Cognitive Psychology: Connecting Mind, Research and Everyday Experience, 3rd Edition

Sensory Memory • 121

intervals. This is why these early fi lms were called “fl ickers,” a term that remains today,

when we talk about going to the “fl icks.”

SPERLING’S EXPERIMENT: MEASURING

THE CAPACITY AND DURATION OF THE SENSORY STORE

The persistence of vision effect that adds a trail to our perception of moving sparklers

and fi lls in the dark spaces between frames in a fi lm has been known since the early days

of psychology (Boring, 1942). But George Sperling (1960) wondered how much informa-

tion people can take in from briefl y presented stimuli. He determined this in a famous

experiment in which he fl ashed an array of letters, like the one in ● Figure 5.5a, on the

screen for 50 milliseconds (50/1000 second) and asked his participants to report as many

of the letters as possible. This part of the experiment used the whole report method; that

is, participants were asked to report as many letters as possible from the whole matrix.

Given this task, they were able to report an average of 4.5 out of the 12 letters.

● FIGURE 5.5 Procedure for three of Sperling’s (1960) experiments. (a) Whole report

method: Person saw all 12 letters at once for 50 ms and reported as many as he or she could

remember. (b) Partial report: Person saw all 12 letters, as before, but immediately after

they were turned off , a tone indicated which row the person was to report. (c) Delayed

partial report: Same as (b), but with a short delay between extinguishing the letters and

presentation of the tone.

(a) Whole report

X

A

C

M

F

D

X F

D Z

C

L

N

Z

T B P X A C

M

F

D

L

N

Z

T

B

P

(b) Partial report

Tone immediate

Immediate tone

X

A

C

M

F

D

L B

N

Z

T

B

P

(c) Partial report

Tone delayed

Delay

Delayed tone

Medium

Low

High

Medium

Low

High

X M

L T

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