Thesis defense Maria Lojowska (Donders series 352)

28 February 2019

Promotor: prof. dr. K. Roelofs, co-promotor: dr. E. Hermans

Freeze to see: The effect of threat on detention of coarse visual features

During anticipation of potential threats, humans show freezing behavior. Freezing is characterized by decreased body motion, increased muscle tension and autonomic responses that prepare our body for an optimal reaction to danger: fight, flight or remaining frozen. But how do we make this choice?  In this thesis, I asked whether our visual perception is altered during freezing, which may be relevant for threat detection and these action choices. We found that rather than an overall visual enhancement, we tend to perceive coarse visual characteristics better than visual details during freezing.  This suggests that perception of potentially dangerous cues, even if we are unable to recognize it due to a lack of visual details, can be particularly adaptive for fast defensive choices under threat. Better safe than sorry, simply said. This shift in visual perception is furthermore influenced by pupil dilation, and occurs also outside of visual awareness. Overall, this thesis shows that bodily preparation for action during freezing occurs simultaneously with visual adaptations, which together may optimize our chances for survival in threatening situations. ​