Sensory Memory

The distinctions among the three structures is made on the basis of four characteristics: 1) capacity 2) duration

Types of codes, and 4) mechanisms of loss /forgetting

Step 1.Sensory Memory( 1 of 3 forms) Sensory memory

The sensory memories act as buffers for stimuli received through the senses. A sensory memory exists for each sensory channel:

iconic memory for visual stimuli, echoic memory for aural stimuli and haptic memory for touch. Information is passed from

sensory memory into short-term memory by attention, thereby filtering the stimuli to only those which are of interest at a given

time.

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Acts for a very few seconds and difficult to distinguish

from the act of perception. It is that very brief memory

that holds information after the physical stimulus is no longer present. Holds information in raw form rather than

changing it or making it more meaningful Encoding, storage and retrieval do not occur at this level. We are most often unaware of this memory. Short stimulus afterimage provides a brief exposure of items one would wish to process to STM.

Why do we need? 1) keep accurate record of physical stimulus for a brief moment while we select most important aspects for further processing. Brief imprint.This imprint is of all the stimuli that we cannot pay attention. 2) stimuli bombarding our senses are constantly changing. "Why do we need sensory memory" The "wh" sound gone by the time you hear memory. Need to retain wh pitch and compare it with the pitch at end of sentence.

Examples: Iconic or visual memory: swing a flashlight in a dark room and you will perceive a complete circle

Echoic or auditory memory: Pound rhythm on desk

Touch, smell, taste. Rub palm over desk edge.

Research:

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1) Iconic: Visual sensory memory--whole vs partial report Whole typically generates 4 to5

Sperling (1960) T-scope

1) chart flashes for 1/20 second

2) high medium low tone sounds and indicates which line should be reported

3) reports top line S, Q, H

Research summary: Capacity: 9-10 items for 1 second

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See overhead 1 and 2

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2) Echoic memory or auditory sensory memory

Darwin, Turvey and Crowder (1972) Partial report procedure

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Results: differences between echoic and iconic: echoic memory capacity seems to be about 5 items which is considerably less than visual but echoic memory is longer ( 2 secs vs 1 sec)..

Half life capacity and .5 vision 1 second and audition is 2 seconds.