A series of five experiments examined the effects of irrelevant speech on proofreading and memory. Four of the experiments used a proofreading task and showed that the deleterious effects of irrelevant speech: (1) depend on the speech being meaningful, ( 2 ) are only present when the burden on short-term memory is low and (3) are manifested in a lower detection rate for non-contextual as opposed to contextual errors. Neither the spatial location of the speech (either in terms of spatial dispersion of sources or spatial movement of a single source) nor the intensity of the speech (in a range bounded by 50 dB(A) and 70 dB(A)) had any effect on proofreading. Late selection models of attention are favoured by the results in preference to models having arousal, short-term memory or early selection in attention as their basis. A final experiment showed serial recall for visual lists to be impaired by the presence of any speech-like sound (including reversed speech and speech in an unfamiliar language) which suggests a set of phenomena qualitatively different from those associated with proofreading. Throughout the article the practical consequences of the findings are emphasized.

This work was funded by a United Kingdom Economic and Social Research Council Grant to Christopher Miles and Dylan M. Jones. Many thanks to Neil Morris for discussions on the role of spatial encoding in working memory, Nelson Cowan for his erudite comments during the review process, Andy Tattersall for reading and commenting on the entire manuscript, and Kevin Hapeshi for his programming expertise.

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AcknowledgmentsThe authors would like to thank Dr. Richard Stephens and an anonymous reviewer for their suggested improvements to the manuscript. 3 AbstractThe finding that chewing gum can moderate stress and mood changes following a multi-task cognitive stressor (Scholey, Haskell, Robertson, Kennedy, Milne, and Wetherell, 2009) was re-examined. In a repeated measures cross-over design, thirty participants completed a 20-minute multi-tasking stressor on consecutive days, both with and without chewing gum. Both prior to and post stressor, participants provided salivary cortisol samples and self-rated measures of stress, state anxiety, calmness, contentedness, and alertness. Contrary to Scholey et al. (2009), chewing gum failed to

An experimental study of the effects of noise, nightwork and meals showed that these factors influenced different aspects of performance. Speed of performing a low memory load version of a visual search task was influenced by working at night but was unaffected by either noise or meals. A high memory load version of the search task was performed more slowly after consumption of a meal, both during the day and at night, but was not influenced by nightwork. Subjects working in noise produced more errors on the high memory load task than those working in quiet, but neither nightwork nor meals had significant effects on the number of errors. The only evidence of an interaction between factors was obtained in the high memory load search task, where noise reduced the size of the post-meal decline in speed. These results show that the effects of noise, nightwork and meals are largely independent, the exception being the beneficial effect of noise on post-lunch performance. They also demonstrate that the effects of all of these factors depend on the nature of the task being performed, and on whether speed or accuracy is the variable under consideration.

In a free recall experiment, participants learned lists of words in two physiological states: at rest and while exercising aerobically on a bicycle ergometer. Recall of the words was required in either the state consistent with learning or in the alternative state. Word lists learned during aerobic exercise were recalled best during aerobic exercise and vice versa. Greater changes in heart rate in the changed state conditions were associated with greater retrieval decrements. Recall levels for words both learned and recalled at exercise were equivalent to those for words both learned and recalled at rest. This finding rules out the possibility that exercise per se interfered with the original learning. The study is consistent with the view that state-dependent memory should be viewed as a particular form of cue-dependent memory.

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-minute 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 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), 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) that chewing gum negatively impacts short-term memory task performance.

Objectives: The finding that chewing gum can moderate state-anxiety under conditions of acute stress¹ has proved difficult to replicate. 2,4 The present study examines the extent to which chewing gum can moderate state-anxiety under conditions of acute social stress. Method:In a between-participants design, 36 participants completed a task comprising a mock job interview (a variation on the Trier Social Stress Task 3 , which included a mental arithmetic component) whilst either chewing gum or without gum. Self-rated measures of mood and anxiety were taken at baseline, after a 10-minute presentation preparation stage, after the 10-minute presentation, and following a 5-minute recovery stage.Results: Post-presentation measures reflected increased state-anxiety and decrease self-rated calmness and contentedness. Chewing gum attenuated the rise in state-anxiety whilst increasing self-rated alertness. Chewing gum did not affect contentedness or calmness. Conclusions:The findings indicate that chewing gum can act to reduce anxiety under conditions of acute social stress: a finding consistent with Scholey et al. 1 Furthermore, the data add to the growing body of literature demonstrating that chewing gum can increase alertness.1,2,4,5