It is well-documented that emotional stimuli impact both the cognitive and motor aspects of “goal-directed” behavior (Beatty et al., 2016; Lu et al., 2017). In particular, emotional distracters impact ongoing cognitive processes (Dolcos and McCarthy, 2006). In our daily life, emotional distraction is particularly disruptive to goal-directed behavior. Processing these task-irrelevant emotional stimuli interferes with the performance of a cognitive performance, including working memory and visual searches (Dolcos et al., 2006; Pedale et al., 2019). Distracting emotions might capture attention and reallocate resources used for processing (Ellis and Ashbrook, 1988), consequently impairing cognitive performance. However, how distracting emotions impact motor performance remains unclear. In addition, emotions might influence motor performance differently depending on the type of movement (Jasinska et al., 2012; Gorniak, 2019). For example, when an individual is scared by a spider, it might impact their movement when they were moving a mug from one side of their body to the other. However, this emotional effect would vary depending on the complexity of the moving task. For instance, the emotional effect is typically lower when sliding a mug directly across a desk compared to lifting it above many objects on a desk. Thus, we speculated that the effects of distracting emotions on motor performance could be modulated by the complexity of the movement.

Previous studies examined how emotional stimuli impact motor performance. For example, compared to neutral stimuli, negative emotional stimuli elicit a faster pushing movement (i.e., avoidance), whereas positive images accelerate pulling speed (i.e., approach; Krieglmeyer et al., 2010; Boyd et al., 2011; Önal-Hartmann et al., 2012; Deuter et al., 2014; Hans Phaf et al., 2014). Compared to the speed and the force of movement (Coombes et al., 2006), the precision of movement has received less attention. Emotional stimuli could be either the current target being searched for or task-irrelevant distractors. The impact of “emotional distraction” on goal-directed behavior has been primarily studied in the context of several cognitive behaviors. For example, during the phase of maintaining working memory, the presentation of negative stimuli evokes increased activity in emotional-related areas and decreased activation in working memory-related areas (Dolcos and McCarthy, 2006). Through evaluating stimuli embedded within complex everyday scenes, Pedale et al. (2019) showed that emotional distractors are fixated later, and for a shorter duration, compared to emotional targets, indicating efficient top-down control in avoiding emotional distraction. As such, task-irrelevant emotional distractors might capture attention and impair the performance of on-going motor tasks. Yet, studies investigating how emotional distraction impacts behavior with respect to movement/motion remains limited. Thus, motor performance needs to be evaluated with kinematic measurements to bridge gaps between distracting emotions and motor performance.

The duration of exposure to emotional stimuli impacts the speed and accuracy of movement in different ways (Coombes et al., 2005). In a square-tracing task, the length of exposure to affective stimuli mediates the speed and accuracy of motor performance. Within this task, compared with positive stimuli, negative stimuli led to either increased error (short exposure) or increased speed (multiple exposures). Thus, emotional effects depend the moment in time a given task needs processing resources. Consequently, chronometry measurements could provide valuable insights on the perception of emotion during the execution of movement. As such, it is important to distinguish between and account for the fundamental aspects of movement, which are divided into a premotor phase (from the presentation of a stimulus to the initiation of movement) and an execution phase (from the initiation of movement to the completion of movement; Krakauer et al., 2019). Studies using chronometric measurements and divided response times (reaction time and movement time), previous studies showed that only the reaction time (time from stimulus presentation to initiation of the movement response) is impacted by the presentation of an emotional stimulus (Lu et al., 2017). Compared to the button-pressing task used by Lu et al. (2017), a more complex or more ecological valid motor task is needed to investigate how emotions impact different phases of movement.

Movement complexity is regarded as an important factor influencing the quality of movement. We previously showed that when using “release-move-press” movement (rather than “press only” movement), more complex behavior requires more attention during performance, and that, as behavior becomes more complex, emotional processes impact the quality of movement more (Lu et al., 2017). Thus, different aspects of motor performance are likely impacted by the interaction between the valence of distracting emotions with movement complexity. However, it is not known whether the complex level of movement heterogeneously impacts the quality of motor performance.

Accuracy is usually calculated as the percentage of correct responses when evaluating the quality of cognitive-motor performance. Measurements estimating the quality of movement (e.g., root-mean-squared-error, RMSE) are typically used to assess cognitive-motor tasks (Franks et al., 1982; Coombes et al., 2008; Gentili et al., 2011). Thus, RMSE might provide a rational approach for evaluating the quality of movements, particularly performance precision. Therefore, the current study combined measurements of accuracy and RMSE in a cognitive-motor task to explore the elemental aspects of human motor performance.

This study investigated the interaction between distracting emotional stimuli and movement complexity on the quality of motor performance. A modified oddball paradigm was utilized to separate the emotional stimuli as distractor, but sharing the same response process (Yuan et al., 2007, 2017; Lu et al., 2017). Response time and movement time were measured to assess performance speed, while accuracy and RMSE were determined by evaluating the precision of the motor performance in a cognitive-motor task. Regarding chronometric measurements, we hypothesized that cognitive-motor performance would be differentially affected by the distracting emotional stimuli. Specifically, we predicted that the reaction time would be extended by the distracting emotional stimuli compared to the neutral situation. In comparison, movement time was expected to take longer when performing more complex movement. We also hypothesized that there would be an interaction between the distracting emotional stimulus and movement complexity on accuracy, with the highest precision in motor performance occurring in the presence of a positive stimulus under more complex movement.

This study investigated the impact of distracting emotional stimuli on the cognitive-motor performance of different types of movement. Targeted movement was impacted by distracting emotional stimuli in terms of both speed and the precision of drawing.

We showed that the distractor stimuli (i.e., emotional stimuli) induced a longer reaction time compared to standard stimuli (i.e., neutral stimuli). Adjusted movement time was longer when drawing the polygons compared to triangles. Negative stimuli were only associated with reduced accuracy compared to positive and neutral stimuli when participants performed less complicated movement (i.e., drawing the triangle). In contrast, for distracting positive stimuli, RMSE was greater for those drawing polygons compared to triangles. Our findings support those of previous studies using the key-pressing task in the presence of emotional stimuli, along with the concept that movement precision (as assessed by the RMSE) is moderated by both the movement type and distracting emotions (Lu et al., 2017).

Our results showing the effect of distracting emotional stimuli on accuracy support those of previous studies (Fanselow, 1994). Specifically, movement accuracy was lower in the presence of negative and positive distractors compared to standard ones. Furthermore, these effects had different patterns when drawing complicated versus less complicated shapes. Compared to positive stimuli, only the negative distractor impacted the accuracy of movement for complicated drawings. This might be explained by the fact that negative distractors potentially contain dangerous or threatening information, driving different allocations to attention (Soares et al., 2009). The more complicated task had higher accuracy, which might be because it required more focused attention compared to the less complicated task (Murphy et al., 2016). In contrast, previous studies obtained different outcomes when comparing the effects of negative and positive stimuli. Some studies showed that negative stimuli tend to impair accuracy more than positive stimuli (Coombes et al., 2005), while others obtained the opposite results (Most et al., 2007). Our study implied that this emotional effect could be modulated by the complexity of the motor task. A positive background did not influence the accuracy of completing the drawing task. Interestingly, accuracy was only impaired by a negative distractor when the task was relatively less complex. During motor planning, more complex movement (i.e., drawing polygons) required more attention at the start of movement.

To investigate the accuracy in a refined way, we used RMSE to assess the precision of the movement. As expected, the RMSE values showed a different trend to accuracy values. The RMSE values of different movement types varied in the presence of positive backgrounds but not with negative backgrounds. RMSE measures the quality of movement performance by describing the precision of drawing performance. Interestingly, after the positive background appeared, polygons were drawn with greater precision compared to triangles. Usually, polygons are considered to be more complex to draw than triangles. We also expected that the participants would perform better (i.e., more precision) in drawing less complicated shapes. However, this phenomenon was only detected with the negative distractor, although the results were not significant. After exposure to the positive distractor, the more complicated movement (i.e., drawing polygons) might have required more attention compared to the less complicated movement (i.e., drawing triangles), resulting in greater precision (i.e., higher RMSE) for the complicated movement. However, the effect of emotion on precision has not been previously reported. We showed that RMSE varied, allowing minor errors that are ignored by accuracy indices to be captured. Thus, RMSE is an effective measure of kinematic indices.

The reaction time and movement time after exposure to emotional stimuli were generally supported previous studies. The only difference was that the reaction time was longer after emotional distractors (both positive and negative) compared to neutral stimuli. This result might be attributed to the experimental design, rather than the properties of the pictures. Shorter reaction times in the current study were invoked by the standard stimulus, which appeared more times than the deviated stimuli (i.e., emotional stimuli). Consequently, the less frequent deviated stimuli would have longer reaction times compared to the standard stimuli, as previously detected by our group. When using a modified oddball task, the reaction time in the presence of deviant stimuli are processed via the same cognitive process; consequently, the reaction times to these deviant stimuli tend to be similar (Yuan et al., 2007; Naugle et al., 2010, 2011; Lu et al., 2017). A previous study also reported that the movement time was impaired when participants were briefly exposed to negative stimuli compared to positive stimuli (Coombes et al., 2005). However, neither reaction time nor movement time was significantly different after the appearance of positive stimuli compared to negative stimuli in the current study. This discrepancy might be caused by arousal. In general, arousal tends to be greater in response to negative stimuli compared to positive stimuli (Lang et al., 1993; Feng et al., 2014; Lu et al., 2017). Besides, our control analysis showed, comparing to the first presentation, the reaction time and movement time was shorter with the second presentation. The emotional adaption might reduce the influence on the movement performance. However, further study should be taken to investigate this speculation.

The current study aimed to characterize the influence of emotional stimuli on different types of motor performance. The modified oddball paradigm was used to provide the same cognitive processing, and to compare the effects of distracting emotional stimuli. We demonstrated that both valence and movement types interacted to affect accuracy and RMSE. Accuracy increased when participants were exposed to negative distractors during less complicated movement. In comparison, the performance precision of complicated movement was greater in more complicated movement compared to less complicated movement, especially in the presence of positive distractors.

Although the paradigm that we utilized in the current study was verified in many previous studies, this paradigm was limited by neutral stimuli having a weakened function. The ratio of stimuli could be modified in future studies. Also, working memory processes were involved in the current experimental design, but the influence was not measured. Further study should consider the interplay between emotions and working memory (Buttafuoco et al., 2018). Last but not least, an electroencephalogram or near-infrared spectrum could be used in future studies to evaluate the brain activities on the examined phenomena (Chen et al., 2020).

Overall, both the type of emotion and type of movement were associated with the quality of movement performance. Movement time was primarily affected by movement complexity. In the presence of negative emotional distractors, movement complexity impacted accuracy. In contrast, in the presence of positive emotional distractors, movement type affected precision. In conclusion, movement precision is an important feature of emotional embodiment that should be incorporated in future studies.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by the ethics committee of the Shanghai University of Sport. The patients/participants provided their written informed consent to participate in this study.

YL: designed the experiment and wrote the manuscript. TW: collected the data, analyzed the data, and wrote the manuscript. QL: collected the data. ZC: wrote the experiment codes. All authors contributed to the article and approved the submitted version.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.