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Apart from language, our gaze is arguably the most important means of communication. Where we look lets others know what we are interested in and allows them to join our focus of attention. In several studies our group investigated the neuronal basis of gaze following behavior in humans and macaques and described theGaze following patchin the posterior temporal cortex as being of central importance for this function. To our knowledge, this makes it the most promising candidate for Simon Baron-Cohen’sEye-Direction-Detector, an integral part of his influentialMindreading System.With the latter, Baron-Cohen proposed a network ofdomain-specificneurocognitive modules that are necessary to establish aTheory of Mind- the attribution of mental states to others. The tenet of domain-specificity requires that the EDD processes only and exclusively eye-like stimuli with their typical contrast and movement properties. In the present fMRI study, we aim to critically test if the GFP fulfills this criterion. Specifically, we will test if it is equivalent to or different from the visual motion processing areas located in the same part of the brain. Since our experiments capture the full-behavioral relevance of gaze-following behavior and are specifically designed to reveal an EED our results will provide strong support or rejection of a central property Baron-Cohen’s Mindreading-System –domain specificity.

We use others’ gaze to identify their object of attention. Guterstam and colleagues suggested that the capability to link the gaze of observed persons to their object of interest is mediated by an imaginary “gaze beam” that emanates from the others’ eyes and moves through space. The central tenet of this hypothesis is that the gaze beam recruits the visual motion processing system. Görner et al. argued that the experimental evidence supports not only this “gaze beam hypothesis” but also a different interpretation, namely the beholder´s understanding that the other displays a particular object-related intention. We refer to this as “intentional binding hypothesis”. This assignment of an intention may involve the prediction of an upcoming movement of the observed person engaging the same system. To critically compare the explanatory power of the two hypotheses, we aim to replicate and extend the original psychophysical study by Guterstam et al. to test the alternative hypothesis.