The effects of load variability in short-term memory task

Six groups of Ss viewed briefly exposed arrays of letters, half designated high-valued and half low-valued. Immediately after each exposure Ss wrote down as many of the stimuli as they could remember. For three groups, the number of letters in each exposure was constant from trial to trial; for the remaining three groups, the number of letters in each exposure varied from trial to trial. This tested the hypothesis that load variability influences the development of an efficient response strategy which, in turn, affects the processing of information stored in short-term memory. The data supported this hypothesis. Performance was superior under the constant load condition due to the ability of these Ss to correctly report both high- and low-valued letters. Poor performance was observed under the variable load condition because of a decrease in the number of low valued letters correctly reported.     

False memory in a short-term memory task

The Deese/Roediger-McDermott (DRM; Roediger & McDermott, 1995) paradigm reliably elicits false memories for critical nonpresented words in recognition tasks. The present studies used a Sternberg (1966) task with DRM lists to determine whether false memories occur in short-term memory tasks and to assess the contribution of latency data in the measurement of false memories. Subjects studied three, five, or seven items from DRM lists and responded to a single probe (studied or nonstudied). In both experiments, critical lures were falsely recognized more often than nonpresented weak associates. Latency data indicated that correct rejections of critical lures were slower than correct rejections of weakly related items at all set sizes. False alarms to critical lures were slower than hits to list items. Latency data can distinguish veridical and false memories in a short-term memory task. Results are discussed in terms of activation-monitoring models of false memory.     

Age differences in visual and kinesthetic short-term memory

30 elderly subjects were matched with 30 young subjects and tested on a kinesthetic short-term memory task which required the replication of criterion moves after a variable retention interval under conditions of either rest, differing interpolated movement tasks, or mental activity. A visual control condition was used. Differing interference and temporal decrements were observed. Both old and young subjects differed significantly between sighted and blindfold conditions; however, there was no difference between the performance of the old and the young in the blindfold (kinesthetic) condition. These findings were discussed with respect to practical implications for the retraining of old subjects on certain motor tasks.     

Pictorial and verbal encoding in a short-term memory task

The present research attempted to manipulate the encoding modality, pictorial or verbal, of schematic faces with well-learned names by manipulating S’s expectations of the way the material was to be used. On every trial, a single name or face was presented, followed by another one; the S was asked to respond “same” if the stimuli had the same name, and “different” otherwise. The majority of second stimuli of any session was either names or faces. It was hypothesized that if S had encoded the first stimulus in the modality of the second, his judgment would be faster than if he had not appropriately encoded the first stimulus. Significantly slower reaction times were obtained to stimulus pairs where the second stimulus modality was infrequent. Further evidence that encoding of the first stimulus was in the frequent second stimulus modality comes from the finding that “different” responses were shorter when the stimuli differed on more than one attribute in the encoding (second stimulus) modality, regardless of the modality of the stimuli. Thus, evidence is presented that not only can verbal material be pictorially encoded (and vice versa), but that whether either verbal or pictorial material is verbally or pictorially encoded depends on S’s anticipation of what he is to do with the material.     

Habituation to irrelevant speech: effects on a visual short-term memory task

The Baddeley and Hitch (1974) formulation of short-term or working memory embodied a phonological store within the articulatory loop component of the model. Later formulations specifically postulated an acoustic filter that endowed only speech-like stimuli with obligatory access to this phonological store. This paper presents evidence that this phonological store may have two filters, one of which is subject to habituation and can therefore attenuate the entry of irrelevant speech, thus undermining the obligatory access assumption of the model. An experiment is reported in which subjects were presented with a habituation period comprising 20 min of irrelevant speech--speech to be ignored by the subject--before a test phase in which a visually presented serial recall task with concurrent irrelevant speech was performed. The effect of irrelevant speech, which impairs performance on the primary task when there is no habituation phase, is reduced markedly in those conditions where the speech used in the habituation phase is the same as that used in the test phase, if the irrelevant speech is in a language different from that presented during the subsequent trials or if the habituator is a hummed version of the irrelevant speech passage. When a nonspeech sound (pink noise) is used in the habituation phase, a large irrelevant speech effect is found in the test phase. Morris, Quayle, and Jones (1989) found that humming did not produce an irrelevant speech effect, which suggests that the first filter is permeable to humming but that the second filter is not.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prospective memory in children: the effects of age and task interruption

Prospective memory (PM), remembering to carry out a task in the future, is highly relevant to children's everyday functioning, yet relatively little is known about it. For these reasons the effects of age and task interruption on PM were studied in 3 experiments. Children aged 4, 5, and 7 years were asked to name pictures in stacks of cards (the ongoing task) and to remember to do something when they saw a target picture (the PM task). Significant age differences were identified, but age explained only a small amount of variance. As predicted, children in the no-interruption condition performed significantly better than those who had to interrupt the ongoing activity in order to carry out the PM task. An additional finding was that no relation was detected between performance on prospective and retrospective memory tasks. Taken together, these findings provide support for current models of PM and identify ways to assist children's PM.     

Redundancy effects in short-term memory

Five experiments are reported whose purpose was to demonstrate that short-term memory is improved by redundancy within the material. In Experiment I “tune” containing two, three, four and five tones of differing frequencies had to be coded into digits 1-5, to indicate the order of the pitches in a tune. Performance on stimuli containing correlated amplitude and duration were compared with the uni-dimensional condition. Experiment II repeated I, but required intensity to be coded. Experiment III required pitch coding under three conditions including that when amplitude and frequency were uncorrelated, and compared the performance of musically trained sunjects with nonmusicians. Experiment IV repeated III, but subjects were informed of the relation between dimensions. Experiment V involved “shadowing” the tunes by whistling simultaneously with the stimulus.

It was concluded (a) that intercorrelation improves, but zero correlation impairs short-term memory; (b) that knowledge of the relation between dimensions improves performance in the correlated condition, but does not prevent impairment under zero correlation; and (c) the performance of musically trained subjects exceeds that of controls and is unaffected by the presence of a correlated or uncorrelated dimension.     

Interference effects in short-term memory

Abstract.— Two experiments exploring the modality relation between memory task and interference task are reported. With visual and verbal tasks, variations in modality relation did not influence the total amount recalled. The usual serial position effect was observed when memory and interference task were of different modalities. The amount of recall was found to be a function of the memory strategies used by the subjects, 'active' strategies producing highest recall.     

Environmental context-dependent recognition memory using a short-term memory task for input

Although many studies have demonstrated that recall is better when tested in the learning environmental context (EC) than in a new EC, almost all of the studies have failed to find EC-dependent memory when recognition was used to measure memory. Evidence of EC-dependent recognition, however, was found in the three experiments of the present study, in which an incidental short-term memory task was used for input of learned material. The results suggest that type of processing during input is a predictor of context-dependent recognition; material studied for a long-term memory test is not susceptible to background context effects, whereas material merely maintained for a short-term memory test is more apt to lead to EC-dependent recognition.     

Serial-position effects in motor short-term memory

This study examined the effect of the length of a series of movements on the recall of those movements. Subjects (n = 45) were randomly assigned to one of three experimental groups with each group recalling either three, six, or nine movements on a linear-slide apparatus. The subjects, while blindfolded, were presented with each movement by actively moving to a stop. Recall occurred 5 sec after the last movement to a stop on a trial. All subjects were given nine trials, each containing a different series of to-be-recalled movements. Results indicated that absolute error of recall of the three movements increased in a linear fashion. However, for six and nine movements, a bowing effect of the recall curve was noted following the fifth position. A primacy effect was more evident than was a recency effect. Accuracy of recall was a function of list length up to six movements, after which accuracy was not further impaired.     

Changes of pupil size and rehearsal strategies in a short-term memory task

Twelve subjects learned lists consisting of 3 groups of 4 items each drawn from vocabularies of digits, colour names or boys' names. There were two conditions of recall, total or partial, and two retention intervals, 3 and 7 sec. A view of the function of rehearsal suggests that rehearsal for total recall should be more intense than for partial recall, but only with a brief retention interval. Measurements of pupillary diameter confirm this prediction. Conditions under which pupillary measurements can serve to test theories of psychological processes are discussed.     

The effects of auditory and visual distractors on children's performance in a short-term memory task

Five- and 8-year-old children's performance in a short-term memory task was assessed under two auditory and two visual distraction conditions, as well as with no extraneous stimuli present. Performance under distraction was found to be inferior to that under nondistraction, but the degree of difference was roughly the same at ages 5 and 8, indicating little developmental change in the effects of distraction over this age range. Other findings included differences in the effectiveness of the distractors used and evidence that the children adapted somewhat to the influence of extraneous stimulation.     

Decay and interference effects in motor short-term memory

Trace decay and interference effects in motor short-term memory were investigated by contrasting the predictions of two recent models (Pepper and Herman 1970; Laabs 1973) in regard to these two variables. Laabs' prediction that forgetting in motor short-term memory is indexed by greater variability of reproduction was supported in that movement reproduction after a 20 sec retention interval, either filled or unfilled, produced greater variable error. Further, his model was again supported in that analysis of constant error over five movement extents indicated interference effects through formation of an adaptation level which caused short movements to be overshot and long movements to be undershot. Pepper and Herman's concept of spontaneous trace decay indexed by a negative shift in constant error was not supported as was their prediction that interpolated activity would alter the strength of the criterion trace through an assimilation process. Finally, some evidence was found supporting the view that a memory trace can be strengthened through proprioceptive feedback entering through an unattended channel.     

The effect of invalid task parameters on short-term motor memory

Two experiments tested the influence of information from an invalid movement parameter on short-term motor memory for a valid task parameter. Experiment 1 showed that invalid task distance information affected location retention. Experiment 2 showed that invalid task location information affected task distance retention. These findings strengthen the evidence that the codes important for short-term motor retention are affected by a variety of factors within the movement context.     

Temporal grouping effects in musical short-term memory

Recent theoretical accounts of verbal and visuo-spatial short-term memory (STM) have proposed the existence of domain-general mechanisms for the maintenance of serial order information. These accounts are based on the observation of similar behavioural effects across several modalities, such as temporal grouping effects. Across two experiments, the present study aimed at extending these findings, by exploring a STM modality that has received little interest so far, STM for musical information. Given its inherent rhythmic, temporal and serial organisation, the musical domain is of interest for investigating serial order STM processes such as temporal grouping. In Experiment 1, the data did not allow to determine the presence or the absence of temporal grouping effects. In Experiment 2, we observed that temporal grouping of tone sequences during encoding improves short-term recognition for serially presented probe tones. Furthermore, the serial position curves included micro-primacy and micro-recency effects, which are the hallmark characteristic of temporal grouping. Our results suggest that the encoding of serial order information in musical STM may be supported by temporal positional coding mechanisms similar to those reported in the verbal domain.     

The effects of attention-directing training on recognition memory task performance of three-year-old children

Thirty-eight 3-year-old children served as subjects in an investigation of recognition memory in which schematic faces differing only in the orientation of the eyes were employed as stimuli. A pretest was administered to all children, after which the two experimental groups received training in either attention to the distinctive feature of the training stimuli (also schematic faces) by means of a matching task, or in labeling the faces according to how they looked (sleepy, happy, sad, mad) and in using the labels to perform a matching task. After the training session all children were given a posttest on recognition memory of the faces. The verbally trained group obtained significantly higher scores on the posttest than either the feature or control groups. These results indicate that although the children were able to discriminate the faces, evidenced in their ease of performance on the training tasks, they were not able to use this knowledge unless given training in attaching labels to the stimuli, which enabled them to store the information for later use. Results are discussed in light of Gibson's (1969) theory of the developmental interrelations of cognitive processes.     

Age and redintegration in immediate memory and their relationship to task difficulty

It is commonly assumed that as short-term memory tasks become more difficult, a transient phonological trace that supports recall loses its fidelity. Recall can still be achieved through a process called redintegration, where long-term phonological or lexical knowledge is used to reconstruct the memory trace. In the present research, we explored age-related differences in the redintegration process by having older and younger participants study lists under different levels of task difficulty. As a means of examining the redintegration process, in Experiment 1, semantic similarity was manipulated, and in Experiment 2, phonological similarity was varied. The results show that similarity effects can be accurately predicted from knowledge of task difficulty with item scoring, but not with order scoring. The results support the redintegration perspective and indicate that although there may be differences in the absolute level of recall across age groups, the redintegration process is identical for younger and older participants.