Recognition of static and dynamic images of depth-rotated human faces by pigeons

Abstract

In three experiments, we examined pigeons' recognition of video images of human faces. In Experiment 1, pigeons were trained to discriminate between frontal views of human faces in a go/no-go discrimination procedure. They then showed substantial generalization to novel views, even though human faces change radically as viewpoint changes. In Experiment 2, the pigeons tested in Experiment 1 failed to transfer to the faces dynamically rotating in depth. In Experiment 3, the pigeons trained to discriminate the dynamic stimuli showed excellent transfer to the corresponding static views, but responses to the positive faces decreased at novel viewpoints outside the range spanned by the dynamic stimuli. These results suggest that pigeons are insensitive to the three-dimensional properties of video images. Consideration is given to the nature of the task, relating to the identification of three-dimensional objects and to perceptual classifications based on similarity judgments.

Learning-related shifts in generalization gradients for complex sounds

“…This finding is consistent with recent reports of peak shift effects in humans trained to distinguish faces varying along a continuum (Lewis & Johnston, 1999; Spetch et al, 2004; McLaren & Mackintosh, 2002), and pigeons trained to discriminate multi-item visual displays (Honig & Stewart, 1993; Wills & Mackintosh, 1998). The current data afford more direct comparisons across species than studies of humans generalizing across faces, however, because faces are especially salient stimuli for humans (Jitsumori & Makino, 2004), and participants have an enormous amount of prior experience distinguishing faces prior to training. In contrast, participants were unlikely to have experienced FM sweep trains before participating in this experiment, and the sounds had no natural significance.…”

Do Animals Recognize Pictures as Representations of 3D Objects?

“…It is even more difficult to imagine that pigeons perceive a solid object when it is rotating in depth but keeping its location in the video (but see Cook & Katz, 1999;Koban & Cook, 2009). Jitsumori and Makino (2004) found with pigeons that dynamic 3D rotations of human faces in depth contributed little beyond what would be expected from the additional views provided by the motion. The negative finding suggests that the pigeons treated the static and the dynamic views of the same face differently but does not necessarily exclude the possibility that they perceived a 3D object in the dynamic video.…”

Family resemblances facilitate formation and expansion of functional equivalence classes in pigeons

“…A possible limitation of this study is the difficulty in identifying the physical features actually used by pigeons to discriminate human face stimuli that vary along many dimensions (Huber, Troje, Loidolt, Aust, & Grass, 2000;Jitsumori & Makino, 2004;Troje, Huber, Loidolt, Aust, & Fieder, 1999). It is therefore impossible to specify how the pigeons internally represented the equivalence classes consisting of human face stimuli.…”