Applying Bubbles to Localize Features That Control Pigeons' Visual Discrimination Behavior.

Abstract

The authors trained pigeons to discriminate images of human faces that displayed: (a) a happy or a neutral expression or (b) a man or a woman. After training the pigeons, the authors used a new procedure called Bubbles to pinpoint the features of the faces that were used to make these discriminations. Bubbles revealed that the features used to discriminate happy from neutral faces were different from those used to discriminate male from female faces. Furthermore, the features that pigeons used to make each of these discriminations overlapped those used by human observers in a companion study (F. Gosselin & P.G. Schyns, 2001). These results show that the Bubbles technique can be effectively applied to nonhuman animals to isolate the functional features of complex visual stimuli.

Pigeons use high spatial frequencies when memorizing pictures.

“…For example, when both animals and humans are taught to complete different kinds of tasks with equivalent stimuli, they often process those stimuli in different ways and attend to different details of those same stimuli (e.g., Gibson et al, 2005). This attentional effect is almost certainly true in the spatial frequency domain, where different kinds of spatial frequencies might be critically important for performing different kinds of scene categorizations (Oliva and Torralba, 2001), a task that pigeons have recently been shown to accomplish (Kirkpatrick, Bilton, Hansen, and Loschky, 2014).…”

Which traits do observers use to distinguish Batesian mimics from their models?

“…The present work used a short presentation of a low resolution image in order to best resemble the situation in which a predator must make a quick decision based on an insect viewed from a distance, with any hesitation allowing the prey a chance to escape (Chittka and Osorio 2007;Abbott and Sherratt 2013). Furthermore, presenting volunteers with a choice that is based on a limited subset of information allows conclusions to be drawn about which traits are the most relevant to the signal receiver (Gibson et al 2005). Nonetheless, future studies could follow a similar format to the present work, replacing humans with more relevant predators, and perhaps using 3D models rather than photographs, in order to further increase the realism of the scenario.…”

Discrimination of human faces by archerfish (Toxotes chatareus)

“…There is some evidence that animals lacking a neocortex, namely bees16 and birds17181920212223, are capable of some degree of human facial discrimination. Although the experiments with bees are limited by the small number of test stimuli (a total of four human faces were presented to the bees)16, it does indicate that the bee visual recognition system is adequate for a limited version of the task.…”