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EYE MOVEMENTS AND PUPIL REACTIONS DURING AFFECTIVE PICTURE VIEWING
MICCOLI, LAURA
2006-04-28
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Contributor(s)
AGOSTINI, TIZIANO
Abstract
It has been suggested that emotions result from the activation of a defensive and an appetitive motivational system, that evolved to promote the survival of the individual and its specie. Linguistic, behavioral, and psychophysiological reactions to a wide range of visual affective stimuli supported this bi-dimensional approach to emotion and motivation. Within this theoretical framework we investigated eye movements and pupil diameter reactions to affective images. In the first study we presented color pictures balanced across affective valence, arousal, and perceptual composition dimensions. A higher number of ocular movements followed the presentation of emotional and perceptually more complicated images. Moreover, pupil diameter dilated the most during affectively unpleasant stimuli, but it was not influenced by pictures' perceptual composition when emotional images were displayed. To replicate and deepen these results we conducted a second study, displaying stimuli in grayscale and controlling their luminosity in order to rule out possible perceptual confounds. Eye movements showed the same pattern of results. After controlling these physical features, we found that pupil diameter was larger during both appetitive and distasteful compared to neutral stimuli. Additional tests indicated that the most arousing stimuli elicited the greatest pupillary response, regardless their hedonic valence. In this second study we also delivered acoustic startle probes during picture viewing to test whether pupil diameter response to the probes was modulated by the affective state evoked by the foreground image. Startle reflex was further investigated recording skin conductance and electromyographic blink reactions to the probes. In line with previous results, EMG blink was modulated by ongoing valence: Pleasant images evoked significantly smaller blinks than unpleasant images. On the contrary, neither skin conductance nor pupil diameter responses to startle probes were influenced by the ongoing affective state. These results are discussed referring to data emerged thus far within the bi-dimensional approach to emotional reactions. In summary, both eye movements and pupil diameter reacted to the emotionality of pictures. This effect emerged also when we controlled for potential perceptual confounds. In general, we found the largest pupillary and ocular reactions to the most arousing stimuli. Within the motivational model of emotion, these data are interpreted as indicating that picture contents associated to stronger motivational states cause a wider activation of the appetitive an d the defensive motivational system.
Insegnamento
Publisher
Università degli studi di Trieste
Languages
en
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