Noise effects on rehearsal rate in short term serial order memory

Three experiments are reported which were designed to test the hypothesis that the rate of rehearsal during noise is slower than that under quiet conditions. The first experiment measured directly the rate of articulation while subjects either read or rehearsed a set of five consonants. It was shown that while the rate of articulation when reading aloud did not differ under the two noise levels [65 dB(C) and 85 dB(C)], rate of articulation during overt rehearsal in loud noise was significantly slower than under quiet conditions. In Experiment II a similar effect was demonstrated where words were required to be read or rehearsed; here it was shown that the greatest impairment due to noise was on the rate of rehearsal of words of long spoken length.

The third experiment showed that loud noise impaired recall performance more markedly for a set of words of long spoken length presented early on in the sequence than for a set of shorter words, even though both sets were equal in the number of syllables and phonemes they contained.

It was concluded that in verbal memory tasks where rote rehearsal of the to-be-remembered material is the predominant strategy for enhancing trace duration, noise may affect memory performance by slowing down the rehearsal rate.     

Maximizing noise energy for noise-masking studies

Noise-masking experiments are widely used to investigate visual functions. To be useful, noise generally needs to be strong enough to noticeably impair performance, but under some conditions, noise does not impair performance even when its contrast approaches the maximal displayable limit of 100 %. To extend the usefulness of noise-masking paradigms over a wider range of conditions, the present study developed a noise with great masking strength. There are two typical ways of increasing masking strength without exceeding the limited contrast range: use binary noise instead of Gaussian noise or filter out frequencies that are not relevant to the task (i.e., which can be removed without affecting performance). The present study combined these two approaches to further increase masking strength. We show that binarizing the noise after the filtering process substantially increases the energy at frequencies within the pass-band of the filter given equated total contrast ranges. A validation experiment showed that similar performances were obtained using binarized-filtered noise and filtered noise (given equated noise energy at the frequencies within the pass-band) suggesting that the binarization operation, which substantially reduced the contrast range, had no significant impact on performance. We conclude that binarized-filtered noise (and more generally, truncated-filtered noise) can substantially increase the energy of the noise at frequencies within the pass-band. Thus, given a limited contrast range, binarized-filtered noise can display higher energy levels than Gaussian noise and thereby widen the range of conditions over which noise-masking paradigms can be useful.     

Tinnitus and short-term serial recall in stable versus intermittent masking conditions

The relation between tinnitus and short-term memory performance in varying background sounds is not well understood. In the present study a sample of 18 persons with tinnitus completed a serial recall test in three conditions, silence, masking and intermittent masking. The performance of a matched control group without tinnitus was also investigated. Based on the literature on the "irrelevant sound effect" we expected that the tinnitus group would perform worse during intermittent masking and that they would score lower overall compared to the control group. Results revealed no statistically significant differences between the groups, nor any group interaction within sound conditions for the serial recall test. Groups did however differ regarding subjective measures of concentration problems, anxiety and depression. Results are discussed in relation to thought suppression and distraction from tinnitus.     

Recognition memory for prose items in noise

Using a probe-recognition technique the signal detection theory parameters d' and Beta were estimated for three types of probe (common surnames, uncommon surnames and synonyms) for material contained in a prose passage. Subjects were presented with the prose passage either in the presence of noise (85dBA) or in quiet (60dBA). In two experiments the effects of noise on auditory and visual presentation of the passage were studied. In both cases the recognition test took place in quiet. Noise decreased values of Beta for rare names and increased Beta for common names in both auditory and visual versions of the task. Noise influenced d' values in the auditory version only, with d' increasing for common names in loud noise. The results support the view that noise influences performance by disturbing the pigeon-holing mechanism with the qualification that when material may not be recapitulated (as in the auditory presentation in the present study) greater attention may be allocated to easily recognizable material. The findings give little support to theories of noiseinduced deficits in performance based on the masking of inner speech.     

Maintenance of item and order information in verbal working memory

Although verbal recall of item and order information is well-researched in short-term memory paradigms, there is relatively little research concerning item and order recall from working memory. The following study examined whether manipulating the opportunity for attentional refreshing and articulatory rehearsal in a complex span task differently affected the recall of item- and order-specific information of the memoranda. Five experiments varied the opportunity for articulatory rehearsal and attentional refreshing in a complex span task, but the type of recall was manipulated between experiments (item and order, order only, and item only recall). The results showed that impairing attentional refreshing and articulatory rehearsal similarly affected recall regardless of whether the scoring procedure (Experiments 1 and 4) or recall requirements (Experiments 2, 3, and 5) reflected item- or order-specific recall. This implies that both mechanisms sustain the maintenance of item and order information, and suggests that the common cumulative functioning of these two mechanisms to maintain items could be at the root of order maintenance.     

Verbal rehearsal and selective attention in children with learning disabilities: A developmental lag

To investigate the development of verbal rehearsal strategies and selective attention in learning disabled children, Hagen's Central-Incidental task was administered to younger learning disabled (M CA = 8.68 years) and normal (M CA = 8.62 years) boys in Experiment 1 and to intermediate (M CA = 10.18 years) and older (M CA = 13.48 years) learning disabled boys in Experiment 2. Also, in Experiment 2, an experimentally induced verbal rehearsal condition was included to determine its effects on serial recall and selective attention performance. In Experiment 1, the serial postion curve of the normals revealed both a primacy and a recency effect, whereas that of the learning disabled revealed a recency effect only. In Experiment 2, both the intermediate and the older learning disabled exhibited both primacy and recency effects under both standard and rehearsal conditions. A developmental analysis of central recall for the three learning disabled groups revealed constant age-related increases in overall central recall and in primacy recall. That the normals recalled more central, but not more incidental, information than the learning disabled in Experiment 1 suggests that the learning disabled are deficient in selective attention. Correlational findings suggest that the selective attention of the learning disabled improves with age. The results were interpreted as support for the hypothesis of a developmental lag in the learning disabled population.     

Right-ear advantage and delayed recall

Two studies were performed using monaural presentation of verbal material to test for a right-ear advantage (REA) in recall. It was hypothesized that a delayed recall task and examination of the serial position curve would be a more sensitive test for ear asymmetries than those used in previous studies. In Experiment 1, 30 right-handed male subjects were given lists of words to recall, presented to either the left or right ear, with language chatter, baroque music, or no stimulus concurrently presented to the opposite ear. Both immediate and delayed recall were assessed. The results indicated that the strongest REAs appeared in delayed recall. Moreover, the REAs occurred regardless of the stimulus conditions co-occurring in the other ear. Experiment 2 was done to test whether the REAs in the delayed recall were due to rehearsal biases. Twenty-four right-handed male subjects recalled lists of words with standard instructions and instructions to recall in the reverse order of input (limiting rehearsal). The results indicated that the backward instructions limited and controlled rehearsal and, hence, input to long-term storage; the REAs occurred in delayed recall under all instructional conditions.     

Listening to discourse in distracting settings: the effects of aging

Younger and older adults listened to discourse in quiet and in conversational noise, before answering questions concerning the material. Some questions required listeners to recall specific details; others were of a more integrative nature. When the listening situation was adjusted for individual differences in hearing, younger and older adults were equally adept at remembering the gist of the passages in both quiet and in two levels of noise. The two age groups also did not differ with respect to memory for specific details when listening in quiet or in a moderate level of noise, even when required to perform a concurrent task. Only at the loudest noise level did younger adults tend to recall more detail than older adults. However, when no adjustments were made to compensate for the poorer hearing of older adults (all participants tested under identical listening conditions), older adults could not recall as much detail as younger adults, either in quiet or in noise. The results indicate that the speech-comprehension difficulties of older adults primarily reflect declines in hearing rather than in cognitive ability.     

Examining the relationship between free recall and immediate serial recall: the effect of concurrent task performance

In 3 experiments, participants saw lists of 16 words for free recall with or without a 6-digit immediate serial recall (ISR) task after each word. Free recall was performed under standard visual silent and spoken-aloud conditions (Experiment 1), overt rehearsal conditions (Experiment 2), and fixed rehearsal conditions (Experiment 3). The authors found that in each experiment, there was no effect of ISR on the magnitude of the recency effect, but interleaved ISR disrupted free recall of those words that would otherwise be rehearsed. The authors conclude that ISR and recency cannot both be outputs from a unitary limited-capacity short-term memory store and discuss the possibility that the process of rehearsal may be common to both tasks.     

Rehearsal strategy as a function of recall expectation

The subjects were divided into three groups with respect to their expectations concerning a recall task given after the final trial of the usual STM distractor procedure. Group 1 were told only that they would have to recall during each trial's recall interval, thus did not expect to have to recall again. Group 2 were told that they would have to recall all the words presented in the experiment at the end of the last trial, in addition to the trial-by-trial recall. Group 3 were told only that they would have to recall after all words had been presented and they sat passively through the presentation trials. In addition to their recall expectations, half of the subjects in each group received a 2-s presentation and half received a 5-s presentation interval. It was found that the length of the presentation interval had an effect on the number of words recalled at the end of all trials, but recall expectancy did not. However, expectancy did determine the rehearsal strategies of subjects and hence the serial positions from which items were recalled.     

Sources of auditory masking in infants: distraction effects.

Previous work has demonstrated that infants' thresholds for a pure tone are elevated by a masker more than would be predicted from their critical bandwidths. The present studies explored the nature of this additional masking. In Experiment 1, detection thresholds of 6-month-old infants and of adults for a 1-kHz tone were estimated under three conditions: in quiet, in the presence of a 4- to 10-kHz bandpass noise at 40 dB SPL, and in the presence of the same noise at 50 dB SPL. The noise was gated on at the beginning of each trial. Adult thresholds were the same in all three conditions, indicating that little or no sensory masking took place in the presence of the noise. Infant thresholds were about 10 dB higher in the presence of the noise. We term this effect distraction masking. In Experiment 2, the effect of gating the noise on at trial onset was examined. Thresholds for the same tone were estimated in quiet and in the presence of the band-pass noise at 40 dB SPL, but the noise was presented continuously during the session. Under these conditions, distraction masking was still observed for infants. These findings suggest that a masker can have nonsensory effects on infants' performance in a psychoacoustic task.     

The Relationship Between Spirituality and Eysenck's Personality Dimensions: A Replication Among English Adults

A serial recall task was used to compare performance of 15 normal and 15 learning disabled elementary school children matched on CA, IQ, and sex with two and three dimensional representations of nonverbal eight-point shapes. Two a priori assumptions were not supported: (a) no differences in recall were found between groups and (b) no differences in recall were found for either group using two or three dimensional stimuli. Three imensional stimuli did facilitate visual rehearsal at the primacy position for both groups. Learning disabled children's performance was consistent with the mediation deficiency hypothesis found with normal children.     

Shorter articles and notes noise and the shifting of attention

An experiment was carried out to test the hypothesis that performance on a task which involves a shift of attention between spatially separated sources would be lower under noise conditions than one which involved no such shift. The results indicated that the hypothesis was not proved; rather they showed that the subject's performance on the shift of attention task was better under noise than under quiet. An attempt is made to put forward possible reasons for this occurrence.     

Brain injury and movement recall: Preselection, active-passive and interference effects

Stroke patients with unilateral lesions were compared with age-controls and students on their ability to reproduce a terminal location established kinesthetically by a previous movement. Conditions for the criterion movement differed over active/passive and preselected/constrained (experiment 1) and whether the retention interval between the criterion and recall movements involved mental rehearsal of the criterion movement or yes/no responding to a mental arithmetic task (experiment 2). Whereas students showed more accurate recall with little effect of criterion movement condition, patient groups showed a preselection effect, but only with active movements. A preferred hand advantage observed for the patient controls did not occur with stroke patients, and prevention of mental rehearsal during the retention interval disrupted recall more for the stroke patients. These findings are interpreted in terms of hemisphere-specific coding strategies whose relative use depends on the attentional demands of the task.     

Sources of auditory masking in infants: Distraction effects

Previous work has demonstrated that infants’ thresholds for a pure tone are elevated by a masker more than would be predicted from their critical bandwidths. The present studies explored the nature of this additional masking. In Experiment 1, detection thresholds of 6-month-old infants and of adults for a 1-kHz tone were estimated under three conditions: in quiet, in the presence of a 4- to 10-kHz bandpa] noise at 40 dB SPL, and in the presence of the same noise at 50 dB SPL. The noise was gated on at the beginning of each trial. Adult thresholds were the same in all three conditions, indicating that little or no sensory masking took place in the presence of the noise. Infant thresholds were about 10 dB higher in the presence of the noise. We term this effectdistraction masking. In Experiment 2, the effect of gating the noise on at trial onset was examined. Thresholds for the same tone were estimated in quiet and in the presence of the bandpass noise at 40 dB SPL, but the noise was presented continuously during the session. Under these conditions, distraction masking was still observed for infants. These findings suggest that a masker can have nonsensory effects on infants’ performance in a psychoacoustic task.     

Effects of jet engine noise and performance feedback on perceived workload in a monitoring task

This study examined the effects of exposure to intermittent jet aircraft noise (70 dBA or 95 dBA maximum intensity) and knowledge of results concerning signal detections (hit-KR) on performance efficiency and perceived workload in a 40-min visual vigilance task. The noise featured a Doppler-like quality in which planes seemed to approach from the monitor's left and recede to the right. Perceptual sensitivity (d') was poorer in the context of noise than in quiet but only in the presence of hit-KR. The lack of noise-related performance differences in the absence of hit-KR most likely reflected a "floor effect" rather than some special relation between noise and feedback. When compared to subjects performing in quiet, those who operated in noise were less able to profit from hit-KR, a result that may reflect the effects of noise on information processing. In addition to its negative effects on signal detectability, noise elevated the perceived workload, as measured by the NASA-TLX. This effect was robust; it was independent of the presence of hit-KR, even though hit-KR generally lowered the overall level of perceived workload. The results provide the initial experimental demonstration that perceived workload is a sensitive measure of the effects of aircraft noise in monitoring tasks.     

An “across-the-board” modality effect in immediate serial recall

A serial recall experiment comparing visual and auditory presentation is reported which demonstrates that, under certain conditions, there is an auditory advantage in the pre-recency (1-6) as well as the recency (7-8) serial positions. Presentation modality was combined factorially with five levels of a concurrent writing task, which had to be completed for each to-be-remembered digit during presentation: NC, no concurrent task; XX, writing two crosses; DX, writing each digit followed by a cross; XD, the converse of DX; and DD, writing each digit twice. When presentation was visual, there was a monotonic (non-decreasing) trend in the recall errors going from NC to DD (in above order) for both the pre-recency and recency positions on average. With an auditory presentation, however, the trend was more gradual, though still monotonic. For the pre-recency items, an auditory advantage was obtained with conditions XX, XD and DD, but not for NC and DX. Additionally, with an auditory presentation, there was no evidence of a difference between NC and XX, nor between DX and XD. It is argued that both pre-categorical acoustic storage and residual activation effects, engendered in a logogen system (Morton, 1970) by the repetition “structure” of the concurrent tasks, helped to determine the attentional capacity available for secondary (elaborative) rehearsal and, in turn, set the levels of recall.     

Flanker recall and the flanker validity effect may reflect different attentional processes

High flanker recall in the correlated flanker task suggests a failure of selective attention. We used a dissociation approach to examine the role of attentional processing of the flankers’ identities in the flanker validity effect (FVE). In three experiments, flanker recall decreased as flanker duration decreased, but the FVE was not affected by flanker duration. Masking also produced a dissociation, in that masking decreased flanker recall but the FVE was not affected. Examination of on-line flanker identification suggested that flanker recall was an adequate measure of attentional processing of the flankers’ identities on most trials. The results suggest that attentional processing of the flankers’ identities is not related to the magnitude of the FVE and is not necessary for it to obtain. Because there is a failure of selective attention, the dissociations suggest that flanker recall and the FVE may reflect different attentional processes.     

Flanker recall and the flanker validity effect may reflect different attentional processes.

High flanker recall in the correlated flanker task suggests a failure of selective attention. We used a dissociation approach to examine the role of attentional processing of the flankers' identities in the flanker validity effect (FVE). In three experiments, flanker recall decreased as flanker duration decreased, but the FVE was not affected by flanker duration. Masking also produced a dissociation, in that masking decreased flanker recall but the FVE was not affected. Examination of on-line flanker identification suggested that flanker recall was an adequate measure of attentional processing of the flankers' identities on most trials. The results suggest that attentional processing of the flankers' identities is not related to the magnitude of the FVE and is not necessary for it to obtain. Because there is a failure of selective attention, the dissociations suggest that flanker recall and the FVE may reflect different attentional processes.     

Memory strategies in children with learning disabilities

Memory strategies were examined among children, 7–13 years old, with diagnosed learning disabilities, in order to investigate whether they perform in appropriately active and efficient ways. The children were grouped at two age levels and administered tasks of serial recall and free recall. A strategy-training session was conducted on the second task. On the serial recall, neither age group showed evidence of rehearsal, in contrast to previous studies. On the free recall task, the younger children's performance was consistent with the mediation deficiency hypothesis, while the older children improved in sorting, clustering, and recall following training; i.e., they showed a typical production deficiency. There was support for considering this sample of learning disabled children as inactive learners, with potential developmental change. Serial recall improved with age, and the older children's production deficiences in free recall appeared to be ameliorated with training in organizational strategies.