Constrained paths based on the Farey sequence in learning to juggle

In this article we report the results of a study conducted to investigate the learning dynamics of three-ball juggling from the perspective of frequency locking. Based on the Farey sequence, we predicted that four stable coordination patterns, corresponding to dwell ratios of 0.83, 0.75, 0.67, and 0.50, would appear in the learning process. We examined the learning process in terms of task performance, taking into account individual differences in the amount of learning. We observed that the participants acquired individual-specific coordination patterns in a relatively early stage of learning, and that those coordination patterns were preserved in subsequent learning, even though performance in terms of number of successful consecutive throws increased substantially. This increase appeared to be related to a reduction in spatial variability of the juggling movements. Finally, the observed coordination patterns were in agreement with the predicted patterns, with the proviso that the pattern corresponding to a dwell ratio of 0.50 was not realized and only a hint of evidence was found for the dwell ratio of 0.67. This implies that the dwell ratios of 0.83 and 0.75 in particular exhibited a stable coordination structure due to strong frequency locking between the temporal variables of juggling.     

Perceiving red decreases motor performance over time: A pilot study

IntroductionColors may influence motor performance.ObjectiveThe present study aimed to compare the effects of perception of red and green environments on physical (performance and heart rate) and psychological (perceived effort, anxiety and enjoyment) parameters during cycling trials.MethodTen cyclists achieved two identical series of three randomized 7-minute trials on home trainers, during which they were continuously exposed to red, green, and gray environments. Covered distance and heart rate were recorded during each trial, after which participants answered items intended to assess perceived effort, anxiety, and enjoyment experienced during the trial.ResultsResults showed that covered distance (ps ≤ .02) and heart rate (ps ≤ .03) were lower in the red environment than in the gray and green environments. Enjoyment was higher in the green environment than in the red environment (p = .006). The colored environments did not influence perceived effort and anxiety (ps > .05).ConclusionThis study is the first to show that perceiving red is detrimental for motor performance over an extended period of time.     

Emergent Power Hierarchies and Group Performance

In newly formed groups, informal hierarchies emerge automatically and readily. In this study, we argue that emergent group hierarchies enhance group performance (Hypothesis 1) and we assume that the more the power hierarchy within a group corresponds to the task‐competence differences of the individual group members, the better the group performs (Hypothesis 2). Twelve three‐person groups and 28 four‐person groups were investigated while solving the Winter Survival Task. Results show that emerging power hierarchies positively impact group performance but the alignment between task‐competence and power hierarchy did not affect group performance. Thus, emergent power hierarchies are beneficial for group performance and although they were on average created around individual group members' competence, this correspondence was not a prerequisite for better group performance.     

The role of perceptual similarity of the task environments in children’s perseverative responding

Perseverative responding is often seen in children’s performance in a variety of contexts. One such context is symbolic comprehension in which 2- and 2½-year-olds demonstrate difficulty in appreciating the association of symbols (pictures and scale models) and their referents and show a high proportion of perseverative responding. Representational-level explanations of perseveration were explored in the current studies via examination of the impact of perceptual similarity of visual environments across trials. Across two experiments, children saw either a picture (Experiment 1) or a scale model (Experiment 2) of a hiding location of a room and were then encouraged to recover the toy from an identical room. Manipulating the perceptual similarity of the environments across successive trials affected performance and perseverative responding. These results highlight the critical role played by perceptual information not only in symbolic tasks but also in many other tasks and have important implications for theories of perseveration.     

A validation of a computerised task of risk-taking and moral decision-making and its association with sensation-seeking,impulsivity and sociomoral reasoning

The aim of this study was to investigate the reliability and validity of the computer based application of the Secret Agent (SA) task of risk-taking and moral decision-making. The participants were 100 male patients in a maximum security hospital (50 with severe mental illness and 50 with personality disorder) and 50 community based healthy controls. All participants completed the SA task, the Iowa Gambling Task (IGT), and measures of IQ, antisocial personality traits, sensation-seeking, impulsivity and sociomoral reasoning. The SA risk-taking and moral decision-making scales had satisfactory levels of reliability (Cronbach’s alpha). Risk-taking correlated significantly with sensation-seeking across all three participant groups. In contrast, risk-taking only correlated with impulsivity among the severe mental illness group. Moral decision-making correlated with sociomoral reasoning among the personality disorder group. No correlation was found between the SA scores and the IGT score and the IGT did not correlate with sensation-seeking or impulsivity. IQ and antisocial personality traits did not correlate with the SA or IGT scales. The study highlights the importance of context, the nature of the risk-taking task, and ‘problem framing’ of the instructions in their relationship with individual differences.     

Positive affect facilitates task switching in the dimensional change card sort task: Implications for the shifting aspect of executive function

Using the modified Dimensional Change Card Sort task, we examined the influence of positive affect on task switching by inspecting various markers for the costs, including restart cost, switch cost and mixing cost. Given that the executive-control processes that underlie switching performance—i.e., inhibition or shifting—are distinct from the component processes that underlie non-switching performance—i.e., stimulus evaluation, resource allocation or response execution—we hypothesised that if positive affect facilitates task switching via executive-control processes, rather than via component processes, positive affect would reduce both switch and restart costs, but not mixing cost, because both switch and restart costs rely on executive processes, while mixing cost imposes only minimal demands on executive processes. We found beneficial effects of positive affect on both restart and switch costs, but not on mixing costs. These results suggest that positive affect improves switching abilities via executive processes rather than via component processes.     

When emotion does and does not impair performance: A Garner theory of the emotional Stroop effect

It takes people longer to name the ink colour of emotion or threat words than that of neutral words, the emotional Stroop effect (ESE). In three experiments with normal and patient populations, we show that the ESE is a special case of a generic attention model and effect entailed in Garner's speeded classification paradigm. Guided by the Garner model we demonstrate that task-irrelevant dimensions that differ in salience can produce the ESE and mimic it with neutral stimuli. When each word appears in a constant colour, as mandated in the correlation condition of the Garner design, the ESE is eliminated. This important result is consistent with the attention account of the ESE. We conclude that when emotion stimuli appear in a random fashion they interfere with task performance. However, when emotion stimuli are correlated with features of the ongoing task they help task performance not least due to their extreme salience.     

Task conflict,information processing,and decision-making: The damaging effect of relationship conflict

A popular theoretical assumption holds that task-related disagreements stimulate critical thinking, and thus may improve group decision making. Two recent meta-analyses showed, however, that task conflict can have a positive effect, a negative effect, or no effect at all on decision-making quality (De Dreu & Weingart, 2003; De Wit, Greer, & Jehn, 2012). In two studies, we built upon the suggestion of both meta-analyses that the presence of relationship conflict determines whether a task conflict is positively or negatively related to decision making. We hypothesized and found that the level of perceived relationship conflict during task conflict (Study 1), and the actual presence (vs. absence) of relationship conflict during task conflict (Study 2), increased group members’ rigidity in holding onto suboptimal initial preferences during decision making and thus led to poor decisions. In both studies the effect of relationship conflict on decision making was mediated by biased use of information.     

Developmental changes of win-stay and loss-shift strategies in decision making

This study aims to clarify the developmental changes in real-life decision making when strategy is adjusted using both positive and negative feedback, that is, whether strategic adjustment evolves with age. A total of 84 participants divided into three age groups (children, adolescents, and adults) performed the standard version of the Iowa Gambling Task (IGT). Children and adolescents showed a strong bias in favor of disadvantageous choices whereas adults learned to decide advantageously during the course of the task. Interestingly, the results clearly demonstrate that children did not switch differently following gains and losses whereas adolescents and adults switched more often after a loss than after a gain, corresponding to the “loss-shift” and the “win-stay” strategies, respectively. The results also revealed that adults switched less often after losses compared to children and adolescents and, thus, used the loss-stay strategy more often than the 2 youngest groups. These new findings suggest that successful completion of the IGT by adults requires fine feedback monitoring and more frequent use of the win-stay and loss-stay strategic adjustments.