Categorization of natural movements by pigeons: visual concept discrimination and biological motion.
Pigeons can group living actions into a concept and still recognize that concept when only the motion pattern remains.
01Research in Context
What this study did
Researchers showed pigeons short video clips. Some clips showed another pigeon pecking at grain. Other clips showed hopping, drinking, or preening.
The birds had to learn which clips earned food. A pecking video meant food was coming. Non-pecking videos meant no food. Later, the team tested if the birds still chose when the videos turned into moving dots of light.
What they found
The pigeons quickly learned to peck only for the pecking videos. They ignored the other actions. When the same motions were shown only as moving dots, most birds still picked the pecking motion.
This means the birds had formed a concept of "pecking" that went beyond the exact pictures they saw.
How this fits with other research
Hodos et al. (1976) first proved pigeons could see simple motion as slow as 5 mm per second. The new study adds that pigeons can also sort complex, natural movements into categories.
Adams (1980) used the same autoshaping setup to teach pigeons to count their own pecks. The 1998 paper swaps response-count for biological motion, showing the method works for very different cues.
Koenen et al. (2016) later recorded pigeon brain cells while the birds viewed picture categories. Their neural clusters match the behavioral choice seen here, linking brain data to the earlier performance.
Why it matters
If pigeons can sort actions into concepts, so can many learners. When you teach a child to label "waving" versus "pointing," start with clear videos instead of still photos. After the child masters the video, test with simple stick-figure dots. The motion cue alone may keep the concept alive, just like it did for the pigeons.
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Film a short video of the target action, show it for two trials, then switch to a point-light version and see if the learner still names or imitates the action.
02At a glance
03Original abstract
In three experiments, pigeons were exposed to a discriminated autoshaping procedure in which categories of moving stimuli, presented on videotape, were differentially associated with reinforcement. All stimuli depicted pigeons making defined responses. In Experiment 1, one category consisted of several different scenes of pecking and the other consisted of scenes of walking, flying, head movements, or standing still. Four of the 4 birds for which pecking scenes were positive stimuli discriminated successfully, whereas only 1 of the 4 for which pecking was the negative category did so. In the pecking‐positive group, there were differences between the pecking rates in the presence of the four negative actions, and these differences were consistent across subjects. In Experiment 2, only the categories of walking and pecking were used; some but not all birds learned this discrimination, whichever category was positive, and these birds showed some transfer to new stimuli in which the same movements were represented only by a small number of point lights (Johansson's “biological motion” displays). In Experiment 3, discriminations between pecking and walking movement categories using point‐light displays were trained. Four of the 8 birds discriminated successfully, but transfer to fully detailed displays could not be demonstrated. Pseudoconcept control groups, in which scenes from the same categories of motion were used in both the positive and negative stimulus sets, were used in Experiments 1 and 3. None of the 8 pigeons trained under these conditions showed discriminative responding. The results suggest that pigeons can respond differentially to moving stimuli on the basis of movement cues alone.
Journal of the experimental analysis of behavior, 1998 · doi:10.1901/jeab.1998.70-281