Chewing gum and context‐dependent memory: The independent roles of chewing gum and mint flavour

Two experiments independently investigated the basis of the chewing gum induced context‐dependent memory effect. At learning and/or recall, participants either chewed flavourless gum (Experiment 1) or received mint‐flavoured strips (Experiment 2). No context‐dependent memory effect was found with either flavourless gum or mint‐flavoured strips, indicating that independently the contexts were insufficiently salient to induce the effect. This is found despite participants’ subjective ratings indicating a perceived change in state following administration of flavourless gum or mint‐flavoured strips. Additionally, some preliminary evidence for a non‐additive facilitative effect of receiving gum or flavour at either learning and/or recall is reported. The findings raise further concerns regarding the robustness of the previously reported context‐dependent memory effect with chewing gum.     

Chewing gum moderates the vigilance decrement

We examine the impact of chewing gum on a Bakan‐type vigilance task that requires the continual updating of short‐term order memory. Forty participants completed a 30‐min auditory Bakan‐task either with, or without, the requirement to chew gum. Self‐rated measures of mood were taken both pre‐ and post‐task. As expected, the vigilance task produced a time‐dependent performance decrement indexed via decreases in target detections and lengthened correct reaction times (RTs), and a reduction in post‐task self‐rated alertness scores. The declines in both performance and subjective alertness were attenuated in the chewing‐gum group. In particular, correct RTs were significantly shorter following the chewing of gum in the latter stages of the task. Additionally, the gradients of decline for target detection and incline for correct RTs were both attenuated for the chewing‐gum group. These findings are consistent with the data of Tucha and Simpson (2011), Appetite, 56, 299–301, who showed beneficial effects of chewing gum in the latter stages of a 30 min visual attention task, and extend their data to a task that necessitates the continuous updating of order memory. It is noteworthy that our data contradict the claim (Kozlov, Hughes, & Jones, 2012, Q. J. Exp. Psychology, 65, 501–513) that chewing gum negatively impacts short‐term memory task performance.     

Gummed-up memory: chewing gum impairs short-term recall

Several studies have suggested that short-term memory is generally improved by chewing gum. However, we report the first studies to show that chewing gum impairs short-term memory for both item order and item identity. Experiment 1 showed that chewing gum reduces serial recall of letter lists. Experiment 2 indicated that chewing does not simply disrupt vocal-articulatory planning required for order retention: Chewing equally impairs a matched task that required retention of list item identity. Experiment 3 demonstrated that manual tapping produces a similar pattern of impairment to that of chewing gum. These results clearly qualify the assertion that chewing gum improves short-term memory. They also pose a problem for short-term memory theories asserting that forgetting is based on domain-specific interference given that chewing does not interfere with verbal memory any more than tapping. It is suggested that tapping and chewing reduce the general capacity to process sequences.     

Gummed-up memory: Chewing gum impairs short-term recall

Several studies have suggested that short-term memory is generally improved by chewing gum. However, we report the first studies to show that chewing gum impairs short-term memory for both item order and item identity. Experiment 1 showed that chewing gum reduces serial recall of letter lists. Experiment 2 indicated that chewing does not simply disrupt vocal–articulatory planning required for order retention: Chewing equally impairs a matched task that required retention of list item identity. Experiment 3 demonstrated that manual tapping produces a similar pattern of impairment to that of chewing gum. These results clearly qualify the assertion that chewing gum improves short-term memory. They also pose a problem for short-term memory theories asserting that forgetting is based on domain-specific interference given that chewing does not interfere with verbal memory any more than tapping. It is suggested that tapping and chewing reduce the general capacity to process sequences.     

Chewing gum while studying: Effects on alertness and test performance

Recent research has demonstrated chewing gum can enhance various cognitive processes associated with learning, but most studies have used cognitive functioning tasks (e.g., selective attention and working memory) as outcomes. Across two experiments, we investigated effects of chewing gum on self‐reports of alertness and test performance following study of realistic educational materials. In Experiment 1 (n = 40), adult participants who chewed gum while studying a 20‐min physiology lesson outperformed a nonchewing condition on subsequent terminology and comprehension tests, but did not report higher levels of postlesson alertness as hypothesised. In Experiment 2 (n = 39), adult participants who chewed gum while studying a 9‐min lesson on a mental mathematics strategy outperformed a nonchewing condition on a subsequent problem‐solving test, whereas also reporting higher levels of postlesson alertness. The results provide initial support for chewing gum while studying realistic educational materials across a range of topics and study durations.     

Do tests facilitate decision‐making performance on a transfer task?

Testing can improve later recall of information. However, much less is known about the potential use of testing in promoting the transfer of learning. In this study, we investigated whether testing improves decision‐making performance on a transfer task in a sample of 98 university students using a between‐subjects design. After studying several statements about a fictional disease under different learning conditions (restudy, free recall, and multiple‐choice), participants were asked to recall this information and subsequently make medical decisions concerning the fictional disease (i.e., the transfer task). The present study found no advantage of testing conditions over restudy condition on the 30‐min delayed memory task. However, participants in the active retrieval practice (i.e., free recall) group performed significantly better on the transfer task over those in both restudy and multiple‐choice groups. These results suggest free‐recall tests promote the transfer of learning.     

Transposition asymmetry in immediate serial recall

When participants confuse the position of items in immediate serial recall, they tend to recall transposed items too early rather than too late. This asymmetry of transposition errors was observed in four experiments. It increased as a function of list length, but was independent of report order, output position, cueing condition, and recall mode. The transposition asymmetry is consistent with error patterns in free recall and in regular speech production where transpositions are usually forward‐looking. The asymmetry of transposition errors is discussed in terms of models of serial memory.     

Diagnosing criterion-level effects on memory: what aspects of memory are enhanced by repeated retrieval?

Previous research has shown that increasing the criterion level (i.e., the number of times an item must be correctly retrieved during practice) improves subsequent memory, but which specific components of memory does increased criterion level enhance? In two experiments, we examined the extent to which the criterion level affects associative memory, target memory, and cue memory. Participants studied Lithuanian-English word pairs via cued recall with restudy until items were correctly recalled one to five times. In Experiment 1, participants took one of four recall tests and one of three recognition tests after a 2-day delay. In Experiment 2, participants took only recognition tests after a 1-week delay. In both experiments, increasing the criterion level enhanced associative memory, as indicated by enhanced performance on forward and backward cued-recall tests and on tests of associative recognition. An increased criterion level also improved target memory, as indicated by enhanced free recall and recognition of targets, and improved cue memory, as indicated by enhanced free recall and recognition of cues.     

Reducing the Misinformation Effect Through Initial Testing: Take Two Tests and Recall Me in the Morning?

Initial retrieval of an event can reduce people's susceptibility to misinformation. We explored whether protective effects of initial testing could be obtained on final free recall and source‐monitoring tests. After studying six household scenes (e.g., a bathroom), participants attempted to recall items from the scenes zero, one, or two times. Immediately or after a 48‐hour delay, non‐presented items (e.g., soap and toothbrush) were exposed zero, one, or four times through a social contagion manipulation in which participants reviewed sets of recall tests ostensibly provided by other participants. A protective effect of testing emerged on a final free recall test following the delay and on a final source‐memory test regardless of delay. Taking two initial tests did not increase these protective effects. Determining whether initial testing will have protective (versus harmful) effects on memory has important practical implications for interviewing eyewitnesses. © 2015 The Authors. Applied Cognitive Psychology published by John Wiley & Sons, Ltd.     

Odour and Proustian memory: reduction of context‐dependent forgetting and multiple forms of memory

In Experiment 1, the reintroduction of the same ambient odour (lemon or lavender) improved performance four weeks later in both free recall and recognition of a word list. This was a cross‐over design that allowed direct comparison between congruent and incongruent odour conditions. A further comparison with an additional group showed that memory was not improved by the presence of a different odour. Experiment 2 investigated the effect of two odour cues (lemon and lavender) in the same cross‐over design using three learning and memory tests: (1) free recall of a word list; (2) problem solving; and (3) spatial learning. While recall of the word list and spatial learning were best when the same odour was present at both learning and test, there was no such context‐dependent effect for the problem‐solving task. However, the presence of the lavender odour at test improved performance in the problem‐solving task, irrespective of the odour present at the first exposure. Thus although lavender had some effect on problem solving, we saw context‐dependent retrieval only in free recall and spatial learning. We discuss the implications of this dissociation. Copyright © 2001 John Wiley & Sons, Ltd.     

Transposition asymmetry in immediate serial recall

When participants confuse the position of items in immediate serial recall, they tend to recall transposed items too early rather than too late. This asymmetry of transposition errors was observed in four experiments. It increased as a function of list length, but was independent of report order, output position, cueing condition, and recall mode. The transposition asymmetry is consistent with error patterns in free recall and in regular speech production where transpositions are usually forward-looking. The asymmetry of transposition errors is discussed in terms of models of serial memory.     

When people’s judgments of learning (JOLs) are extremely accurate at predicting subsequent recall: the “Displaced-JOL effect”

Judgments of learning (JOL) made after a delay more accurately predict subsequent recall than JOLs made immediately after learning. One explanation is that delayed JOLs involve retrieving information about the target item from secondary memory, whereas immediate JOLs involve retrieval from primary memory. One view of working memory claims that information in primary memory is displaced to secondary memory when attention is shifted to a secondary task. Thus, immediate JOLs might be as accurate as delayed JOLs if an intervening task displaces the target item from primary memory, requiring retrieval from secondary memory, prior to making the JOL. In four experiments, participants saw related word-pairs and made JOLs predicting later recall of the item. In Experiment 1, delayed JOLs were more accurate than JOLs made shortly after learning, regardless of whether a secondary task intervened between learning and JOL. In Experiments 2–4, the secondary task demands increased and JOLs made shortly after learning with an intervening task were just as accurate as delayed JOLs, and both were more accurate than immediate JOLs with no intervening task (Experiment 4). These results are consistent with a retrieval-based account of JOLs, and demonstrate that the “delayed-JOL effect” can be obtained without a long delay.     

Can intentional forgetting reduce false memory? Effects of list-level and item-level forgetting

This study examined whether false memory produced by the learning of lists of categorized and associative materials could be reduced by directed forgetting. The number of items within a list that participants were asked to remember or forget was manipulated, while the length of the list remained constant. Experiment 1a used categorized lists and Experiment 1b used associative lists; the participants performed immediate free recall and cued recall tests. For both the categorized and associative lists, the rate of false recall increased upon increasing the proportion of "forget" (F) words. After removing the immediate recall test, Experiment 2 found that intentionally forgetting part of the studied list reduced false memory, whereas forgetting the whole studied list did not. The results are discussed in terms of the list-level-vs.-item-level inhibition in semantic activation and the role of monitoring in reducing false memory.     

Is there a memory profit after repeated learning of subject‐performed actions? Comparing direct and long‐term memory performance level as a function of age

Schatz, T.R., Spranger, T. & Knopf, M. (2010). Is there a memory profit after repeated learning of subject‐performed actions? Comparing direct and long‐term memory performance level as a function of age. Scandinavian Journal of Psychology 51, 465–472. The present two studies investigated the possibility for improvement and maintenance of episodic memory in young and older adults. In a first study, the performance‐enhancing effect of two separate as well as combined learning devices, enactive encoding and repeated learning, was tested. With a time lag of one week, four different series of 30 action phrases were encoded either verbally or by enacting them symbolically. Memory was assessed in four immediate free recall tests. In a second study, the maintenance of the memory profit was tested in an unexpected fifth session half a year later. As expected, there was a steady improvement of memory performance as a function of repeated learning in study one. This holds true regardless of age. In addition, enactive encoding led to a better memory performance than verbal encoding in both age groups. Moreover, younger adults outperformed the elderly regardless of type of encoding. The combination of the two learning devices was not efficient enough to eliminate aging effects in episodic memory. However, memory flexibility is demonstrated also in the elderly. In the long‐term follow‐up, maintenance of learning and memory could be found in all participant groups.     

Social demand characteristics in children's and adults' eyewitness memory and suggestibility: the effect of different interviewers on free recall and recognition

Shortly after viewing a video of a theft, 5‐ and 7‐year‐old children and adults were interviewed with free recall and either misleading or unbiased‐leading questions. After a 2‐day delay, participants were interviewed with free recall and recognition questions administered by either the same or a different interviewer. Results from day 1 replicate previous findings with levels of recall and resistance to suggestibility increasing with age. Counter to predictions, correct recognition performance on day 2 was greater for some participants interviewed by the same as opposed to a different interviewer, and incorrect recognition was greater for all groups of participants for those interviewed by a different as opposed to the same interviewer. Results are discussed in terms of the role of context dependence on memory performance. Copyright © 2000 John Wiley & Sons, Ltd.     

Misleading Suggestions can Alter Later Memory Reports even Following a Cognitive Interview

Taking an immediate recall test prior to misinformation exposure can increase eyewitness suggestibility—a finding termed retrieval‐enhanced suggestibility. Here, we examined whether retrieval‐enhanced suggestibility would occur when participants were administered an immediate Cognitive Interview (CI). The CI is an investigative interviewing technique that consistently elicits more correct details in memory reports than standard interviews. In this study, participants watched a video of a crime and then completed a distractor task (control condition), a free recall test, or the CI. They then heard misinformation presented in a narrative. Participants produced more accurate memory details in the CI than in free recall despite spending equal time on both tasks. However, the CI also increased the later report of misinformation relative to the control condition. These results show that initial retrieval can increase subsequent suggestibility even when such retrieval occurs under relatively ideal conditions. Copyright © 2013 John Wiley & Sons, Ltd.     

Cognitive load and person memory: the role of perceived group variability

Two studies investigated the effects of cognitive busyness and group variability on participants' memory for stereotype‐related information. In Study 1, participants formed an impression of an experimentally created group that was either homogeneous or heterogeneous in composition. While learning about the group, half of the participants were made cognitively busy, the others were not. The results supported our prediction that stereotypical efforts on memory are moderated by both the availability of processing resources and the variability of the target group under consideration. Under optimal processing circumstances, participants' recollections were dominated by the perceived variability of the group in question. That is, participants displayed preferential recall for stereotype‐consistent information when they believed the group to be homogeneous in composition, but a tendency to recall more stereotype‐inconsistent information when they considered the group to be heterogeneous in nature. Under sub‐optimal processing conditions, however, a different pattern emerged. Now, participants preferentially recalled stereotype‐consistent information regardless of the perceived variability of the group. These results were largely replicated in Study 2 when the perceived variability of a real social group was manipulated. We consider the implications of these findings for contemporary theories of stereotyping. Copyright © 1999 John Wiley & Sons, Ltd.     

Individual differences in working memory capacity and search efficiency

In two experiments, we examined how various learning conditions impact the relation between working memory capacity (WMC) and memory search abilities. Experiment 1 employed a delayed free recall task with semantically related words to induce the buildup of proactive interference (PI) and revealed that the buildup of PI differentially impacted recall accuracy and recall latency for low-WMC and high-WMC individuals. Namely, the buildup of PI impaired recall accuracy and slowed recall latency for low-WMC individuals to a greater extent than what was observed for high-WMC individuals. To provide a circumstance in which previously learned information remains relevant over the course of learning, Experiment 2 required participants to complete a multitrial delayed free recall task with unrelated words. Results revealed that with increased practice with the same word list, WMC-related differences were eventually eliminated in interresponse times (IRTs) and recall accuracy, but not recall latency. Thus, despite still accumulating larger search sets, low-WMC individuals searched LTM as efficiently as high-WMC individuals. Collectively, these results are consistent with the notion that under normal free recall conditions, low-WMC individuals search LTM less efficiently than do high-WMC individuals because of their reliance on noisy temporal–contextual cues at retrieval. However, it appears that under conditions in which previously learned items remain relevant at recall, this tendency to rely on vague self-generated retrieval cues can actually facilitate the ability to accurately and quickly recall information.     

Speech Intelligibility and Recall of Spoken Material Heard at Different Signal‐to‐noise Ratios and the Role Played by Working Memory Capacity

We studied speech intelligibility and memory performance for speech material heard under different signal‐to‐noise (S/N) ratios. Pre‐experimental measures of working memory capacity (WMC) were taken to explore individual susceptibility to the disruptive effects of noise. Thirty‐five participants first completed a WMC‐operation span task in quiet and later listened to spoken word lists containing 11 one‐syllable phonetically balanced words presented at four different S/N ratios (+12, +9, +6, and +3). Participants repeated each word aloud immediately after its presentation, to establish speech intelligibility and later on performed a free recall task for those words. The speech intelligibility function decreased linearly with increasing S/N levels for both the high‐WMC and low‐WMC groups. However, only the low‐WMC group had decreasing memory performance with increasing S/N levels. The memory of the high‐WMC individuals was not affected by increased S/N levels. Our results suggest that individual differences in WMC counteract some of the negative effects of speech noise. Copyright © 2012 John Wiley & Sons, Ltd.     

Word-list-learning performance in younger and older adults: intra-individual performance variability and false memory

We investigated the word-list-learning performance of younger and older adults over 4 consecutive days at different times of day to study age-related differences in consistency of performance over time and the influence of circadian variation on performance. Eighteen younger (M age, 23.4 years) and 18 older (M age, 73.3 years) men and women participated. The start time of testing alternated between morning and early evening across the 4 days of testing. On each test day, participants learned a different list of 15 unrelated words over four learning trials. As expected, younger adults performed better than older adults on immediate recall, delayed recall, and recognition. Contrary to our expectations, time of day did not significantly influence recall or recognition performance in either the older or younger adults. Older adults did show a greater incidence of false memory (i.e., previously learned list intrusions in free recall and false alarms in recognition) than younger adults. Older adults also exhibited greater intra-individual performance variability on the measures of false memory across test days. This variability was not related to circadian variation. False memory and variability of performance have both been linked to frontal systems dysfunction. The findings presented here are consistent with the notion that changes in cognition with aging in part reflect age-related decline in frontal lobe function.