We were interested in examining patterns of short-term information recall. We
used the Brown-Peterson distractor technique to investigate the effects of
stimuli type and delay interval on recall for 17 Ss. Each S was tested under 4
conditions, combined of word triads or nonsense syllables triads, with a short
(10-sec) or long (45-Sec) delay interval. S read aloud the visually presented
stimulus items, and aurally recalled them after the delay interval, in which S
was engaged in counting backwards in threes from a presented 3-digit number.
Measures were taken only for recall proportion. Results suggest a significant
difference in recall between words and nonsense syllables, with words
significantly better recalled. For the delay interval, results show no
significant effect, and thus differ from those obtained in previous research.
This discrepancy is discussed in terms of technical differences in procedure. No
other effect or interaction approached significance. Short-term Recall As a
function of Type of Stimulus and Length of Delay Interval Short-term memory (STM)
has been vastly studied and tested. One of the popular testing methods for STM
has been the short-term recall, in which S is shortly presented with a single or
multiple items, later to be recalled. Various researchers have focused their
studies on different aspects, while attempting to identify those factors that
most strongly influence short-term recall. A short-term memory model based upon
a limited capacity to process information suggests that the recall of verbal
material can be effected by the activity which consumes the retention interval,
referred to as the interpolated activity. Diverse studies examine the
significance of elements involved in the interpolated task. In general,
researchers have attempted to prevent Ss from rehearsing, i.e., processing
exposed stimuli by keeping the material within the short-term store through the
use of rehearsal-preventing interpolated tasks. The most famous of these has
been suggested in the Brown-Peterson technique (Peterson & Peterson, 1959)
in the form of backwards counting. In the original Peterson studies (1959), Ss
attempted to retain aurally presented consonants trigrams while counting
backwards by three or four from a three-digit number. This interpolated activity
was continued for some predetermined retention interval, immediately after which
Ss were asked to recall the originally presented consonants. Using this
technique, the Petersons demonstrated a very rapid decline in recall. The
probability of recall decreased exponentially with duration of interpolated
activity. Murdock (1960) investigated the effect of the stimulus type and the
effect of varying the rate of interpolated activity. Similarly to the Petersons
(1959) he found that in all cases forgetting, whether measured by accuracy or
latency, increased with the duration of the interpolated activity. In addition,
Murdock suggested little difference between the retention of three consonants
and three words; consonant syllables and word triads were equally well recalled.
Murdock (Tell, 1971) has shown that short-term recall is effected by whether the
presentation is visual or auditory. According to Neisser (Tell, 1971) there is
an auditory-storage system which results from auditory input and can function as
a source of information in short-term recall. This temporary storage system is
referred to as echoic memory. ⌠Echoic memory is passive, continuous,
composed of sounds, and decays rapidly■ (Tell, p. 150). However, auditory
input may also function as auditory noise. Voiced recall, vocalized irrelevant
interpolated activity, or certain types of presentation conditions can mask,
erase, or overwrite information available in the echoic memory store. This
assumption is especially important when considering the interpolated activity.
Tell (1971) suggested that a verbal interpolated task, in addition to its role
as a rehearsal-prevention activity, would also produce auditory feedback, which
masks information from echoic memory. Tell and Ferguson (1974) further explored
this issue of vocalization by examining the influences of active and passive
vocalization on short-term recall. As distinguished by Crowder (Tell &
Ferguson, 1974), active vocalization refers to presentation conditions where the
to-be-remembered stimulus items are voiced aloud by S as they are visually
presented. Under passive vocalization conditions, S listens to E read each
stimulus item as it is visually presented. Tell & Ferguson suggested that
active and passive vocalization differ mainly at the longer retention intervals,
with recall much higher under the passive vocalization condition. This supported
the idea that active vocalization could interfere with effective rehearsal or
encoding strategies. Another variable manipulated in search of significant
effect on recall is whether interpolated tasks were rewarded or not. Soucar,
Walk, and Covert (1971) suggested that retention of syllables is reduced under
rewarded conditions. However, productivity and accuracy of the actual
interpolated tasks was unchanged by reward. The present experiment is designed
to examine short-term recall as a function of stimulus type and length of delay
interval. We hypothesize that both variables will be found to be significant.
Specifically, we predict that: 1) recall proportion will be higher for words in
compare to nonsense syllables; 2) recall proportion will decrease with the
increase of delay intervals. Method Participants Seventeen Hunter undergraduate
psychology students served as Ss; twelve were female. Their age range was 18-32.
They were demanded to participate in the experiment as part of their
Experimental Psychology course requirement. Apparatus The group of participants
was assigned to pairs, who conducted the experiment in small cubicles, so that
each pair worked independently of the other pairs. However, cubicles were not
soundproof. Each of the participants served both as S and as E, in alternation
with his/her partner. Two sets of stimuli were presented: nonsense syllables and
words. The class of participants constructed both sets of stimuli. Each E
individually selected twenty-four nonsense syllables and another twenty-four
words out of two separated class-constructed lists. A nonsense syllable was
defined as a vowel surrounded by two consonants, and was selected in such a way
as to minimize association value and avoid acronyms or similarity to any other
selected syllables. The words were 3-5 letters long, mostly nouns, and withdrawn
from different categories. The stimuli were presented on white index cards; each
12.5 X 7.5 cm in size. Each set of stimuli (words or nonsense syllables)
constituted of eight cards. Each stimulus card had either three nonsense
syllables or three words hand written by pen (black or blue), and located at the
center of the card. Size of letters was not precisely controlled, but was
considered appropriate if enabled the S to see it from about two feet away from
card. On the opposite side of the stimulus card was a randomly selected
three-digit number, similarly written and located. Either standard hand watches
or digital stopwatches measured 45 or 10-sec delay intervals. Procedure All
sixteen subjects received a 16-trial sequence, involving the presentation of 16
word or nonsense syllables triads. Each trial consisted of a short visual
presentation of the stimuli, manually performed by E, who set opposite to S. The
active vocalization condition required Ss to read the triads aloud while they
were shown. Using the Brown-Peterson distracter technique (Peterson &
Peterson, 1959), Ss attempted to retain item triads while performing an
interpolated task. The interpolated task involved counting backwards in threes
from a presented three-digit numeral. Two lengths of interval delays were used:
10 or 45 sec. Once the interval delay was over, S would immediately stop
interpolated activity, and orally recall each item, regardless of its order of
position within the triad. E recorded retention scores, which ranged from 0 to
3, with 1 point given for each correctly recalled item. Performance on the
interpolated activity was not recorded. Order of stimuli presentations were
constructed in such a way that no type of stimulus followed itself. Stimuli were
presented in the following order: 1) four words-short interval; 2) four nonsense
syllables √ long delay; 3) four words √ long delay; 4) four nonsense
syllables √ short delay. Results The data of each S were scored in terms
of the correct number of items recalled, regardless of the items▓
positions within the triad. An overall analysis of variance was performed on the
recall scores. Since one group of Ss was tested under the entire four conditions
(repeated measures), a within-subjects ANOVA was computed for a two-factor
design. Stimuli type served as factor A, while delay interval served as factor
B. The only significant effect found was the type of stimulus presented. As seen
in figure 1, recall was significantly better for words than for nonsense
syllables under both retention intervals {F (1,16)=30.96, P* .05}. Tests of
simple main effects for type of stimuli again showed recall of words (9.3)
superior to nonsense syllables (7.02). No significant difference was found in
main effects for length of retention interval; recall did not decline with the
increase in delay interval {F (1,16)=0.005, P* .05}. No significant interaction
(one that would indicate differences not explainable by main effects) was found
between factors A & B, i.e., between stimulus type and retention interval {F
(1,16)=0.76, P*.05}. In summary, only type of stimuli was found to have a
significant effect on recall performance, with a superiority of words over
nonsense syllables. Discussion The above-described results lend support to our
hypothesis that words are better recalled than nonsense syllables. As predicted,
this effect of type of stimuli was found to be significant. However, for the
effect of length of delay interval, our results significantly differ from those
obtained by previous studies. Peterson & Peterson (1959), Murdock (1960),
and Tell (1971) have all shown a decrease in the proportion of recalled items as
a function of increased retention intervals. In all of these cases, forgetting
increased with the duration of the interpolated activity. Our results suggested
no significance to the delay interval effect. This discrepancy might be
explained in terms of technical differences in procedures.

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