Faces capture the visuospatial attention of chimpanzees (Pan troglodytes): evidence from a cueing experiment

Masaki Tomonaga and Tomoko Imura

顔は社会的に重要な刺激であり、ヒトでは視空間的注意を容易に捕捉することが知られている。チンパンジーにとっても顔は社会生活を送る上で重要な刺激であるが、顔に関連する注意のメカニズムについては不明な点が多い。そこで、本研究では若いチンパンジー3個体に単純な反応時間課題の実験に参加してもらい、顔や非顔刺激を含む先行手がかりがいかにチンパンジーの視空間注意を補足するかを検討した。その結果、標的刺激が出現する位置にチンパンジーの顔が先行して提示された場合、逆の場合に比べて反応時間が有意に速くなるという手がかり効果が認められた。このような効果はバナナの写真を先行手がかりとした場合には認められなかった。さらに、この効果はヒトの顔に対しても生じたのに対し、倒立提示されたチンパンジーの顔では認められなかった。このことは、今回の先行手がかりによる注意の捕捉効果は、チンパンジーが顔刺激を「顔」として処理した結果生じている可能性を示唆している。

Frontiers in Zoology 2009, 6:14 doi:10.1186/1742-9994-6-14 Published: 23 July 2009

Faces, as socially relevant stimuli, readily capture human visuospatial attention. Although faces also play important roles in the social lives of chimpanzees, the closest living species to humans, the way in which faces are attentionally processed remains unclear from a comparative-cognitive perspective. In the present study, three young chimpanzees (Pan troglodytes) were tested with a simple manual response task in which various kinds of photographs, including faces as non-informative cues, were followed by a target. When the target appeared at the location that had been occupied by the face immediately before target onset, response times were significantly faster than when the target appeared at the opposite location that had been by the other object. Such an advantage was not observed when a photograph of a banana was paired with the other object. Furthermore, this attentional capture was also observed when upright human faces were presented, indicating that this effect is not limited to own-species faces. On the contrary, when the participants were tested with inverted chimpanzee faces, this effect was rather weakened, suggesting the specificity to upright faces. Conclusion Chimpanzee's visuospatial attention was easily captured by the face stimuli. This effect was face specific and stronger for upright faces than inverted. These results are consistent with those from typically developing humans.

News URL

http://www.sciencedaily.com/releases/2009/07/090722191208.htm

http://www.eurekalert.org/pub_releases/2009-07/bc-clh072109.php

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