the sensory systems

Reductionism

one can understand complex behavior by studying their underlying biological processes

Cognitive neuroscience

a multidisciplinary area of experimental psychology, neuroscience, and computer science; examines at a neural level how the brain performs perceptual-cognitive tasks

Neuron

basic element of the nervous system

Cell body

life support of the neuron, houses the nucleus, regulates chemical activity, collects information

Dendrites

receive information from other neurons

Axon

carries information from the cell body to other neurons

Terminal button

round swelling atthe end of axon that synapses with another neuron

Resting potential

inactive state of the neuron, around 70 mV

Action potential

electrical charge in the neuron that fires the neuron when the threshold of excitation (60 mV) is reached, causes neurotransmitters to be released in the synaptic cleft

Refractory period

period of neural inactivity following action potential

Synapse

junction between the terminal buttons and dendrite of two neurons

Neurotransmitter

chemicals that diffuse across the synaptic cleft and stimulate (excite or inhibit) the post-synaptic neuron.

Gyri

Ridges in the brain

Sulci

valleys in the brain

Four lobes of the brain

frontal, parietal, temporal, occpital

psychophysics

methods for quantitatively measuring the relationship between properties of the stimulus and the subject’s experience

absolute threshold

the smallest amount of stimulus energy necessary to detect a stimulus

Subthreshold

stimuli too weak to detect

Suprathreshold

stimuli above absolute threshold

Point of subjective equality

the point at which the stimulus is detected 50% of the time

Method of limits

stimulus presented in a stepwise ascending or descending order

Method of constant stimuli

stimuli presented in a random order, best method for accuracy, weakest for efficiency

Method of adjustment

observer slowly changes the stimulus in a continuous manner until it is detected, best for efficiency, worst for accuracy and subject variability

Difference threshold

a physical measure of the smallest decteable difference between 2 stimuli (quantifiable)

Just noticeable difference

a physiological measure of the smallest detectable difference between 2 stimuli (subjective)

Weber fraction

the amount of change necessary to detect a difference is proportional to the absolute magnitude of the stimulus (difference is relative, not absolute), ∆I/Is = k

Subliminal perception

stimuli are not consciously detected but exert some measurable influence on response outcomes

Lexical decision task

subject determines whether a stimulus is a word on non-word

Semantic priming

an experimental technique when one word primes the perception of another

Signal detection theory

detection of a stimulus depends both on the subject’s sensitivity and on their response criterion

Conservative

responding “yes” when the tone is loud

Liberal

responding “yes” when there is the slightest possibility of hearing the tone

Hit

responding “yes” when a stimulus is present

Miss

responding “no” when a stimulus is present

False Alarm

responding “yes” when a stimulus is not present

Correct Rejection

responding “no” when a stimulus is not present

Noise

extraneous background stimuli in a stimulus detection task

Criterion

the stimulus magnitude at and above which a subject will report a stimulus present in a SD task

D’

a quantitative term derived in an SD task that serves as a measure of the subject’s sensitivity to signal strength that is independent of response bias

Detection of the presence or absence of a stimulus is affected by…

Signal strength, expectancy, payoff reqard or punishment