Abstract
Gaze cueing paradigm (Friesen, Kingstone, 1998) is widely used to study joint attention, which is crucial for human communication and cooperation. In this paradigm, a central image of human eyes cues the future position of a periferal target. The gaze cue seems to cause reflexive spatial shifts of attention, with benefits (faster response) when the cue is valid, but no cost when it is invalid. On the one hand, this effect probably relies upon the evolutionary beneficial contrast between sclera and iris of the human eye, as the cooperative eye hypothesis states (Tomasello et al., 2007). On the other hand, it depends on the interpretation of the cue as a human gaze (Ristic, Kingstone, 2005; Takahashi, Watanabe, 2013). In our study, we assessed the contribution of these two factors to the gaze cueing effect. Two groups of participants, 20 observers each, performed the peripheral target detection task. The target could be presented after a valid, invalid or neutral gaze cue – schematic human eyes, integrated into the images of faces for one group and into the images of different inanimate objects (column speakers, ice-cream, etc.) for the other group. For the latter group, we also included fillers – images of inanimate objects without integrated eyes. In both “face” and “object” conditions, we observed a significant gaze cueing effect, but the effects produced by human faces and inanimate objects differed. A cue embedded in a face provided for faster response times, when it was valid, with no slowdown, when it was invalid. A cue embedded in an object provided for both significant benefits and significant costs. However, the effect of context turned out to be statistically insignificant, with no interaction between the factors of cue validity and context. While emphasizing the importance of the iris-sclera contrast, this result invites further investigation.