Abstract
The relationship between exercise-induced arousal and cognitive performance (CP) has been studied since the mid-19th century. A total of 416 students (mean age 20.73 years, SD = 7.28), split into three groups performed a letter-detection task after a period of physical exercise (PE). Group one performed no PE, group two performed one-minute of PE, and group three performed two-minutes of PE. The results reveal that group two performed better than group one, and group three performed better than group two. The results suggest that even minimal PE can have an overall positive effect on CP.
Revisiting the relationship between exercise-induced arousal and post-exercise cognitive performance
The relationship between exercise-induced arousal and CP has been studied since the mid-19th century (Tomporowski & Taylor, 2013). Initially, to determine if a relationship existed and more recently to unravel the complexities of the established relationship. Early in the 20th century, psychologists Yerkes and Dodson (1908) hypothesised that the relationship between PE and CP, if plotted, should approximate an inverted-U shaped function (Arent & Landers, 2003; Tomporowski, 2003) where optimal CP should be achieved by moderate arousal, and that adverse effects on resting state CP would be observed at either of the two poles of no arousal and exhaustive arousal respectively (Arent & Landers, 2003).
When considering complex systems and the events and processes within them, is it essential that the core terms be clearly defined as is relevant to the context of consideration. According to Sage, (as cited in Arent and Landers) arousal is defined as “an energising function responsible for harnessing the body’s resources for intense and vigorous activity” (2003, p. 437). A person’s level of arousal exists at a point on a continuum ranging from comatose to hysterical (Arent & Landers, 2003; Sage, 1984). Cognition can generally be defined as the conscious use of memories to formulate flexible patterns of behaviour to solve or navigate obstacles in everyday life (Tomporowski & Taylor, 2013), but a general definition only provides a low-resolution impression that glosses-over the six cognitive task categories (CTC) that comprise cognition; information processing, reaction time, attention, crystallised intelligence, executive function, memory (Chang, Labban, Gapin, & Etnier, 2012). Each of the CTCs can be further divided into more precise components, which have been studied to varying degrees. This experiment considers the sub-category breakdown of executive function into the following three components: (1) working memory management, (2) inhibition of distractions (internal monologue/dialogue, external stimuli, emotional responses and automatized reactions), and (3) cognitive flexibility (Audiffren & André, 2015). Executive function is essential for self-regulation which is a person’s ability to adaptively orient themselves and their behaviour in the context of dynamic conditions for a period to achieve a goal (Audiffren & André, 2015).
Despite peer criticism of conceptual and methodological design features and some contrary results from experiments carried out since research began, the inverted-U hypothesis is generally supported by an ample corpus of data compiled from the many studies (Arent & Landers, 2003; Chang et al., 2012; Lambourne & Tomporowski, 2010). The support is general in that the consensus is that generally, PE up to a point will facilitate cognitive performance improvements until optimal CP is achieved, after which any further PE will result in CP inhibition. Specifically though, the corpus of research data suggests that the link between PE and CP is moderated by multiple variables such as; the mode, intensity and duration of the PE, when the CP is tested in relation to PE, which variables are being measured, which CTCs are being tested, the design of the experiment (Chang et al., 2012; Lambourne & Tomporowski, 2010; Smith, Potter, Mclaren, & Blumenthal, 2013; Tomporowski, 2003), and when considering executive function there is an absential element of consciousness that should be noted when considering its role in goal-directed behaviour (Deacon, 2013).
Previous studies have focused on the effect of moderate, high, and exhaustive arousal on CP, this experiment examines if there is any effect from mild arousal on CP. By conducting the task directly following the PE, this experiment tests the immediate effects of PE on the performance of specific cognitive resources required to perform a letter-detection task. If the inverted-U hypothesis holds true, it is expected that there will be two small increments of improvement in CP from the second and third groups. This prediction is based on the components of cognition used in a letter-detection task against the components of cognition that have been shown to improve immediately following PE (Audiffren & André, 2015; Chang et al., 2012; Coles & Tomporowski, 2008; Giles & Terrell, 1997; Lambourne & Tomporowski, 2010; McMorris & Hale, 2015; Tomporowski, 2003).
Method
Participants
A total of 416 students (mean age 20.73 years, SD = 7.28) from the School of Applied Psychology participated in this experiment as part of their course requirements. Most demographic and socioeconomic factors (such as but not limited to; sex, literacy level, fitness level) were not considered for this experiment. The participants were separated into three groups; a control group (n = 148) and two experimental groups (n = 131 and n = 137).
Materials
Each participant was handed a journal article about letter-detection tasks. Participants were seated on chairs for the experiment and used a pen/pencil to complete the letter-detection task. All timed periods were measured with a stopwatch to ensure accuracy.
Design
This experiment is a between-subjects design where the independent variable varies three ways; Group one: no air-cycling; Group two: one-minute air-cycling; Group three: two-minutes air-cycling. The dependent variable being measured is the CP of the participants in circling as many “i”s as they detect in the two-minutes allowed.
Procedure
Upon entry to their tutorial room, participants were given a letter-detection paper and randomly allocated to one of three groups. Group one was the control group (n = 148) that completed no PE. Groups two and three were experimental groups that completed two different durations of PE (n = 131 and n = 137), one and two-minutes respectively. Group three participants were instructed to commence PE first, followed by group two participants one-minute later. After the second minute elapsed, groups two and three were instructed to cease air-cycling, then all three groups were asked to commence the letter-detection activity. For the letter-detection component, tutors instructed all participants to read the article as though they would have to answer questions about it afterwards. Participants were instructed to circle as many “i”s as they detected while reading the article and were asked to stop after two-minutes had elapsed. Tutors then asked all participants to count the number of “i”s identified, record this number along with their age and group number on a piece of paper that tutors collected at the end of the tutorial.
Results
Figure 1 overleaf displays the mean letter-detection scores for each of the three exercise groups. Group one (M = 63, SD = 11) exhibited the lowest performance of the three groups, and group three (M = 92, SD = 13) performed the best on the letter-detection task. Group two (M = 76, SD = 8) performed better than group one but did not perform as well as group three.
Figure 1. Mean letter-detection scores for the three exercise groups.
As shown in Table 1 overleaf, two independent-samples t-tests were conducted to compare the CP of group one with group two, and the CP of group two with group three. Analysis reveals a significant difference in the scores for group one (M=63, SD=11) and group two (M=76, SD=8) conditions; t(49)= 3.94, p <.05. The mean number of “i”s circled by group two was greater than group one, but the p-value is not much smaller than .05, so the significance is only small which resulted in a slightly higher mean score for group two. There was also a significant difference in the scores for group two (M=76, SD=8) and group three (M=92, SD=13) conditions; t(105)=10.68, p < .001. The mean number of “i”s circled by group three was also greater than group two, but the p-value is much smaller than .05, so the significance is much greater which resulted in a higher mean score for group three. The group that showed the most score variability is group three while group two had the least variability with most scores falling closer to the mean.
Table 1. Independent Sample t-tests Between Exercise Group and Cognitive Performance
Discussion
The objective of this study was to investigate the effect of mild arousal on CP immediately following PE. The results reveal that group two performed better than group one, and group three performed better than group two in the letter-detection test. At low-resolution, it appears that the results support both hypotheses.
While the letter-detection test uses all CTCs, it only utilises particular components of each CTC; visual search, task switching, choice reaction time (CRT), verbal/word fluency, verbal working memory, sequential memory, distinct attentive resources associated with IQ. The attentive resources specific to the letter-detection task are visual matching (perception speed), pattern recognition (visual memory), and letter/pattern matching (perceptual speed). Of these components and resources, only sequential memory is adversely affected (Chang et al., 2012). The following components are positively affected; visual search (Chang et al., 2012; Lambourne & Tomporowski, 2010), CRT (Chang et al., 2012; Tomporowski, 2003), verbal working memory (Lambourne & Tomporowski, 2010), visual memory (Chang et al., 2012). According to Chang et al. (2012), verbal/word fluency gains a substantial definite improvement. When visual memory is mediated by verbal coding, as in reading and spelling (Giles & Terrell, 1997), verbal IQ which is primarily involved in information analysis and language processing becomes relevant to ensuring participants’ aptitude levels are generally consistent – to gain entry to university, all participants must have demonstrated a set aptitude level. As outlined by Audriffen and André (2015), light intensity, short duration PE only places a light load on the global/local task switching component of EF. The mode of PE used for this experiment, air-cycling is a steady-state, aerobic activity which has been shown to be beneficial to CP (Chang et al., 2012; Lambourne & Tomporowski, 2010). The antecedent high-resolution analysis of the literature supports the hypotheses that two small increments of improvement in CP from the groups that performed PE as compared with the group that did not.
The rudimentary design of this experiment makes it susceptible to flaws that negatively affect the integrity of results. Generally, the design of the experiment is low-resolution – the participants’ physical condition was not assessed, nor were the groups balanced for age and sex, and each tutorial group conducted the experiment at different times of the day.
While the results of this experiment contribute to the expanding corpus on the topic, the limitations described adversely affect implications that might be drawn from the results. However, at the general level, the results suggest that minimal PE can have an overall positive effect on CP. More rigorously designed experiments that test the effect of mild arousal on CP should be performed to improve the integrity of the results.
References
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