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APPLIED ASPECTS OF AUDITORY DISTRACTION
|Year : 2010
: 12 | Issue : 49 | Page
|Effects of prior exposure to office noise and music on aspects of working memory
Andrew Smith, Beth Waters, Hywel Jones
School of Psychology, Cardiff University, 63 Park Place, Cardiff, CF10 3AS Wales, United Kingdom
Click here for correspondence address
|Date of Web Publication||21-Sep-2010|
Previous research has suggested that prior exposure to noise reduces the effect of subsequent exposure due to habituation. Similarly, a number of studies have shown that exposure to Mozart's music leads to better subsequent spatial reasoning performance. Two studies were conducted to extend these findings. The first one examined whether habituation occurs to office noise (including speech) and, if so, how long it takes to develop. Thirty-six young adults participated in the first study which compared effects of office noise with quiet on the performance of a maths task. The study also examined the effects of prior exposure to the office noise on the subsequent effect of the noise. The results showed that performance was initially impaired by the office noise but that the effects of the noise were removed by 10 minutes of exposure between tasks. The second experiment attempted to replicate the "Mozart effect" which represents an improvement in spatial reasoning following listening to Mozart. The study also examined whether the Mozart effect could be explained by changes in mood. Twenty-four young adults participated in the study. The results replicated the Mozart effect and showed that it was not due to changes in mood. Overall, these results show that prior exposure to noise or music can influence aspects of working memory. Such effects need to be incorporated into models of effects of noise on cognition and attempts have to be made to eliminate alternative explanations rather than just describing changes that occur in specific contexts.
Keywords: Habituation, Mozart effect, office noise, working memory
|How to cite this article:|
Smith A, Waters B, Jones H. Effects of prior exposure to office noise and music on aspects of working memory. Noise Health 2010;12:235-43
| Introduction|| |
Recent research on effects of noise has shown new developments in our knowledge base and theoretical approaches. For example, explanations based on changes of arousal have been interpreted in terms of stochastic resonance (where stimuli presented under a detection threshold can be detected in the presence of noise) due to the dopamine neural systems.  There have also been criticisms of the descriptive approaches seen in epidemiological studies which attempt to relate effects to overall exposure indicators without including the available knowledge on the possible underlying mechanisms.  Indeed, an alternative approach based on the hypothesis that long-term perception of environmental sound is determined primarily by short notice events (an instance of consciously perceiving sounds) has been able to mimic many of the noise annoyance effects.  It is possible to identify a number of mechanisms that possibly underlie the effects of noise on cognition.  Many environmental noise sources influence several different mechanisms and the effects reflect the precise combination induced by the specific mechanisms. For example, some acute effects of noise probably reflect changes in noise (notice events) in combination with stochastic resonance. Chronic effects of noise have been demonstrated in children tested in quiet  and these may actually reflect interference with speech perception which may lead to reduced cognitive functioning. , There may also be an interaction between acute and chronic effects which reflect state dependency, in that children used to a noisy environment do worse when tested in quiet, but better when tested in noise.  In addition, there is also the issue of habituation,  where prior noise exposure leads to a reduced effect of subsequent exposure. The topic of habituation is considered in the first study described here. Effects of prior exposure are also investigated in the second experiment which considers an area that has recently received considerable attention, namely, the importance of investigating positive sound exposures.
In summary, the aim of these studies was to test the hypothesis that it is crucial to examine prior exposure to noise or music as these influence the effects of subsequent noise exposure or even subsequent testing in quiet. It is well-established that effects of auditory exposure are task specific  and these studies examined different aspects of working memory which have been shown to be sensitive to office noise and Mozart's music. The aim of the studies reported here is to consider different after-effects of exposure to different sounds. This would inevitably require consideration of a range of different theoretical approaches rather than the application of overlapping views.
| Experiment 1: Office Noise and Mental Arithmetic|| |
With an increasing popularity of open plan office layouts and the large number of employees based in office environments, background noise at work has become an important issue with regard to worker performance, satisfaction and occupational health. Noise is reported to be one of the most widespread environmental problems in work places, including offices.  Whilst it is true that office workers seldom run the risk of developing hearing damage, noise may still create serious problems at levels far below those at which such damage may occur.  Nevertheless, despite the potential seriousness of the problem, systematic research on such problems has been sparse in the work place. The few studies that have addressed the problem have shown that excessive background noise may result in office worker discomfort and stress, lack of concentration, low levels of performance, and reduced efficiency. , Moreover, some researchers have even suggested that the occupational stress caused by environmental stressors such as noise can result in long-term physical problems in the worker such as musculoskeletal disorders and high blood pressure.  In contrast to this, research has shown that office sounds including both speech and other office noise can successfully be habituated to after a period of 20 minutes. , The main aim of this study was to add to this data and identify the length of prior exposure required to produce habituation to office noise.
The development of the open plan office in the 1960s and 1970s accentuated the noise problem and led to some research, , but noise is still given a very modest role in models developed for the analysis of health and well-being of office workers. Nemecek and Grandjean  surveyed 15 landscaped offices in Switzerland and a number of ergonomic measurements were made concerning noise, lighting and room climate. Nemecek and Grandjean  found that co-workers' talk was the noise that most often caused complaint. This source of disturbance was mentioned by 46% of the workers, whereas 25% mentioned office machines, 19% telephones, 7% the coming and going of people and only 3% external noise as complaints. Other research  has also found co-workers to be the most often mentioned noise source in offices and the frequency of complaints increased with the number of people sharing the room. In the landscaped offices studied by Boyce,  telephone signals and conversations were the most frequently mentioned sources of noise disturbance. Among the office workers who took part in the study by Nemecek and Grandjean,  52% considered conversations the most disturbing noise, except when the windows were opened in which case traffic noise was judged as worse. In a more recent study,  200 office workers were asked about office noise disruption. Of these, 54% were bothered by background noise made up of background conversation and telephone chimes. Banbury and Berry  found that 99% of a sample of 88 employees reported that their concentration was impaired by components of office noise, especially telephones left ringing and people talking in the background. There was no evidence for habituation to these sounds. Beaman  has reviewed the effects of auditory distraction in the workplace and concluded that the effects of extraneous background noise on cognitive performance can be considerable. However, reduction of these effects requires consideration of the population exposed to noise, the auditory environment, nature of the cognitive task and nature of the noise. Such considerations apply to most areas of noise and cognition and imply considering a range of different phenomena in order to present a profile of effects.
The above studies clearly show that the detrimental effect disturbing background noise has on individuals in their working environment is a well-documented problem.
Colle and Welsh  first identified the irrelevant speech effect within the cognitive psychology literature. This effect has usually been studied using serial recall of 7-9 digits or consonants. The irrelevant speech effect was initially interpreted in terms of phonological confusion.  Morris and Jones  were the first to address the issue of habituation to irrelevant speech, in an attempt to isolate some of the features of speech that produce habituation. They found that the effect of irrelevant speech, which impairs performance on the primary task when there is no habituation phase, is reduced markedly in conditions where the speech used in the habituation phase is the same as that used in the test phase. Morris and Jones interpreted their results in relation to Salame and Baddeley's  account of the irrelevant speech effect, as their work preceded the formulation of the changing state hypothesis  and the Object-Orientated Episodic Record (O-OER) model.  Jones, Farrand, Stuart, and Morris  have suggested that some factor other than phonological confusion may be responsible for the disruptive effects typically seen with irrelevant speech. Since the work of Salame and Baddeley,  studies have shown that the critical factor in determining disruption of serial recall is whether the irrelevant auditory input contains changing state information, that is, each physical unit within the sound stream, such as a syllable or a tone burst, must be different to the unit that precedes it.  A changing state sequence of tones, each one a different pitch to the one that precedes it, produces substantial disruption of short-term serial recall, but repeated tone bursts produce little or no disruption. This explains why continuous broadband noise fails to be disruptive because it does not meet the criterion for changing state. The process of interference with serial recall is explained by the co-existence in short-term memory of objects from deliberate sub-vocal rehearsal of the visual material and objects of auditory origin derived from the irrelevant stream. Disruption is the result of a conflict in organization between the two streams of information; one from the material that is deliberately rehearsed and the other from the automatic, obligatory processing of the irrelevant sound. Jones et al,  argue, therefore, that any sounds that conform to the criteria for changing state have the potential to cause a disruption similar to those seen with speech. The changing state hypothesis provided the basis for Jones  Object-Orientated Episodic Record (O-OER) model of short-term memory. There are two components to the model: objects and the temporal order of objects. Objects are viewed as abstract representations of events in the world which are not modality specific. Therefore, the model does not suggest that there are separate processing systems; all objects are represented similarly. The temporal order of objects is encoded in the episodic pointers which point from object to object navigating through representation of space. Serial recall relies on these pointers and is affected by interference between the episodic pointers in the irrelevant sequence (auditory stimuli) and those in the target sequence (to-be-remembered stimuli). The auditory stimuli have obligatory access to the blackboard. Visual stimuli gain access through serial rehearsal and links between the visual items are created. A sequence of changing auditory items attracts separate objects for each item, whereas a single repeated auditory item attracts only one object, therefore affecting performance less. This results in navigation being more affected by changing state rather than steady-state auditory material.
There is a large body of research supporting the changing state hypothesis and subsequent O-OER model, which also fail to support Salame and Baddeley's  explanation for the irrelevant speech effect. With the hope of shedding light on these conflicting views, Banbury and Berry  investigated habituation and removal of habituation to speech and office noise with a memory for prose task. Banbury and Berry  reported three experiments, all presenting a variety of natural and contrived background noises during completion of a task and in a habituation period. Their first experiment investigated whether 20 minutes of exposure to speech (continuous, repeated or meaningless) can reduce the disruption caused by background speech on the memory for prose task. They found that 20 minutes exposure to background speech can be habituated to and that the meaning and repetition had no effect on the degree of habituation seen. The second experiment used a similar design to investigate whether office noise that does not contain speech can be habituated to. Again, Banbury and Berry  found that office noise without speech can be habituated to after a time period of 20 minutes. Finally, the third experiment investigated habituation, with a change of voice and a short period of quiet. The results of this final experiment revealed that a 5-minute period of quiet, but not a change in voice, was sufficient to partially restore the disruptive effects of background noise previously habituated to. In summary, their study extended the literature in this area by examining habituation to more complex sounds combined with performance of more complex tasks. The results of their study showed that irrelevant speech and office noise that does not contain speech can be habituated to after a prolonged exposure to the noise stimuli.
Banbury and Berry  propose that habituation effects can be accounted for by the addition of a filter mechanism before the formation of links and objects on the episodic surface. After prolonged exposure to the irrelevant sound stream, the filter becomes impermeable, allowing the formation of objects on the episodic surface but not the links between them. Disruption by the irrelevant sound stream is therefore impossible as there is only one set of links. This updated O-OER model can account for little or no disruption seen after prolonged exposure to the irrelevant sound stream.In contrast to the findings reported by Morris and Jones,  several studies have now shown that the irrelevant sound effect with visual-verbal serial recall does not habituate. , In addition, the habituation idea is often related to the notion that irrelevant sound/speech produces disruption because it causes an "orienting response" (OR) that leads to attentional capture.  Irrelevant sounds produce disruption because they recruit processing resources (or attention) away from the focal task by automatically attracting attention via an OR (an approach based on Sokolov's  theory of a neural model; Cowan,  ). There is good evidence now that the changing-state effect in visual-verbal serial recall is not produced by ORs  and hence will not habituate.  However, habituation of ORs may indeed occur for other tasks,  but this is because for those tasks (memory for prose and mental arithmetic being possible examples)-in contrast to the visual-verbal serial recall-disruption by sound may indeed be underpinned in part by ORs.
The first experiment reported in this article was designed specifically to extend the evidence provided by Banbury and Berry  addressing the issue of habituation to office noise, in an attempt to identify how long the filter takes to attenuate to the irrelevant sound stimuli. This was achieved by using the evidence from studies previously conducted in this area. Banbury and Berry's  study revealed that office noise is habituated to in the laboratory after a period of 20 minutes. This study aimed to extend this finding and look more closely at the time it takes for the participants to habituate to office sounds using a working memory task, namely mental arithmetic. The task was chosen because it could easily be controlled in the laboratory and would require no prior training. The task required the reading of each newly presented digit and operator, updating the current subtotal, and keeping track of this as the next digit and operator was calculated. It was predicted that office noise would have a disruptive effect on the mental arithmetic task.
A total of three conditions were used. Participants in the continuous noise condition heard noise during the presentation of all mental arithmetic tasks and the intervening habituation periods. Those in the noise control condition heard the noise during the presentation of the mental arithmetic tasks but not during the intervening habituation periods. Finally, participants in the quiet control condition received no noise during the experiment. The intervening habituation periods were 5 minutes in duration (a total exposure of 25 minutes).
The study was carried out with the approval of the Ethics Committee, School of Psychology, Cardiff University, and with the informed consent of the volunteers. Thirty-six undergraduate participants from Cardiff University took part in this experiment (males = 11, females = 25). Participants were aged between 18 and 25 years (mean = 20 years). All were native English speakers and reported normal hearing. The majority of the participant pool volunteered to participate in this experiment, the remaining gained course credits for their participation.
The mental arithmetic task was presented to each participant in a five-part pack. For each of the five mental arithmetic tasks, six sets of 15 sums were composed. Half of the sets were addition only: e.g. 4 + 6 + 1 + 5 + 3 + 8 + 7 + 5 + 3 + 9 + 2 + 4 + 9 + 7 + 5. The remainder included both addition and subtraction operations:e.g. 9 + 6 - 3 + 4 - 9 + 3 - 6 + 8 - 6 + 2 + 4 - 7 + 5 - 2 + 8. Participants were requested to rehearse covertly (rather than overtly) any calculations they needed to perform.
All noise recordings were presented at a sound level of 65 dB which is comparable with a normal conversation within 1 m found in an office setting.  The office noise was presented to each participant through headphones. The office noise was recorded in an office where speech sounds and other office duties (telephone, beeping and shuffling) could be heard. The speech contained both male and female voices talking sporadically throughout the recording. Headphones were worn throughout the experiment. Participants were instructed to ignore any background noise that was presented through the headphones.
Habituation blocks were manipulated within participants, whereas noise conditions were manipulated between participants. Participants in the continuous noise condition heard irrelevant noise during the presentation of all five mental arithmetic tasks and the intervening habituation periods. Those in the noise control condition heard the irrelevant noise during the presentation of the mental arithmetic tasks but not during the intervening periods. Finally, participants in the quiet control condition received no noise stimuli during the experiment. The dependent variable was the number of correct responses on each mental arithmetic task. The order of presentation of the tasks was counterbalanced. Twelve participants were allocated at random to each of the three test groups.
Participants were tested in groups of between two and six in a sound proof laboratory. The experiment consisted of distinct phases: the completion of the first mental arithmetic task, a habituation period to office noise (or no noise) for 5 minutes, the completion of the second mental arithmetic task followed by a further 5-minute habituation period before a third mental arithmetic task. This process of 5 minutes habituation period and 2 minutes testing period continued until all five mental arithmetic tasks had been completed. Participants were instructed that they had 2 minutes to answer as many maths problems as quickly and accurately as possible. The maximum score that participants could achieve on each of the tasks was six. The habituation phase consisted of a total of 20 minutes where participants were given no other task than to wear the headphones and stay in the room in silence. All participants were debriefed at the end of each testing session.
The group mean accuracy scores for the mental arithmetic tasks are shown in [Table 1] below. These results provide a fairly clear picture. When participants are exposed to office noise, they show signs of disruption with poorer performance but after a 10-minute habituation period, their performance improves.
A noise condition ΄ habituation block mixed analysis of variance (ANOVA) showed a significant effect of noise conditions [F (2,33) = 8.3, P < 0.05], a significant effect of habituation block [F (4, l32) = 6.3, P < 0.05] and a significant interaction [F (8, 132) = 4, P < 0.05]. Analysis of simple effects revealed significant differences on the test blocks in the noise condition [F (4,132) = 13.2, P < 0.05]. Performance in noise was significantly better after the 10-minute habituation exposure than the initial test block [F (1,123) = 27.4, P < 0.01].
This study aimed to extend the work of Banbury and Berry  by looking at the time taken by participants to habituate to office noise. The results clearly show that the disruptive effect of background noise can be fully habituated to after a 10-minute period of exposure. The results from the mental arithmetic task indicate that office noise with speech and office sounds had a significantly detrimental effect on the participant's ability to perform mental arithmetic. Performance in the quiet control condition was significantly better throughout than performance in the noise control condition. In the continuous noise condition, performance improved significantly after 10 minutes habituation time and improved to the same level of performance as in the quite control condition. The results from this study support the findings from Banbury and Berry  showing that office noise can disrupt performance on working memory tasks (i.e. mental arithmetic) but that this disruption can be habituated to after a period of time in noise. This study has gone on to show that participants fully habituated to the office noise following 10 minutes intervening exposure. The changing state hypothesis and the subsequent O-OER model  provide appropriate explanations of the effects seen in this experiment.
The present study has provided evidence that office noise can be fully habituated to after an intervening exposure period of 10 minutes. However, despite our ability to habituate to office noise in the laboratory, a number of observational studies report that office workers are unable to adjust to the disruptive effect of background noise. ,,, The apparent difference in findings from laboratory studies (ability to habituate to office noise after 10 minutes exposure) and research in the applied setting (continued disruption from background noise) can be accounted for in the following way. Banbury and Berry  found that 5 minutes silence amongst background irrelevant noise was enough to restore the disruptive effects of the noise. The results from this study have shown that it takes 10 minutes for participants to fully habituate to office noise and Banbury and Berry's research has revealed that 5 minutes of silence leads to a reversal of this habituation. Further studies in this area need to investigate real office tasks carried out by office workers performing in the real world setting as opposed to the laboratory. In conclusion, the results from this study support the notion that participants can habituate to office sounds after a period of 10-minutes and this result is in line with previous work carried out in this area. Further research is clearly required in this area. For example, the impairments observed in the office noise initially might be a mixture of the changing state effect (due to the irrelevant speech) and distraction due to other aspects of the noise. It may be the case that it is only the latter that is susceptible to habituation. Such an explanation has important implications for the effects of real-life noise sources and moves the focus away from specific exposures (changing state speech) and specific cognitive processes (e.g. serial recall).
In order to reach conclusions about the effects of prior exposure to sound, one needs to consider a range of different exposures and outcomes. Early research on noise after-effects demonstrated impaired performance following exposure to uncontrollable or unpredictable noise.  However, studies of prior exposure to certain types of music have suggested that aspects of performance may be improved and the second study reported here examines prior exposure to Mozart's music to determine whether this influences subsequent performance in quiet.
| Experiment 2: The Mozart Effect|| |
The findings of Rauscher, Shaw, and Ky  that performance on spatial ability tasks was increased after listening to a Mozart sonata became a widely publicized phenomenon. Thompson, Schellenberg, and Husain  state that the view that music makes people more intelligent is a direct result of this finding. The publicity that Rauscher et al.'s  finding received is attributed to excitement over its possible implications. If music makes people more intelligent, it could improve the performance of office workers, children, students, or anyone attempting to increase their intelligence. Many subsequent studies were critical of the findings of Rauscher et al, claiming the results could be an example of how positive mood and arousal improve performance. ,,,, This study attempted to replicate the original findings of Rauscher et al,  and to discover whether the improvement on spatial-ability tasks is indeed a Mozart effect, or an example of positive mood and arousal.
Rauscher et al, reported that participants who listened to Mozart's sonata for two pianos (K448) before completing spatial reasoning tasks performed better on these tasks than after listening to a relaxation tape or sitting in silence. This came to be known as the Mozart effect. Rauscher et al,  stated that after listening to the Mozart sonata, participants' IQ scores increased 8-9 points over the other two conditions. Rauscher, Shaw, and Ky  suggested a neurophysiologic explanation for the findings, the Trion model of the cortex. The Trion model assumes that the cortical column within the cortex consists of smaller columns called trions. A group of trions has excitable combinations or symmetries of firing patterns, and these combinations may influence and be a component of higher brain function. The Trion model predicts that listening to music which is complex in nature creates a combination of firing patterns akin to those that occur in spatial-temporal reasoning tasks. When a complex piece of music is listened to before completing a spatial-reasoning task , ) it acts as a form of exercise or priming of the cortical firing patterns. Performance on the subsequent spatial-reasoning task is improved due to this priming effect. Subsequent studies mainly by the authors of the original findings serve as a further support for the theory. In response to criticism by Chabris  , Rauscher  described a study in which rats that listened to the Mozart sonata for two pianos, K448, for 60 days learned their way around a spatial maze quicker and with fewer mistakes than control rats. Rauscher  stated that these findings were unlikely to occur through enjoyment or arousal. Rauscher's studies received substantial criticism and challenge for the results obtained and theories suggested. Subsequent attempts by many researchers to replicate the findings failed. For example, Stough et al, failed to find a significant effect of listening to Mozart improving spatial abilities, although the task used was the Raven's Progressive Matrices which is a test of abstract reasoning more than spatial processing. Stough et al,  attributed the non-significance of the findings to this inconsistency in tests. Steele, Bass, and Crook,  however, were extremely critical of the reported Mozart effect, after failing to find a significant result despite replicating the exact procedure outlined by Rauscher et al. , Another study  has failed to replicate the effect in children. Chabris  performed a meta-analysis on every published study in this area using Mozart-versus-silence comparisons. Chabris  found that the effect sizes of the 20 studies concerned gave a mean cognitive improvement of only 1.4 IQ points, a great deal less than the 8-9 IQ point difference that Rauscher et al. ,
Chabris  also challenged Rauscher et al.'s  neurophysiologic basis for the effect, namely, the Trion model. Chabris  argued that the rotation of images, as is done in the tasks used for testing spatial abilities, is a function of the right cerebral hemisphere, while cognitive arousal is also a function of the same brain area. Chabris  suggested that the Mozart effect only works because it is a form of inducing a positive mood and increased arousal. Being in a positive mood activates and primes the right hemisphere, resulting in improved spatial processing. Results from a study by Nantais and Schellenberg  support this view. They attempted to replicate the original findings of Rauscher et al, and extended it by using the music of Schubert as well as Mozart (half of the participants listened to Mozart and the other half listened to Schubert). In a second experiment, participants read an extract from a Stephen King story instead of sitting in silence, rating how enjoyable they found the extract and the music they listened to. The reasoning behind this was that previous experiments on the Mozart effect had alternative conditions that induce boredom. In the original experiment, for example, participants listened to Mozart, a relaxation tape, or sat in silence. Nantais and Schellenberg  suggested that the alternative conditions used in this experiment were boring for participants, and results gained were from a simple increase in performance due to enjoyment of the Mozart condition, or positive arousal. Nantais and Schellenberg  found that listening to Mozart or Schubert led to better performance than when sitting in silence. They concluded that the Mozart effect could be attributed to any enjoyable piece of music composed in the era, and was not attributable to the music of Mozart per se. This was supported by the results from a second experiment. Participants did not perform significantly better in either condition (Mozart or story), but performed significantly better in the condition rated as most enjoyable. Nantais and Schellenberg  explain the results either in terms of spatial-temporal processing being improved by positive arousal, or performance being disrupted and becoming poorer in non-arousing conditions.Positive mood has regularly been suggested as an explanation for improved performance. In a series of four experiments on the effects of positive effect on creative problem solving, Isen, Daubman, and Nowicki  concluded that if arousal is the cause of elation, it results in participants thinking of ways that solve problems of a creative nature. They suggest that positive affect increases participants' likelihood of finding new ways of combining material, and finding "relatedness between divergent stimuli". In the type of spatial-temporal ability tasks used in studies of the Mozart effect, the positive affect might improve performance, as the tasks are problem-solving tasks that require the combining of material and finding relatedness in stimuli.
The arousal/mood explanation of the Mozart effect also gains support from studies on brain-damaged individuals. Ditunno and Mann  investigated whether mental rotation is specialized in the right hemisphere. The mental rotation of an object is part of what is required in spatial-temporal ability tasks. They found that in non-brain damaged participants, stimuli presented in the left visual field (located by the right hemisphere) were located quicker and more accurately than when they were presented in the right visual field (located by the left hemisphere). A significant difference occurred when stimuli were presented at large angles, suggesting that the right hemisphere is more important than the left in mental rotation tasks, though the task is not specialized to the right hemisphere. Ditunno and Mann  sought confirmation of this by studying brain-damaged participants. They found that participants with parietal lesions in the right hemisphere made significantly more errors on a mental rotation task than patients with a lesion in the left hemisphere and controls. Robertson, Mattingley, Rorden, and Driver  also provide support for an arousal explanation of the Mozart effect in that they found that lesions in the right hemisphere had an effect on tonic alertness and the ability to uphold a consistent level of arousal. In addition, they argue that evidence suggests spatial attention to be reliant upon right hemisphere brain areas, and when lesions in that area occur, deficits in spatial attention appear.
Thompson, Schellenberg, and Husain  tested the hypothesis that the Mozart effect reflects a change in positive mood by comparing performance on spatial-temporal ability tasks after listening to the Mozart sonata (K448), Albinoni (sad music) and silence. Results showed that participants performed better on a spatial ability task after listening to Mozart than after sitting in silence. When music by Albinoni (chosen as a "sad" piece of music) was listened to instead of Mozart, this effect disappeared. Significantly higher levels of positive arousal and mood and significantly lower ratings of negative mood were found in those participants who had listened to Mozart as opposed to those who had listened to Albinoni. Thompson et al, stated that these results show that the Mozart effect is an example of increased performance due to positive arousal and mood.
This study attempted to resolve the inconsistency found in the studies by Rauscher et al, , and the studies of Chabris  and Thompson et al.  This involved the following approaches.
- Comparing the performance of participants on spatial-temporal ability tasks in three conditions: (a) after listening to Mozart's piano sonata for two pianos, K448, (b) after a positive mood induction as used by Teasdale and Russell  and (c) after sitting in silence.
- Measuring mood ratings of participants, to see if the Mozart sonata (K448) creates a positive mood which could account for the improvement in spatial reasoning.
The study was carried out with the approval of the Ethics Committee, School of Psychology, Cardiff University, and with the informed consent of the participants.
Twenty-four undergraduate students of Cardiff University participated in the study. Male and female participants, with a mean age of 20 years, took part in the study.
The study used a within-subjects design, with each participant completing each of the three conditions. The order of the conditions was counterbalanced, with four participants being used in the six possible combinations of the three conditions.
The music used in the Mozart condition was the same as used in the earlier studies, which is Mozart's Sonata for Two Pianos in D Major, K448. 
Positive mood induction
In order to attempt to induce a positive mood, participants read a series of elation induction statements. Participants were instructed to try and get into the moods implied by the statements and to concentrate on those statements that they felt worked best for them, as specified by Teasdale and Russell. 
This involved sitting in silence in the laboratory.
Participants were asked to rate their mood at the beginning of testing, after the condition manipulation and at the end of testing, using visual analog rating scales taken from Smith, Sturgess and Gallagher.  These scales measured the factors of alertness, hedonic tone and anxiety.
Spatial ability tasks
The task used in this study was the Revised Minnesota Paper Form Board (RMPFB) Test  which had previously been used to study the Mozart effect. This test was chosen because it is one of spatial-temporal processing, as is the paper folding and cutting task in the Stanford-Binet intelligence test used by Rauscher et a1. There are four versions of the test and three of these were used in this study.
Before commencing the test, participants were given a brief account of the tasks and the order of tasks that they were going to undertake. More detailed instruction was given before the completion of each individual task. The participants' first task was to rate their mood using the visual analog scales. Participants then carried out one of the three conditions of the independent variable, listening to the Mozart sonata, reading positive mood statements or sitting in silence. These lasted for 10 minutes. Participants then rated their mood again. They were then instructed that they had 10 minutes to complete as many questions as they could on the Revised Minnesota Paper Form Board test (RMPFB). Participants then rated their mood for the third time using the same method previously employed. This procedure was employed in each of the three conditions.
Spatial ability task
[Table 2] shows that participants had higher scores (difference between correct and incorrect answers) on the RMPFB Test in the Mozart condition than in the other two conditions as well as were answering more questions and answering more questions correctly.
ANOVAs were carried out with condition (three levels) as the within-subjects factor, and testing order as the between-subjects factor. There was a highly significant effect of condition [F (2, 36) = 9.576, P < 0.0001] on the difference score of the RMPFB test. Post hoc Tukey tests showed that performance in the Mozart condition was better than both the silence and mood induction conditions. The second analysis was conducted on the number of questions answered on the RMPFB test. Results showed a significant effect of condition [F (2, 36) = 4.930, P < 0.05]. Again, there were significant differences between the Mozart condition and the other two conditions. The analysis of the number of correct answers also showed a significant effect of condition [F (2, 36) = 9.988, P < 0.001], with the Mozart condition leading to better performance than the other two conditions.
There was no effect of condition on ratings of alertness or hedonic tone with neither the mood induction nor Mozart's music having a significant effect. However, there was a significant effect on ratings of anxiety [F (2, 36) = 3.54, P < 0.05]. Post hoc Tukey tests showed that there were no significant differences between conditions on the first or third mood rating (at the beginning and the end of testing). However, participants felt calmer after listening to Mozart than after either silence or the mood induction conditions.Differences in performance of the spatial ability task did not reflect the mood scores.
The results presented above indicate that this study has found a Mozart effect, replicating the results of Rauscher et al.  Participants performed significantly better on the spatial-temporal ability tasks presented after listening to Mozart than in the other two conditions, which was as predicted. There was evidence to suggest that the Mozart effect is not due to positive mood arousal as suggested by Chabris  and Thompson et al.  Indeed, the mood ratings showed no evidence that listening to Mozart increased alertness or hedonic tone. The basis of the reports advocating that the Mozart effect is an example of positive mood and arousal improving performance is that by replacing the Mozart sonata with music that is equally as enjoyable,  the Mozart effect remains, but replacing it with music that is sad  makes the effect disappear. None of these studies, however, take into account the complexity of the music which is a critical point of Rauscher's explanation of the effect. Nantais and Schellenberg  found that by replacing the Mozart sonata with music by Schubert, an effect of equal magnitude was found, making the assumption that this was because Schubert's music was equally as enjoyable as Mozart's sonata. The fact that the music of Schubert is from the same era and has the same complexity as that of Mozart is something that was not considered by Nantais and Schellenberg.  Similarly, Thompson et al,  make no mention of the complexity of the sad music chosen by them (Albinoni Adagio in G minor - which is a simple piece of work).An important question is what exactly constitutes a complex piece of music? Steele et al raise this issue of complexity of the music chosen, citing a study which showed a significant improvement in spatial ability tasks following listening to the works of Yanni, who is a modern composer of complex music. It is suggested that conclusive evidence on the Mozart effect will not be found until the issue regarding the complexity of music is resolved, and performance on a spatial ability task after listening to Mozart's sonata for two pianos, K448 is compared to performance after a successful, non-musical, positive mood induction.
| Conclusions|| |
The overall aim of this research was to test the hypothesis that prior exposure to certain types of noise and music can influence subsequent performance of working memory tasks. In addition, the research examined whether such changes could be accounted for by changes in mood. Overall, the results confirmed that effects of office noise may be reduced by prior exposure to the noise. In real-life situation, it is likely that the noise environment will be constantly changing and this will perpetuate the negative effects of noise because habituation is rapidly removed by subsequent reduction in the noise. This is yet another piece of evidence that suggests a greater consideration of changes in the noise rather than giving emphasis on intensity.
The second study showed that prior exposure to Mozart improved subsequent performance on a spatial reasoning task. This, again, confirms the previous findings and the study also ruled out alternative explanations in terms of the effect reflecting mood changes. Further research on this topic is now required. The Mozart effect is thought to reflect the complexity of the music but the problem is that complexity is difficult to define. What is now required is an acoustic model of musical complexity that can generate stimuli that will or will not lead to cognitive improvements.
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School of Psychology, Cardiff University, 63 Park Place, Cardiff, CF10 3AS Wales
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2]
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