Velocity-based motion categorization by pigeons.

Abstract

To examine if animals could learn action-like categorizations in a manner similar to noun-based categories, eight pigeons were trained to categorize rates of object motion. Testing 40 different objects in a go/no-go discrimination, pigeons were first trained to discriminate between fast and slow rates of object rotation around their central y-axis. They easily learned this velocity discrimination and transferred it to novel objects and rates. This discrimination also transferred to novel types of motions including the other two axes of rotation and two new translations around the display. Comparable tests with rapid and slow changes in the objects' size, color, and shape failed to support comparable transfer. This difference in discrimination transfer between motion-based and property-based changes suggests the pigeons had learned motion concept rather than one based on change per se. The results provide evidence that pigeons can acquire an understanding of motion-based actions, at least with regard to the property of object velocity. This may be similar to our use of verbs and adverbs to categorize different classes of behavior or motion (e.g., walking, jogging, or running slow vs. fast).

Simultaneous Discrimination of Speed is More Difficult than Simultaneous Discrimination of Size for Both Pigeons and People

“…Unlike Cook et al (2011) who reported a reliable discrimination after as little as six training sessions (or 480 trials), we have observed no noticeable learning across two weeks of training (a total of 1,680 trials). Importantly, the rotational difference between our stimuli, and therefore their discriminability, was comparable to that in Cook et al's (2011) study.…”

“…In Experiment 3, we found that pigeons appeared to be more sensitive to the differences in size than to the differences in speed in a two-alternative forced-choice task; the same was true for human participants (cf Figure 4). Overall, our results are not consistent with many earlier reports of motion discrimination in pigeons that suggested high sensitivity to object speed (Cook et al, 2011;Herbranson et al, 2002;Koban & Cook, 2009; but see Hodos, Smith, & Bonbright, 1976;Mulvanny, 1978). Importantly, the magnitude of the differences among the stimuli in our study was comparable to the previously used magnitudes.…”

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Abstract -Previous reports suggest that pigeons are highly sensitive to speed of motion (Cook, Beale, Koban, 2011;Herbranson, Fremouw, & Shimp, 2002). In contrast, we found that pigeons required more extensive training to learn speed discrimination than size discrimination (Lazareva, Young, & Wasserman, 2014).

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“…In a representative experiment, pigeons were trained to discriminate an object rotating in depth slowly (55° per second) or quickly (200° per second) in a go/no-go task (Cook, Beale, & Koban, 2011). Pigeons' discriminative performance appeared to be impressively robust: The objects rotating at 20°, 30°, 66.7°, and 85.7° per second were still classified as "slow", with a generalization decrement observed for 85.7° per second.…”

“…Because this result appeared to be at odds with the existing literature, we conducted a series of experiments systematically exploring pigeons' ability to discriminate differences in size and speed. In Experiment 1, we attempted to train pigeons to perform a two-alternative simultaneous discrimination of rotational speed, using stimuli similar to those of Cook et al (2011). In Experiment 2, we compared relative difficulty of translational speed discrimination and size discrimination in a withinsubject design.…”