Temporal context in face perception: The interaction of competition and prediction

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A given picture of a person might look different at different times. Previous encounters with other people or in other words, the temporal context of a given face modifies its perception. Our previous research on priming and adaptation is shaping theories about the neural mechanisms and representations involved in face perception. As we are beginning to understand the relationship between these two phenomena, an account of the interaction between top-down processes, such as predictions, attentional cueing and sensory competition among stimuli becomes increasingly important. In this project proposal, we will continue to study the effect of previous experiences on face perception using psychophysical, electrophysiological and neuroimaging methods within the theoretical frame of predictive coding models. In two lines of our planned experiments we will use repeated stimuli, leading to specific, high-level aftereffects, priming or predictive cueing. In the first line we will capitalize upon the previously found interactions among multiple simultaneously presented faces (Nagy et al., 2011). First, using event-related potential (ERP) recordings we will test the temporal dynamics of sensory competition among faces. Second, we will compare the competition effect (manifested in the reduction of blood oxygen level dependent (BOLD) signal) for different stimulus categories compared to faces and will test if a prior stimulus, serving as an attentional cue is able to bias these competitions similarly for various categories or not. As a third part of this experimental line we will study how the competitive interactions of faces are modified by the so-called “body-Gestalt” effect (Miellet et al, 2011). We will test competition effects among faces and body-parts and use functional magnetic resonance imaging (fMRI) to evaluate how their neural coding changes during the perception of an entire person as a “Gestalt”.In the second line of (mostly fMRI) experiments we will concentrate on the interaction of predictive cueing, attention and adaptation. In our first experiments, we will try to disentangle the effect of expectation from that of passive stimulus probability by manipulating both effects orthogonally. Second, using ambiguous stimuli (Cziraki et al., 2010) we will test whether prediction affects the neuronal responses per se or rather only their suppression, due to adaptation. Finally, we will test how predictive cueing affects sensory competition among faces and other stimulus categories.