1. Introduction
A critical factor for performance in many sports is the ability to react quickly to an external stimulus. For example, to perform an effective tackle, a defender in soccer must be able to react quickly to the abrupt movement of the opponent. Similarly, a basketball player must respond quickly to the trajectory of the ball to collect a rebound, and so must a volleyball player to recover a ball that is deflected off a block. Thus, in addition to improving physical condition, athletes and their coaches often place much emphasis during training on improving reaction speed to stimuli [
1].
Drills aiming to improve reaction speed typically involve presenting abrupt stimuli (e.g., light, sound, movement) to which the athlete is called to react as fast as possible. For example, in whole-body reactive agility tests, the athlete starts running in a specific direction (e.g., forward) and is asked to change direction to the left or the right in response to the location of a sound or a signal from the coach [
2,
3]. Similarly, in light training tasks, such as the Batak Pro, the Fitlight Trainer system, and SpeedPad, the athlete is called to hit, as fast as possible, targets that light up or change color. Notably, several studies have documented improvements in motor reaction time following training with light training tasks. For example, ref. [
4] showed improvements in upper and lower limb reaction times in basketball players following an 8-week training program with the Fitlight Trainer system (see also [
5] for similar results with junior players of handball, basketball, and volleyball). Also, ref. [
6] showed that basketball players training with Fitlight exhibited greater improvements in dribbling skill and hand reaction than players who completed a similar program without Fitlight training.
In addition, past studies indicate that light training systems and reactive agility tasks with whole-body movement have discriminatory power. For example, ref. [
7] showed that handball players had significantly faster reaction times using the Fitlight Trainer than non-athlete controls when carrying out exercises with lights that were placed horizontally in front of them. Also, ref. [
8] showed that the extent of engagement in physical activity predicted reaction times in both a simple version of Fitlight that involved responding to target lights with the dominant hand and a complex version that entailed responding with one or the other hand depending on the color of the target light.
In summary, past research documents that (1) athletes have better performance in reactive agility tasks than controls and that (2) training with such tasks improves motor reactions times in the same task used for training [
4] or different tasks that involve fast reactions to stimuli [
6]. Despite these findings, it is not entirely clear yet what drives either the individual differences in reaction time or the training gains that past studies report. That is, although performance in tasks like this is very likely influenced by physical attributes and neuromuscular efficiency (e.g., balance and stability, motor control, elastic strength), it may also depend on cognitive factors, such as attention, perception, and decision making. Thus, individual differences and/or benefits in motor reaction times might be caused by improvements in physical skill, cognitive factors, or both.
To address the extent to which cognitive factors are involved in carrying out reactive agility tasks, in the current study we examined the discriminatory power of SpeedPad, a flexible light training app that leverages Mixed Reality technology by comparing the performance of participants engaged in physical exercise with that of participants who are not; at the same time, we evaluated participants’ cognitive functioning through traditional cognitive tests. Specifically, we examined whether different attentional processes account for variability in SpeedPad performance.
This study builds upon previous research from our group [
9] showing the individual differences in performance on SpeedPad are predicted by attentional orienting (i.e., the ability to orient attention quickly towards stimuli in response to cues) and by split attention (i.e., the ability to divide attention across locations). These findings, along with those from other studies that administered light training tasks along with cognitive tasks such as the D2 Attention Test [
8] and the flanker task [
9], suggest that the efficient deployment of attention is critical for high performance in these training tasks. Given that attention is multifaceted, the present study extends the literature by assessing different attentional processes to those studied before, addressing at the same time limitations in past research. For example, in the study of [
10], SpeedPad performance was predicted by reaction time in a Posner cueing task but not by the cueing effect (valid–invalid RT difference). This suggests SpeedPad captures attentional orienting speed but not the ability to strategically use cues. A limitation was that the cuing task used measured top-down (endogenous) orienting, whereas SpeedPad likely relies more on automatic, bottom-up (exogenous) attention. Similarly, visual search efficiency also correlated with SpeedPad but did not explain unique variance. However, the visual search task used conjunction search, which is effortful and serial, unlike SpeedPad’s pop-out (feature search) demands.
Thus, in the current study, we used an exogenous cueing task, included both feature and conjunction search trials, added distractor lights in SpeedPad, and increased sample size to better test group differences. This allowed us to explore through regression analyses whether the automatic orienting of attention and the efficiency of searching for a target among distractors would explain individual differences in SpeedPad performance. In addition, we further examined individual differences in SpeedPad performance and cognitive function by dividing participants in two groups: those who reported engagement in physical activity vs. those who did not.
Our main prediction, based on the findings of [
7] and Reigal et al. [
8], was that participants who engage in exercise would demonstrate better performance in SpeedPad. Based on past studies documenting the involvement of cognitive skills in sports (e.g., [
11]; for reviews on the topic see also [
12,
13]), we also expected participants who engaged in physical activity to outperform those who did not in the two attentional tasks (exogenous cueing, visual search) as well. We also hypothesized that participants with faster attentional orienting in response to cueing would perform better on a simple scenario of SpeedPad without distractors, clearly implicating exogenous attentional capture. Of interest was to see whether this would also be the case in a more complex scenario of SpeedPad, which requires filtering out distractors and might thus implicate top-down processes such as serial visual search. Therefore, we also expected visual search efficiency in the conjunction search trials to predict individual differences in the complex scenario of SpeedPad that involved distractors but not in the simple scenario. Of interest was to examine whether attentional orienting and visual search would explain unique variance in SpeedPad performance beyond that explained by engagement in physical activity. Such a result would provide convincing evidence that light training tasks such as SpeedPad rely, in addition to physical skills, on cognitive functions as well.
Identifying the specific cognitive abilities engaged during light training tasks such as SpeedPad will help determine whether these tasks can produce transferable training benefits for athletic activities in which those cognitive abilities are critical. This long-term objective is motivated by the growing evidence showing that immersive VR training tasks that engage cognitive processes can lead to both short- and long-term cognitive benefits (e.g., [
14,
15]).
3. Statistical Analyses
First, we examined whether the cueing task and the visual search tasks produced the pattern of results expected in the literature, and then we carried out analyses to determine performance differences across participants who exercised vs. those who did not.
For the cueing task, we used a t-test to examine whether responses were faster for valid compared to invalid trials, yielding the expected cueing benefit. To examine whether there were differences in reaction times for valid and invalid trials across the exercise and non-exercise groups, we then conducted a repeated-measures Analysis of Variance (ANOVA) with Trial Type (Valid vs. Invalid Trials) as a within-participants variable and Group (Exercise vs. Non-Exercise) as the between-participants variable.
To verify that the visual search task we used replicated the expected pattern of results documented in the literature, we carried out a repeated-measures ANOVA with terms for Search Type (Feature search vs. Conjunction search) and Set Size (1, 5, 15) for the participants’ reaction times (RTs). Then, we used a custom script in R to compute the RT x set size function and extract each participant’s intercept and slope values. Intercept values index participants’ baseline processing speed, which is essentially the time it takes them to make a decision while unaffected by distractors. Slope values index the effect of each distractor in the display on participants’ search speed. Thus, a small slope value translates to high search efficiency as it indicates that the participants were not greatly influenced by the distractors. In contrast, large slope values index low search efficiency, as they indicate a large effect of distractors on search speed. Following this computation, we carried out separate repeated-measures ANOVAs to compare intercepts and slopes for feature and conjunction search trials between the exercise and the non-exercise groups.
For SpeedPad, we carried out a repeated-measures ANOVA on the number of hits with terms for Scenario Type (Simple vs. Complex) and Group (Exercise vs. Non-Exercise).
We followed-up the measure-specific analyses with correlational analyses to investigate possible relations between the computerized tasks and SpeedPad. Finally, to investigate whether individual differences in SpeedPad could be explained by our cognitive measures, we performed a hierarchical linear regression for each of the Simple and the Complex sessions of SpeedPad, using the engagement in physical exercise and one RT measure from each of the computerized tasks as predictors. Based on observation of the simple correlations, we selected the cueing benefit and the intercept value of feature search trials as predictors.
5. Discussion
The present study aimed to assess the discriminatory power of light training tasks and investigate the attentional subprocesses they rely on. In respect to discriminatory power, we found that participants who reported current and past engagement in sports and dancing activities outperformed those who did not in both the simple and the complex scenarios of SpeedPad. This finding is aligned with the finding of [
7] that handball players do better than controls in light training tasks, as well as with the results of [
8], showing that engagement in physical activity predicts performance.
In addition, participants who reported engagement in physical activity were faster than those who did not in the exogenous cueing task in trials with both valid and invalid cues. Given the automatic nature of this task, this finding suggests that participants engaged in physical activity had sharper reflexes, orienting their attention faster towards a validly cued location. Notably, that the advantage was present in invalid trials as well indicates that they were also more efficient in turning their attention away from a location that provides no benefit. Thus, our findings with the cueing task document that participants engaged in exercise had a more efficient attentional disengagement and re-orienting allocation mechanism were in line with the findings of [
10], which used endogenous orienting.
The advantage of participants reporting engagement in physical activity in both SpeedPad and the exogenous cueing task is in line with the conclusions of the meta-analyses of [
12] and [
13]: that performance in cognitive tests varies with sport expertise. First, ref. [
12] reported a small-to-medium-sized effect for the overall athlete effect, with athletes performing better than controls in measures of processing speed and some types of attention. Then, ref. [
13] reported a medium effect size for the difference between overall cognitive function and skills between higher and lower-skilled athletes. Notably, the effects were larger for tasks that used sport-specific stimuli compared to general stimuli. Despite both SpeedPad and the exogenous cueing task using general stimuli and our sample not including professional athletes, we found significant effects of engagement in physical activity. The difference being present in the cueing task, a task that does not require much physical effort, suggests that the advantage of participants reporting engagement in physical activity was cognitive or in addition to physical.
Importantly, the efficiency of the attentional orienting system, as indexed by the cueing benefit in this task, was a significant predictor of SpeedPad performance over and above physical engagement. Thus, overall, our results suggest that athletes may have more advanced attentional control (including attentional orienting, disengagement, and re-allocation of attention), a cognitive mechanism that underlies performance in SpeedPad along with other attributes that may develop from physical engagement, e.g., physical endurance. As in this study we did not measure any physical attributes, it remains to be seen in future research what these attributes are.
In addition to attentional orienting, we expected participants who engaged in physical activities to also have more advanced visual search skills and that these skills would also predict SpeedPad performance. Our findings did not provide evidence of that. First, in both feature and conjunction search trials, participants engaged in exercise had similar performance to those who did not. Second, the slope of the visual search functions did not correlate with SpeedPad performance. That said, the intercept in the visual search functions did correlate with SpeedPad performance and also predicted unique variance in performance over and above engagement in physical activity and attentional control. However, the intercept in visual search indexes the time required to detect a stimulus in the absence of distractors. Thus, it can be regarded more as an index of detection speed rather than an index of visual search capacity.
Taken together, our findings from the two tasks indicate that SpeedPad relies on three cognitive factors: the ability to detect information quickly, the ability to orient attention reflexively to a location in space, and the ability to disengage attention and quickly re-orient to a new location, after it has been reflectively directed to a location in space. Current results also indicate that people engaged in physical activities may have more-developed orienting and re-orienting abilities than those who do not exercise.
The finding of a group effect in SpeedPad and the cueing task but not in the visual search task is intriguing. One possible explanation relates to the different demands of the tasks. While SpeedPad and the cueing task entail the anticipation of targets that appear suddenly, visual search is more about scanning the visual field for a target that is already there. Although scanning is a common activity in many sports, it may rely on core cognitive processes that do not develop much with practice. Indeed, past studies document that although overall reaction time in visual search tasks can be reduced with practice, the set-size slopes indexing search efficiency do not change [
20,
21]). Perhaps then, our participants who carried out 288 trials of visual search had adequate practice to reach their maximum search speed, masking any initial differences from sport engagement.
In the context of sports, past research suggests that in terms of visual search behaviors, athletes and non-athletes differ qualitatively rather than quantitatively. For example, a meta-analysis by [
22] concluded that, in sport-specific visual search tasks, athletes carry out fewer but longer fixations, as well as longer quiet eye periods, indicative of more efficient visual information sampling. The same meta-analysis concluded that differences in reaction times between athletes and non-athletes are generally small and inconsistent and that athlete advantages are primarily linked to anticipation (see also [
23,
24] for empirical evidence). The involvement or not of anticipation could explain why in the present study we found group differences in the SpeedPad and the cueing task but not in the visual search task. That said, it should be noted that the intercept of the visual search function correlated negatively with SpeedPad performance and contributed unique variance in the regression analyses. Our conjecture is that these results reflected general processing speed rather than visual search efficiency.
Overall, our findings complement past studies aiming to understand the cognitive processes that underlie light training and reactive agility tasks in general. In our view, this knowledge is essential for understanding what drives the improvements that are documented in these tasks. For example, as noted in the Introduction, ref. [
6] showed that basketball players training with Fitlight exhibited greater improvements in dribbling skill and hand reaction than players who completed a similar program without Fitlight training. Yet, it is not clear what drove these gains. Was it an improvement in physical skills such as motor control or elastic strength that led to better dribbling skill and shorter hand reaction time? Or was it an improvement in cognitive processes such as attentional control that allowed participants to orient and re-orient their attention more efficiently? While our findings cannot speak about the real cause of the improvement reported in [
6] or other similar studies (e.g., [
4]), they do suggest that improvement may indeed be due, at least partly, to cognitive factors relating to attention and overall processing speed. Future training studies with such reactive agility tasks, looking also at how perception and attention might change with training, might shed more light on this topic.
Obtaining a nuanced understanding about cognitive processes that underlie light training and reactive agility tasks will allow using these tools in a more targeted and personalized manner by athletes and their coaches. For example, knowing that light training tasks such as those in SpeedPad rely on the fast detection of target stimuli and on the efficient attentional orienting subprocesses allows one to use the task more confidently with athletes whose sport or position involves these cognitive processes. For example, SpeedPad seems more suitable for a soccer goalkeeper whose main job is to anticipate and react to shots than a midfielder whose job may rely more heavily on other processes such as visual search.
Thus, in our view, effective cognitive training tasks must engage the same cognitive processes required by the target activity. Previous research using immersive VR has produced promising findings when training interventions closely matched the cognitive demands of the outcome measures. For example, a randomized controlled trial with e-sport athletes by [
14] found that training with Beat Saber, an immersive VR rhythm game in which players use sabers to slash colored blocks synchronized with music, improved performance on measures of concentration and alternating attention. These benefits likely emerged because the game places high demands on sustained focus and rapid attentional switching, requiring players to continuously identify block colors and respond with the corresponding saber under time pressure.
Although our study provides important new insights about light training tasks, we must acknowledge two important limitations regarding our sample. First, the study recruited participants who engaged in physical activity, a selection criterion that was defined rather loosely as “any type of physical activity undertaken currently or in the near past”. As a result, we ultimately had a diverse experimental group that included participants engaging in different sports as well as dancing, for various periods of time. While this was done on purpose to avoid focusing the study on a particular sport and expertise level, this means that we grouped together participants engaging in activities that may differ substantially in terms of attentional and perceptual demands as well as in spatial ability, e.g., dancing vs. martial arts. Thus, it is highly important that future studies investigate more uniform groups (e.g., soccer players) or even specific sub-groups (e.g., soccer goalkeepers). Of interest would be the examination of whether light training tasks can discriminate not just athletes from non-athletes but also athletes in the same sport but at different levels of expertise, e.g., elite vs. amateur soccer players. Second, the majority of our participants were female, with only 10 male participants included in the sample. Although this differs from much of the existing sports literature, which has historically focused predominantly on male athletes, we believe this represents an important and underrepresented perspective in the field. At the same time, the gender distribution of our sample may limit the generalizability of the findings across broader athletic populations. Importantly, however, including gender as a factor in our statistical analyses did not meaningfully alter the overall pattern of results, suggesting that the observed effects were relatively robust across male and female participants. Another limitation of the current study is that we did not assess any variables related to motor control that could account for individual differences in SpeedPad performance. Future studies may explore whether variables related to online motor control efficiency and stability (e.g., jerk) may explain additional variance in reactive agility tests tasks.
Despite these limitations, the current findings further our knowledge about the role of cognition in light training tasks that are commonly used by athletes in various sports despite the limited knowledge we have about of what they train. Specifically, our results indicate that good performance in light training tasks such as SpeedPad requires fast stimulus detection and efficient control of attention. As both skills are important in various sports, our results align with the past literature, suggesting that light training tasks could potentially be useful tools for exercising aspects of attention and improving processing speed in athletes. The current findings may also help explain why SpeedPad performance has previously been shown to correlate with performance in a virtual goalkeeping task [
25]. Presumably, similar to SpeedPad, successful shot-blocking as a goalkeeper relies on rapid stimulus detection and efficient attentional control.
Coupled with the findings of [
10], the results from the present study provide a clearer picture about the cognitive processes that underlie light training tasks. These results can serve as the basis for new intervention studies with light training that will target processes and tasks that rely on the control of attention. Although a few past studies have already used light training as an intervention with positive results (e.g., [
4,
5,
6]), it is yet not clear how exactly the benefits came about. To this end, our findings may offer some insights. For example, in the studies by [
4,
5,
6], the benefits were present in outcome measures that required the fast orienting of attention to target stimuli. Based on the current findings, we may posit that Fitlight training in these studies boosted attentional orienting abilities. More importantly, our findings may explain the lack of benefits reported in other studies. For example, ref. [
26] found no differences in cognitive function and physical fitness between a group of male soccer players aged 10–15 that trained with Fitlight vs. a control group. Notably, in this study cognitive function was assessed using a Figure Drawing test and a Pen-to-Point test. Neither of these tests involves attentional control. In sum, our findings suggest that future studies using light training tasks as interventions should look for training benefits in tasks that rely heavily on the fast orienting of attention to stimuli.