Abstract
Memory-based attractiveness integration is implicit and nonlinear, as we demonstrated with images featuring a central face (FC) and a surrounding natural scene (NS) (Shimojo et al., VSS'09). Here, we aimed to see how the task-irrelevant surround affects attractiveness of the central stimulus and vice versa, using hair (HR) and face (FC). There is evidence that HR is indeed a surrounding, accessory part of the holistic FC perception (Ellis et al., 1980), and both are processed in the face-specific temporal area (Kanwisher et al., 1997).
Eight FC images (4 attractive and 4 less attractive FCs), and 16 HR pictures (4 colors, 2 lengths and 2 shapes) were selected from a pre-rated set. Each FC and HR were combined in the natural spatial alignment, and subjects were asked to rate attractiveness of 1) FC only or 2) HR only in a 7-point scale in separate sessions.
Results of 1) show that, when FC is shown with an attractive HR, the attractiveness of FC was higher than with a less attractive HR, even though subject was asked to focus only on the FC. Results of 2) were symmetrical to those of 1) in that the task-irrelevant FC affects attractiveness of HR. The overall patterns of the results cannot be simply interpreted as the subjects neglecting the “ONLY” instruction, because the “FC only” attractiveness with HR is exceedingly lower than the range predicted from weighted averaging of the pre-rated attractiveness of HR and FC.
These results seem difficult to interpret unless we accept two possibilities: (a) the attractiveness of the task-irrelevant surround is implicitly “imported” into that of the central stimulus, and (b) something more nonlinear than just averaging occurs particularly in the FC only evaluation with HR.
Kao Corporation, JST.ERATO Shimojo Implicit Brain Project, Tamagawa-Caltech gCOE.