Overview of Memory Atkinson-Shiffrin Model Sensory Signals Sensory Memory Short-Term Memory Long-Term Memory ATTENTION REHEARSAL RETRIEVAL

“Types” of Memory Sensory Memory –brief ( < 1 second) –preattentive / parallel processing (very large capacity)

Sensory Memory

Capacity Describe a simple experiment that could measure the capacity of “memory”

Capacity Describe a simple experiment that could measure the capacity of “memory” Briefly present some letters or digits and then ask the subject to report them –Called “whole report”

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Capacity “Recall as many letters as you can”

Capacity George Sperling - Systematic investigation of memory capacity –Result: subjects accurately recall 3 or 4 items –What can you conclude from this result?

Capacity Could it be that subjects had encoded but failed to retrieve the information?

Capacity For example: what if recalling interferes with memory? How could you modify the experiment to measure the instantaneous capacity, before any forgetting can occur?

Capacity Partial Report - briefly present letters or digits and ask subject to report only some of them “Report the letters in the row indicated by the arrow”

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Which Letters?

Capacity Partial Report Result: subjects can recall any 3 or 4 letters that are indicated by the arrow !

Capacity Partial Report Result: subjects can recall any 3 or 4 letters that are indicated by the arrow ! What does this mean about the capacity of memory?

Capacity There is some part of the perception system that stores huge amounts of information… –in fact, if only a single letter is probed, instantaneous capacity is seen to be unlimited

Duration There is some part of the perception system that stores huge amounts of information… But for how long? How would you design an experiment to measure the duration of this high-capacity memory system?

Duration There is some part of the perception system that stores huge amounts of information… But for how long? How would you design an experiment to measure the duration of this high-capacity memory system? Vary the onset of the probe

Duration Partial Report Probe Delay # of letters potentially recalled 500 ms0 msnever

Duration Partial Report Delay # of letters potentially recalled Interpretation: 1.Information dwells in a brief storage “buffer” 2.duration of storage lasts about 1/2 of one second 500 ms0 msnever

Iconic Memory a brief storage of “raw data” in the visual system

Echoic Memory Auditory information is stored in a similar sensory “buffer” –Echoic memory seems to last for several seconds

Properties of Sensory Memory 1.Brief (iconic ~500ms; echoic ~2 seconds)

Properties of Sensory Memory 1.Brief (iconic ~500ms; echoic ~2 seconds) 2.unlimited capacity

Properties of Sensory Memory 1.Brief (iconic ~500ms; echoic ~2 seconds) 2.unlimited capacity 3.pre-attentive

Next Time: Short-term memory