Abstract
Purpose :
Perceptual adaptation and visual short term memory can be studied using manipulations of temporal context. Here we used the phenomenon of hysteresis, which manifests as positive, if there is a tendency to maintain the percept in short term memory, or negative, if adaptation prevails and there is a shift to the opposite percept during the temporal trajectory.
Here, we studied the existence of perceptual hysteresis in the process of high-level emotion recognition in biological motion patterns and the neural correlates underlying these mechanisms, by combining psychophysics and neuroimaging.
Methods :
This study was conducted in two sessions. In the first, participants (n=22) were asked to observe smooth continuous transitions between biological motion patterns displaying two emotions, happiness and sadness, and to report the initially perceived emotion as well as the moments of perceptual switch, both to the neutral state and to the opposite emotion. The second consisted of a fMRI acquisition while participants (n=20) performed the same task. All participants provided written informed consent as approved by the Ethics Committee of the Faculty of Medicine of the University of Coimbra, in accordance with the Declaration of Helsinki.
Results :
Behavioural assessment confirmed the existence of perceptual hysteresis, revealing a predominance of positive hysteresis overall (68.64%) but with a great contribution of negative hysteresis (31.36%) especially in the direction from sadness to happiness, suggesting the presence of a happiness bias (X2(1,N=507)=14.713, p<0.001). The results from the fMRI data show a stronger activation in the right hemisphere (p<0.05(FDR)), suggesting that there is a right lateralization effect in the task of emotion recognition in biological motion patterns.
Conclusions :
The interplay between positive and negative hysteresis suggests a competition between both visual persistence and adaptation mechanisms. Furthermore, the strong presence of negative hysteresis in the direction from sadness to happiness demonstrates a positive bias in emotion recognition in biological motion. The lateralization effect provoked by this task makes it an interesting tool to further explore the impairments regarding the lateralization in the visual perception present in several neurodevelopmental diseases, such as autism.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.