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Creativity, specifically divergent thinking, has been shown to benefit from unrestrained walking. Despite these findings, it is not clear if it is the lack of restriction that leads to the improvement. Our goal was to explore the effects of motor restrictions on divergent thinking for different movement states. In addition, we assessed whether spontaneous eye blinks, which are linked to motor execution, also predict performance. In experiment 1, we compared the performance in Guilford's alternate uses task (AUT) during walking vs. sitting, and analysed eye blink rates during both conditions. We found that AUT scores were higher during walking than sitting. Albeit eye blinks differed significantly between movement conditions (walking vs. sitting) and task phase (baseline vs. thinking vs. responding), they did not correlate with task performance. In experiment 2 and 3, participants either walked freely or in a restricted path, or sat freely or fixated on a screen. When the factor restriction was explicitly modulated, the effect of walking was reduced, while restriction showed a significant influence on the fluency scores. Importantly, we found a significant correlation between the rate of eye blinks and creativity scores between subjects, depending on the restriction condition. Our study shows a movement state-independent effect of restriction on divergent thinking. In other words, similar to unrestrained walking, unrestrained sitting also improves divergent thinking. Importantly, we discuss a mechanistic explanation of the effect of restriction on divergent thinking based on the increased size of the focus of attention and the consequent bias towards flexibility.
In this work, we evaluate the status of both theory and empirical evidence in the field of experimental rest-break research based on a framework that combines mental-chronometry and psychometric-measurement theory. To this end, we (1) provide a taxonomy of rest breaks according to which empirical studies can be classified (e.g., by differentiating between long, short, and micro-rest breaks based on context and temporal properties). Then, we (2) evaluate the theorizing in both the basic and applied fields of research and explain how popular concepts (e.g., ego depletion model, opportunity cost theory, attention restoration theory, action readiness, etc.) relate to each other in contemporary theoretical debates. Here, we highlight differences between all these models in the light of two symbolic categories, termed the resource-based and satiation-based model, including aspects related to the dynamics and the control (strategic or non-strategic) mechanisms at work. Based on a critical assessment of existing methodological and theoretical approaches, we finally (3) provide a set of guidelines for both theory building and future empirical approaches to the experimental study of rest breaks. We conclude that a psychometrically advanced and theoretically focused research of rest and recovery has the potential to finally provide a sound scientific basis to eventually mitigate the adverse effects of ever increasing task demands on performance and well-being in a multitasking world at work and leisure.
The Role of Blinks, Microsaccades and their Retinal Consequences in Bistable Motion Perception
(2021)
Eye-related movements such as blinks and microsaccades are modulated during bistable perceptual tasks. However, if they play an active role during internal perceptual switches is not known. We conducted two experiments involving an ambiguous plaid stimulus, wherein participants were asked to continuously report their percept, which could consist of either unidirectional coherent or bidirectional component movement. Our main results show that blinks and microsaccades did not facilitate perceptual switches. On the contrary, a reduction in eye movements preceded the perceptual switch. Blanks, on the other hand, thought to mimic the retinal consequences of a blink, consistently led to a switch. Through the timing of the blank-introduced perceptual change, we were able to estimate the delay between the internal switch and the response. This delay further allowed us to evaluate that the reduction in blink probability co-occurred with the internal perceptual switch. Additionally, our results indicate that distinct internal processes underlie the switch to coherent vs. component percept. Blanks exclusively facilitated a switch to the coherent percept, and only the switch to coherent percept was followed by an increase in blink rate. In a second study, we largely replicated the findings and included a microsaccade analysis. Microsaccades only showed a weak relation with perceptual switches, but their direction was correlated with the perceived motion direction. Nevertheless, our data suggests an interaction between microsaccades and blinks by showing that microsaccades were differently modulated around blinks compared with blanks. This study shows that a reduction in eye movements precedes internal perceptual switches indicating that the rate of blinks can set the stage for a reinterpretation of sensory input. While a perceptual switch based on changed sensory input usually leads to an increase in blink rate, such an increase was only present after the perceptual switch to coherent motion but absent after the switch to component percept. This provides evidence of different underlying mechanism or internal consequence of the two perceptual switches and suggests that blinks can uncover differences in internal percept-related processes that are not evident from the percept itself.
Pupil dilation is known to be affected by a variety of factors, including physical (e.g., light) and cognitive sources of influence (e.g., mental load due to working memory demands, stimulus/response competition etc.). In the present experiment, we tested the extent to which vocal demands (speaking) can affect pupil dilation. Based on corresponding preliminary evidence found in a reanalysis of an existing data set from our lab, we setup a new experiment that systematically investigated vocal response‐related effects compared to mere jaw/lip movement and button press responses. Conditions changed on a trial‐by‐trial basis while participants were instructed to keep fixating a central cross on a screen throughout. In line with our prediction (and previous observation), speaking caused the pupils to dilate strongest, followed by nonvocal movements and finally a baseline condition without any vocal or muscular demands. An additional analysis of blink rates showed no difference in blink frequency between vocal and baseline conditions, but different blink dynamics. Finally, simultaneously recorded electromyographic activity showed that muscle activity may contribute to some (but not all) aspects of the observed effects on pupil size. The results are discussed in the context of other recent research indicating effects of perceived (instead of executed) vocal action on pupil dynamics.
Animals, just like humans, can freely move. They do so for various important reasons, such as finding food and escaping predators. Observing these behaviors can inform us about the underlying cognitive processes. In addition, while humans can convey complicated information easily through speaking, animals need to move their bodies to communicate. This has prompted many creative solutions by animal neuroscientists to enable studying the brain during movement. In this review, we first summarize how animal researchers record from the brain while an animal is moving, by describing the most common neural recording techniques in animals and how they were adapted to record during movement. We further discuss the challenge of controlling or monitoring sensory input during free movement.
However, not only is free movement a necessity to reflect the outcome of certain internal cognitive processes in animals, it is also a fascinating field of research since certain crucial behavioral patterns can only be observed and studied during free movement. Therefore, in a second part of the review, we focus on some key findings in animal research that specifically address the interaction between free movement and brain activity. First, focusing on walking as a fundamental form of free movement, we discuss how important such intentional movements are for understanding processes as diverse as spatial navigation, active sensing, and complex motor planning. Second, we propose the idea of regarding free movement as the expression of a behavioral state. This view can help to understand the general influence of movement on brain function.
Together, the technological advancements towards recording from the brain during movement, and the scientific questions asked about the brain engaged in movement, make animal research highly valuable to research into the human “moving brain”.
Sensory input as well as cognitive factors can drive the modulation of blinking. Our aim was to dissociate sensory driven bottom-up from cognitive top-down influences on blinking behavior and compare these influences between the auditory and the visual domain.
Using an oddball paradigm, we found a significant pre-stimulus decrease in blink probability for visual input compared to auditory input. Sensory input further led to an early post-stimulus blink increase in both modalities if a task demanded attention to the input. Only visual input caused a pronounced early increase without a task. In case of a target or the omission of a stimulus (as compared to standard input), an additional late increase in blink rate was found in the auditory and visual domain. This suggests that blink modulation must be based on the interpretation of the input, but does not need any sensory input at all to occur.
Our results show a complex modulation of blinking based on top-down factors such as prediction and attention in addition to sensory-based influences. The magnitude of the modulation is mainly influenced by general attentional demands, while the latency of this modulation allows to dissociate general from specific top-down influences that are independent of the sensory domain.
The latency of spontaneous eye blinks marks relevant visual and auditory information processing
(2021)
Eye blinks are influenced by external sensory and internal cognitive factors, as mainly shown in the visual domain. In previous studies, these factors corresponded to the time period of task-relevant sensory information and were often linked to a motor response. Our aim was to dissociate the influence of overall sensory input duration, task-relevant information duration, and the motor response to further understand how the temporal modulation of blinks compares among sensory modalities.
Using a visual and an auditory temporal judgment task, we found that blinks were suppressed during stimulus presentation in both domains and that the overall input length had a significant positive relationship with the length of this suppression (i.e., with the latency of the first blink after stimulus onset). Importantly, excluding the influence of the overall sensory input duration we could show that the duration of task-relevant input had an additional influence on blink latency in the visual and the auditory domain. Our findings further suggest that this influence was not based on sensory input but on top–down processes. We could exclude task difficulty and the timing of the motor response as driving factors in the blink modulation.
Our results suggest a sensory domain–independent modulation of blink latencies, introduced by changes in the length of the task-relevant, attended period. Therefore, not only do blinks mark the timing of sensory input or the preparation of the motor output, but they can also act as precise indicators of periods of cognitive processing.