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

Sensory Memory Supplementary reading: Cognition (on reserve) Averbach and Sperling (course pack) Part 1

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”

Capacity +

F S F E G S A U T O C G +

Capacity “Recall as many letters as you can”

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

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

Capacity For example: What if they forgot the information before they could report it? – You would get the same result! 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”

Capacity +

U E S B O D W A I B V S +

Capacity +

Which Letters?

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

Capacity Partial Report Result: subjects can recall any 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.Virtually unlimited capacity

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

Properties of Sensory Memory 1.Brief (iconic ~500ms; echoic ~2 seconds) 2.Virtually unlimited capacity 3.pre-attentive What happens if you attend to information in Sensory Memory?

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

Characteristics of STM Limited Capacity – George Miller – Subject is given longer and longer lists of to-be- remembered items (words, characters, digits) – Result: Subjects are successful up to about 7 “items” – Miller used the term “chunk” to refer to items in memory… » But what is a “chunk”?

Capacity and Forgetting from STM Limited Capacity – Recalling takes time !

Capacity and Forgetting From STM Naveh-Benjamin & Ayers (1986) Showed that apparent span of STM is reduced for items that take longer to say

Capacity and Forgetting From STM Brown (1958) and Peterson & Peterson (1959) Subjects given list of “trigrams” Rehearsal prevented by counting backward by threes Showed that duration of STM is on the scale of seconds Proportion Correct Delay (seconds)

Capacity and Forgetting From STM Rundus (1971) Long lists of “to-be- remembered” items Primacy Effect – participants more likely to recall first few items Recency Effect – participants more likely to recall last few items Probability of Recall Position in list

Capacity and Forgetting from STM Why do we “forget” from STM? – Does the memory trace decay? not likely because with very small lists (like 1 item) retention is high for long intervals

Capacity and Forgetting from STM Why do we “forget” from STM? – Does the memory trace decay? not likely because with very small lists (like 1 item) retention is high for long intervals – Instead, it seems that information “piles up” and begins to interfere

Capacity and Forgetting from STM Interference in STM is complex and specific