Sensation and Perception

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I. Overview of Sensory Information Processing

A. Stimulus energy

light, sound, kinetic, thermal, etc.

not all energy can be sensed (e.g. UV light)

B. Transduction

conversion of stimulus (physical) energy into neural impulses

we can only perceive things that have been transduced

C. Iconic/Echoic Storage (ST memory stores)

visual and auditory information is stored to allow for more complex processing (takes time)

iconic (visual)--1/4 of a second, holds and integrates with incoming info

echoic (auditory)--3-4 seconds, e.g. recognizing what someone says just after they say it (when you're asking "what?")

II. Threshold--minimum amount of physical energy required to produce a conscious sensation

Method of Limits--experimental technique used to determine the sensory threshold; tone is played at varying intensities, starts at lowest intensity and trial stops when subject reports that they can hear the tone; next trial starts at highest intensity and stops when subject reports that they can no longer hear the tone; trials are repeated and then averaged to get an estimate of the threshold

A. Defined

Supraliminal--can produce conscious sensation; above threshold

Subliminal--cannot produce conscious sensation; above threshold

Semantic priming--flashing "doctor" subliminally primes for target stimulus "nurse"; reduces response time; RT(related)<RT(unrelated)

III. Signal Detection Theory--can be applied to decision making situations

A. Elements of Decision

Sensitivity--difference in older/younger adults

Response bias--all the things that influence how you respond but are not sensory

B. Signal and Noise distribution

subjects sits in a room and reports whether or not they heard a tone; the tone is low intensity, sometimes people get it wrong

the same tone will not always produce the same psychological intensity; due to external noise that fluctuates and internal noise, our sensory systems do not always produce the same amount of action potentials

IV. Iconic and Echoic Store

Sperling (1960): partial report method; subject were shown a grid of letters, asked to recall either the whole thing or just a row; did much better when only having to recall one row; the iconic store faded fast when the letters were all being recited