Authors:

CALDER, A.J., LAWRENCE, A.D., KEANE, J., Scott, S.K., Owen, A., Christoffels, I and Young, A.W

Reference:

Year of publication:

2002

CBU number:

5525

Abstract:

Baron-Cohen (1997, MIT Press) has suggested that the interpretation of gaze plays an important role in a normal functioning theory of mind system. Consistent with this suggestion, functional imaging research has shown that both theory of mind (ToM) tasks and eyegaze processing engage a similar region of posterior superior sulcus (STS). However, a second brain region associated with ToM, the medial prefrontal cortex, has not been identified by previous eyegaze studies. We discus the methodological issues that may account for the presence of medial prefrontal activation in these experiments and present a PET study that controls for these factors. Our experiment included three conditions in which the proportions of faces gazing at, and away from, the participant, were as follows: 100% direct (0% averted), 50% direct-50 averted, and 100% horizontally averted (0% direct). Two control conditions were also included in which the faces' gaze were averted down, or their eyes were closed. Contrasts comparing the gaze conditions with each of the control conditions revealed medial frontal involvement. Parametric analyses showed a significant linear relationship between increasing proportions of horizontally averted gaze and increased rCBF in the medial prefrontal cortex. The opposite parametric analysis (increasing proportions of direct gaze) was associated with increased rCBF in a number of areas including the superior and medial temporal gyri. Our results are consistent with the proposal that the presentation of highly social stimulus, such as gaze, is in itself sufficient to engage the mechanisms in attributing mental states to others.