Arousal & Balance
Emotion influences parameters of goal-directed whole-body movements in several ways. I analyze various spatial and temporal parameters of the center of pressure during quiet standing and during gait initiaton, to study how they are coupled to emotional states.
Gait Initiation Parameters
- Reaction time. Time interval between picture onset or offset (cue for GI) and the moment at which the force exceeds some threshold.
- APA amplitude. The anticipatory postural adjustment (APA) representing the build-up of momentum to accelerate the body in the required direction.
- Peak velocity. Maximum velocity of the COP during a step.
- Step length. The difference along the AP-axis between the initial position of the COP and its final position.
- Postural immobility. Directly at picture onset there may a fast (reflex-like) response to strong emotions, such as a ‘freezing’ response.
Most of the parameters are sensitive to the emotional content of stimuli
- Individuals are faster to initiate a forward step towards a pleasant picture than towards an unpleasant picture; the effect is mainly apparent in the early components of the COP.
- This effect only appears when the emotion has to be processed and attended to, and disappears when it is task-irrelevant.
- Backward stepping (‘avoidance’) is not affected by emotion; individuals are equally fast to initiate a backward step away from a pleasant picture as from an unpleasant picture (This finding has recently been accepted for publication).
- The effects of emotion on forward GI are dependent on viewing duration of the stimulus. In some conditions the facilitating effect could even be reversed.
In future experiments we will extend this paradigm to selected groups, such as anxiety and autism, to test whether whole-body approach-avoidance tendencies are disregulated in these groups. An unresolved question is to what extent these findings are a result of the valence (pleasantness-unpleasantness) of the stimuli, or due to the arousal that such images generate in viewers. In practice it is difficult to disentangle these factors because they are strongly correlated.
Related Research Themes & Projects
One of the tenets of the embodied cognition theory is that mental states are grounded in the physical body, which can manifest itself as reciprocity between mental states and bodily states.