The effects of concurrent secondary tasks on the use of imagery in a free recall task

Acta

Psychologica

53 (1983)

231-241

231

North-Holland

THE EFFECTS OF CONCURRENT SECONDARY THE USE OF IMAGERY IN A FREE RECALL TASK W.A. MATTHEWS

*

Unrversrtg of Southampton,

UK

Accepted

February

An attempt to that encoding effects

dimension

of items during

of high

trials,

can

in the

Paivio’s

be ascribed High-l

of secondary

secondary

Recall

materials.

An

One secondary

of the High-I

items

task. As performance

it was accompanied

view that to the

the superior

fact

that

by improved

impaired

to prevent

compared

investigated of equal

the

numbers

the use of imagery

in the presence

task improved

of the High-l

words

as an additional

which

lists consisting

task was intended

was selectively

of High-I

is available

is reported

of word

on the secondary recall

recall

imagery

experiment

task on the free recall

and low imagery.

acquisition.

inhibiting

to evaluate

words

of two types

ON

1983

was made

of Low-l

TASKS

in some

of the image subjects

over 3

words.

It is widely recognised that the extent to which words are capable of evoking visual images reliably predicts the efficiency with which they will be recalled. This has been fully documented in varied learning and recall contexts by Richardson (1980). Paivio (1971) has argued that such findings are attributable to the fact that imagery provides an additional dimension to the normal verbal/semantic code along which the items can be coded. Thus two codes are available for the processing of high imagery words (High-I), one based upon imagery and the other upon verbal/semantic characteristics, but only a single verbal/semantic code is thought to be available for low imagery items (Low-I). However the fact that ratings of words on the dimensions of imagery and concreteness are highly correlated, allow alternative explanations to that provided by Paivio for the facilitation found in recall. Baddeley et al. (1975) have proposed that reductions in concreteness ratings lead to differences in the encoded verbal/semantic characteristics and that * Author’s

address:

ton SO9 5NH.

W.A.

Matthews.

Dept.

of Psychology,

University

of Southampton,

UK.

OOOl-6918/83/$3.00

‘C 1983, Elsevier

Science

Publishers

B.V. (North-Holland)

Southamp-

imagery

processes

have

little

direct

effect

A number of investigations have elucidate this issue using performance

on either

coding

or recall.

been carried out to attempt to on a concurrent secondary task

during either learning or recall. as a means of minimising the influence of imagery processes. While differing in detail. the studies have been designed to test the hypothesis that the facilitative effects of imagery on learning or recall are reduced when the learner is carrying out a concurrent task which involves visual/imagery processes. However the results of these studies have produced contradictory outcomes. Janssen (1976a. b) reported a small but statistically significant selective reduction in the recall of High-I words when the secondary task required the subject to report which item of a visually presented digit pair was absent. Auditory presentation of the digits produced no such effect. Similar findings were reported by Atwood ( 197 1) who employed the same secondary task as Janssen. However attempts to replicate Atwood’s findings have been unsuccessful (Baddeley et al. 1975). Failures to obtain selective interference in the recall of High-I words have been reported by Baddeley et al. (1975) and Warren (1977). using a pursuit-rotor tracking track as the source of interference. Baddeley et al. reported three experiments. The first two were aimed at establishing that a pursuit rotor task did interact with other tasks that used the visual modality by measuring error rates on the tracking task while carrying out either visual or verbal secondary tasks. It was claimed that the results of these experiments indicated that time on the target declined while carrying out visual tasks and that this established the appropriateness of the task as one that interfered with visual/imagery processes. However there are problems with this view. for in experiments 1 and 2, subjects were required to stay on target for a longer period while carrying out the visual component of the secondary task than the verbal component. Thus task difficulty was not equated and it is a moot point whether the time differences on target are a function of the modality of the secondary task, as is claimed, or of the differences in time required to be on target during the visual and verbal tasks. The third experiment then used tracking as the secondary task during the paired-associate learning of verbal material of varying imagery values. The results of experiment 3 in which subjects learned lists of 15 noun-adjective pairs which were either concrete or abstract (i.e. of High-I or Low-I values) in the presence or absence of the tracking task revealed no selective interference in the recall of the concrete (High-I)

word pairs. In the absence of the tracking task, performance was superior on the concrete (High-I) items (88% correct compared to 38%) but in its presence, performance declined by a similar percentage in both concrete (High-I) and abstract (Low-I) conditions. This failure to obtain an interaction between tracking task and the recall of High I items was repeated by Warren (1977: exp. 3) who studied the free recall of a mixed list of High-I and Low-I words. Baddeley et al. used these results to question Paivio’s claim that dual coding was the basis for the reliably obtained superiority in recall of High-I over Low-I items. They attempted to reconcile their failure to find differential loss of concrete (High-I) items in the presence of the tracking task by suggesting that there are different consequences of the correlated measures on the imagery and the abstractness-concreteness dimensions. It was claimed that the abstractness-concreteness dimension reflected the absence or presence of semantic features that were encoded automatically during learning but that imagery, as it increased. allowed the operation of optional strategies. The facilitation in recall of the concrete (High-I) words could be ascribed to automatically used semantic processes: the failure to find loss of the concrete (High-I) items in the presence of the secondary task was due to the fact that subjects were not using imagery-based strategies. However their failure to find any differential loss of concrete (High-I) items may be due to the inappropriateness of the pursuit-rotor task, as a source of interference. Thus the secondary task used by both Baddeley et al. and Warren may not have prevented the generation and use of images and may have done no more than provide general interference for both High-I and Low-I items. This experiment reports an attempt to throw more light on this issue using the effects of different secondary tasks from those mentioned earlier. The word lists contained 10 High-I and 10 Low-I items and on the assumption that the ‘image’ is a component in the encoded version of each item which is then used to facilitate recall, sought to prevent the formation and/or use of images with the High-I items during presentation. In addition, an assessment of the effects of practice on the secondary task on subsequent recall was included by having 3 presentation trials on each list. The order of the presented items was randomly re-arranged on each trial to inhibit the use of grouping strategies based on serial order or imagery based linking strategies. The characteristics of the secondary task were the critical problems

for the task must be an effective inhibitor of the formation of images during learning; must allow some measure of the accuracy of the performance of subjects; and must allow the derivation of a secondary control task which is as similar as possible to the experimental task in terms of perceptual and motor demands. but does not require the maintenance of image inhibiting activity during the encoding operations on the words. This was accomplished by visually presenting a series of outline shapes in synchrony with the auditory presentation of the items in the word lists. In each sequence there were 4 blocks of 5 related shapes; in some conditions. 2 of the 4 shapes that were presented at 5 set intervals after the presentation of the first slide (which was one of a square, rectangle, triangle or circle) would reconstruct the first shape when they were superimposed. The 4 shapes were designed to be difficult to label verbally and with size and orientation as well as shape being relevant dimensions. the maintenance of the information by image-like representation was necessary. Such images had to be retained throughout the 5 slide series as the second slide of any pair that reconstituted the first shape always occurred in the 5th position. The subject had to indicate a decision (yes/no) after each successive set of 5 slides so giving a measure of performance accuracy. The control task involved the presentation of shapes in exactly the same way. In this condition a small break might occur anywhere in the contour and the subject had to scan the shape, identify the presence or absence of a break and count how many slides in each set of 5 contained such contour breaks. This number, which varied between 0 and 3 had to be written after each successive set of 5 items. Thus the input and output requirements in the secondary tasks were almost identical and each task contained a memorial component; they differed in the characteristics of that memorial component with the experimental condition requiring the retention of images. If, therefore, the first of these secondary tasks utilised image processing capacity, performance on the High-I items should be worse in the experimental condition than in the control condition. Low I items should be little affected (if at all) by these variations, if Paivio’s views on dual coding have some validity. A pilot experiment using 34 subjects suggested that the secondary tasks were effective in the ways suggested above, and following minor modifications to the secondary task, the experiment reported here was carried out.

235

Method Material.7 (u) Lists

Two lists of 20 bisyllabic nouns were constructed from the norms produced by Toglia and Battig (1978). In each list were IO words that were highly rated on both imagery (I) and concreteness (C), and 10 words that were low on both scales. The lists were very similar on familiarity (FAM) ratings. The mean values were: List A:

High-I Low-I List B: High-I Low-I

5.98; 3.54; 5.94; 3.47;

High-C Low-C High-C Low-C

6.18; 3.49; 5.98; 3.59:

FAM FAM FAM FAM

6.25. 5.74. 6.21. 5.78.

The lists were recorded on magnetic tape, in a male voice at a rate of one word every 5 sec. The order of High-I and Low-I items was generally alternating, with occasional variations to destroy a regular pattern, but similar numbers of High-I and Low-I items were present at the beginnings and ends of the lists. There were three presentations of each list with word order being randomised between presentations within the constraints specified above. (h) Slides (i)

Three sets of 20 outline shapes were constructed and prepared as slides for projection by a Kodak Carousel projector. Within each set of 20 were 4 groups of 5 related shapes, with each group constructed on the following principles. The first of the 5 slides contained an outline shape; 4 other slides followed. with each containing an outline of a different component of the first presented shape. In some groups, the combination of two of these 4 outlines with shape, orientation and size relevant attributes reconstructed the first presented shape. In other groups the 4 slides did not contain any outlines which reconstructed the initial shape. Where 2 outlines reconstituted the initial shape, the second of the 2 outlines always occurred on the 5th slide with the other member of the pair occurring randomly in positions 2, 3. or 4. The 4 outlines used in the 1st. 6th, I Ith and 16th position in each set were square, circle, triangle and rectangle with order varying between sets. The components in the other positions were designed to be difficult to describe by a simple verbal label. Within each set, 2 of the 4 groups could produce a reconstructed complete shape and 2 could not. The position of these 2 groups in the set, the shapes that could be reconstructed, and those that were effective in producing a reconstruction were varied between the 3 sets. (Matching task.) (ii) 3 sets of 20 outline shapes were constructed and prepared as slides. The same outlines were used as in b(i) but in some instances, there was a break in the contour of the outline. The break was located in various positions and was never greater than 4% of the length of the contour. The 4 groups of 5 slides that were related to the square, circle, triangle and rectangle were mixed together in this condition; what was varied in

each

group

of 5 slides

was

contour.

The

slides.

(Counting

task.)

(iri)

2 practice

sequences

described

number

in (b) (i) and

40 undergraduates of 20 as part

Each

S had

3 learning

was

presented

outline and

boxes

whether how

was

allowed

was

many

before

the

box

counting

of the error

second

Ss were

told

a subsequent nously

with

square,

circle.

that them

their

item

stood

counting count

in each

task.

on the response with

words

was

a 5 min

of these

were

told

of these sheet given

interval

and

when between

sheet

presentations trials

slide

Ss had

to indicate

of the

5th slide

group.

to indicate

List A wab used

had the

the matching

order

effects

secondary within

of an

a response

5th slide

each

contours.

group

task.

*as

was task

for the

condition

reversed.

carried

from

other.

;I

by

the first

3% of each

An

out

to the

giving

no

to

for

they

slides into

in each

on

auditorily

presented

that

and

they

to decide

for

synchrowc)uld

was

20th

see a

visually

in each

them

shape

but they

projected

and

the signal.

were

to

IO practice

01

Before

the

shape,

to

to v. rite the number

Ss understood

of the task.

size and

by an assistant

prc>Jectcd.

of 5 slides that

2 of

The occurrence

signalled

contour

and

any

slides.

sheet. were

to ensure

lrhcther

not only

15th and

the outlines

sequence

the 2 components

told

the response

broken

gave

presented being

\\ere

account

IOth,

where ;I

items

1at. 6th. 1I th and 16th positions.

of 5 slide5

condition

initial

to the Lvords being

space

the assistant

in each

the

group

to the visual

taking

to look

each

(O--3) after

were

of the 5th.

close

after

the projection

transfer.

shape.

occurred

of the 3 matching

transfer

folIoming

blocks

each Lvord

each

other

four

of the group,

after each

representing

on each

in the appropriate

Ss were

how many

group5

conditions.

trial

rows

in one of the

the presentation

in front

principles

learning

with

One

the matching the

On each

task

5’ was

broken

to attend

test,

the critical

After

a tick or a cross

the last who

to scan

reconstructed

was

or rectangle

was

of 5

1x35 required uaa

had

the

counting

of the

condition.

asymmetrical

recall

Before

triangle

task

the

presentation

a digit

The decrements

task

free

and

reconstructed

of asymmetrical

their

the words.

orientation. enter

that

in the

group

as Ss in 2 separate

sheets

alternative

had

decrements

position.

written

using

front

During

to enter

for of

rate

to the possibility

In

of 5 slides

presence

presentation

support

slides

condition;

comparison

this

a Yes/No

Ss had

in the group

of

with

were 4 boxes

list B for the counting

assessment

acted

test.

5 sec.

of 5 slides.

under

trials

the

a break

3 in each

constructed

response

the recall

for

of which

blocks

in each

shapes and

contained 0 and

of the matching

separate

for

visible

in each

the counting

matching

each

on

2 of the 4 presented

During

were

of Southampton

under

recall

representing a tick

which

between

requirement.

free

which

of 6 rows

to place

each

for 5 sec. Synchronised

shape

consisting

IO slides

of

trials

set

60

of figures varied

of the University

written

presentation.

number instances

(b) (ii) above.

of a course

Immediate

the

of these

slidus the task.

paired There

Thus in the matching task, visual information that could not be adequately verbalised had to be retained for use at 4 points during the presentation of the word lists of High- and Low-l items, whereas in the counting task retention of visual information was not required during the presentation of a similar list, but the observation requirements and temporal constraints were identical and response requirements almost so.

Results

and statistical

treatments

Earlier work reported by Richardson (1978: exp. 3) has indicated that facilitative effects of imagery are absent in the free recall of recency items (Waugh and Norman 1965; Tulving and Colotla 1970). Estimating the size of the recency component in these 20 word lists was carried out using 3 methods. Method 1 employed the procedures and values specified by Tulving and Colotla (1970) who proposed that an item was retrieved from the recency component if no more than 6 items intervened (as either input or output) between presentation and recall. In the 2 remaining methods, the recency component was estimated using the criterion of either the last 3 presented items recalled in any of the first 3 positions of the recall protocol (Method 2). or the last 2 presented items recalled in the first 2 positions in the recall protocol (Method 3). The general pattern of the derived data was similar using all methods; however the 2 latter methods are likely to include larger numbers of recency items which should remain unaffected by the secondary task so that trends in the data indicating the effects of secondary task on High-l items may become increasingly obscured as one moves from Method 1 to Method 3. Split-plot analyses of variance (Kirk 1968) were conducted on

5Mean number

of

4-

words

recalled 3-

2-

l-

~

I

-

Matchmg Counting

1

Tl

T3

T2 TEIIS

Fig.

1. Mean

Method

number

I: recency

of words items

recalled

excluded.

by trial

and

condition

(40 subjects).

Data

produced

by

the 3 forms very

of the data.

similar

based

and

on data

The

mean

pattern

scores

Significant with

effects

cases).

However,

effects

and

p < 0.01)

type

that

between

type

decreasing

were

I and task,

the

are

not

in fig.

analyses reported.

1. (A similar

trials

3. The

on the task

main

effects

significant

order

than

of

in both the main

( F( 1,38) = I 1.54,

I was significant

was

of

rather

more

p i 0.01)

> ~0.05

= 7.97. p < 0.05).

trials

with

= 196.52.

( F values

interactions

and

(F(2.76)

I and

p < 0.01)

( F(2.76)

for trials

not significant

is centred

of secondary

between

and

I( F( 1.38) = 21.24.

and

1 to trial

trial

secondary

effects

1 are presented

for

items

task

interest

between

as was

from

of secondary

I and 2 w’ere

by Methods As expected.

experiment.)

obtained Low-I

derived

reported.

use of Method

in the pilot

than

primary

that

interaction

the

improving

and

are

3 showed

were

recalled

performance

presentation,

by

on the data

I data

by Method

derived

being

based

Method

was obtained

main

items

from

derived

of results

High-I

The results

those

Finally.

(F(2.76)

the triple = 7.45.

p <

0.01). Performance counting

on the High-I

condition,

effects

focused

trials.

on

On trial

this

the

effect

I recall

items

in the matching

difference

decreased

of the

of the High-I

3. performance

was

better

15.05, p < 0.05).

With

the counting

items

on every

the Low-I

respectively, A

analysis

of

these

to an understanding

Low-I

items.

occurred

One

because

High-I

and

worse

if this were

performance

on

becoming

the

number

the case

a post

was

6.10

(Max

errors

was

3.25.

However.

already

rates.

A further

than

in the over

of the Low

on trial

2 but on

(F(1.76 =

items

superior

main

items

that

Low-I

18.80

on the High-I

on trials

I. 2 and

3

there

which

is

into

Ss within

group

rate

It is clear

each data

by type mean from

ment

in the recall

while

carrying

out

showing

and

the figure

little task

this

that

task

should

practice

make

improved

processing

a positive

items

resources

relationship

between

out based

on

group

the mean

number

of

in the other

group

the mean

number

of

main

items

the counting

task.

mean

by

replicated

group

showed

of error

was carried

being

6.0. 4.0 and

2.3

An analysis

of

and

interaction

recall

effects errors

scores.

differences of the data

3 with

task

rates

in error

I by trials

arrangement

the significance

or interactive error

significant

by trial

was carried

of matching

variation

the low error

of the High-I

2 blocks

of variance

of 7 with

the earlier

from

High-I

on the learning

In one

no significant

of secondary

scores

is that

to additional

task.

the analysis

3 groups

repeated

on the

in the recall

produce

of Ss as a function

21 Ss arranged

trials

of the High-I

concentrated

possibility

of Ss into

3 trials)

were

rearrangement

and

scorers

leading

information

efficiency.

although

and

The

thus

on the matching

= 12 over

reported,

on these

the higher

some over

task

so this should task

out using

error

Low-I

in the acquisition

improvement

hoc rearrangement made

errors

provide

involved

An alternative

task,

secondary

of errors

levels

then

task.

If this were

and

Accordingly,

p c 0.01).

the

than

of simple

difference

than

was significantly

may

is that

secondary

available.

efficiency

variance

recall

out of the secondary

on the secondary

errors

with

items

(F(1.76) = 18.80. 22.98,

changes

possibility

Ss opted

most

cant

on

was significantly

of the processes

component;

recall

task,

trial

worse

A test

task

High-I

was

trials.

p < 0.01).

detailed

relevant

the

items

on the

than

and

matching

condition over

(F(1.76) = 14.19, p < 0.05). There was no significant

I items trial

but

added (F(4.36)

a signifi= 40.00.

are presented

in fig. 2.

a substantial

improve-

at least

as efficient

as it was

239

2(a) Matching

condltlon

,

6-

5-

of words recalled

4-

3-

21 LOW -1

~ l-

High

-

-

- - - -

TI

numbers

M&urn Low

of errorS

number number

of errors

of errors

TZ

2(b)

Counting

T3

condltlon

7-

6-

5Mt?W number of words recalled

4-

3-

2”

__ l-

-

High -

- - - -

Tl

LOW -1 number

Medium Low

of errors

number

number

of errors

of errors

T2

T3

TWIS

Fig. 2. Mean subjects). counting

Data

number

of words

produced

condition.

recalled

by Method

by trial. I: recency

condition. items

and

excluded.

error 2(a):

rate

on matchmg

matching

condition;

task

(21 2(b):

Discussion This experiment has demonstrated that High-I words are better recalled than Low-I words when presented in a mixed list with the subject simultaneously carrying out a secondary visual task which does not require the retention of images for its completion (i.e. the counting task). It could be argued that in its essentials, the counting task had similar characteristics to the pursuit-rotor tracking task used by Baddeley et al.. in that visual scanning of the presented stimuli was required and a response had to be made. albeit intermittently. rather than continuously. What these secondary tasks did not require was the generation and maintenance of images, and the fact that selective interference with High-I words failed to appear in both cases provides support for the view that the task used by Baddeley et al. was simply inappropriate for the purpose, and that their results have no direct bearing on the issues raised by Paivio’s dual coding hypothesis. Allport (1980) has suggested that there is a need to specify the components of the cognitive system in a far more precise way than has been attempted (as well as emphasising the difficulties of investigating such systems) and it seems reasonable to expect that any investigation of the suppression of imagery processes using secondary task techniques should involve imagery processes and not just the visual system in both tasks. When this was done in the matching task in this experiment. so that images had to be retained during the presentation of the High-I and Low-I words, a selective loss of the High-1 items in the non-recency part of the list was obtained, and prevented the appearance of the recall superiority of High-I items that is normally found without such interference (e.g. Warren 1977; Baddeley et al. 1975). This result lends support to the view that the availability and use of images is at least one component in the acquisition and recall of High-I words. However, this experiment included three trials in each condition to allow the time course of such interference to be investigated. When these data were considered along with the error rate on the secondary matching task, it became clear that in addition to the expected improvement over trials on all items, there was a differential improvement in the recall of the High-I items as the error rate on the matching task decreased. Thus, in addition to confirming the earlier demonstration of selective interference by Janssen which was shown on a single presenta-

tion

and

recall

trial,

this

pattern

of performance

can persist

over three

indicates

with imagery

on the petence

secondary task decreases, indicating a higher degree on that task, so recall of High-I words improves. This

that capacity becomes increasingly dimension as error rate declines

trials.

that

ference

However.

inter-

as error

rate

of comsuggests

available to use an image encoding on the secondary task and provides

support for a view which claims that imagery that acquired from a verbal-semantic code recall.

based information adds to to facilitate learning and

References Allport.

D.A.,

London: .Atwood.

1980.

‘Attention

Routledge

G..

and

and

Kegan

performance’.

In:

G.

Claxton.

rd..

Cognitive

psychology.

Paul.

1971. An experimental

study

of visual

imagination

and

memory.

Cognitive

Psychol-

and usual

-orking

memory’.

V. London:

Academic

ogy 2. 239-289. Baddelq. In:

A.D.. P.M.A.

S. Grant. R&bitt

E. Wight and

S.

and N. Thomson,

Dornic.

197.5. ‘Imagery

eda.. Attention

and

performance.

Pre.\s. Janswn.

W.H..

the image. Janssen.

W.H..

Journal Kirk.

1976a. Selective Acta

1976b.

Selective

of Experimental

R.E..

1968.

interference

Paychologica

interference

Psychology

Experimental

in pared

asboclate

and free recall

learning:

messing

up

40. 35-48. during

the

rrtrleval

of

visual

images.

Quarterly

28, 535- 539.

design:

procedures

for

the

behavloural

sciences.

Belmont,

CA:

Brooks/Cole. Paivio.

A.. 1971. Imagery

Richardson.

J.T..

memory. Richardson,

197X.

Quarterly J.T..

and verbal Mental

Journal

Toglia.

M.P. and

Tulving.

E. and

V. Colotla.

Warren.

M.W..

1977. The effects

recall. Waugh.

Memory N.C‘. and

1970. Free

the

recall

Holt.

distinction

Psychology

and human

1978. Handbook

and Cognition D. Norman.

imagery

New York:

and

of Experimental

1980. Mental W. Battig.

processes.

imagery

of trilingual

of recall-concurrent

and Wmston. primary

and

secondary

30. 47 l-485.

memory.

of semantic

Rinehart betureen

London:

MacMillan.

Hard

norms.

lists.

Cognitive

vi.\ual-motor

Hillhdale.

NJ:

Psychology

distraction

Erlhaum. I, 86-89.

on picture

and uord

5. 362-370. 1965. Primary

memory.

Psychologxal

Review

72. X9%104.