Four-month-old infants sometimes can perceive the unity of a partly hidden object. In each of a series of experiments, infants were habituated to one object whose top and bottom were visible but whose center was occluded by a nearer object. They were then tested with a fully visible continuous object and with two fully visible object pieces with a gap where the occluder had been. Pattems of dishabituation suggested that infants perceive the boundaries of a partly hidden object by analyzing (...) the movements of its surfaces: infants perceived a connected object when its ends moved in a common translation behind the occluder. Infants do not appear to perceive a connected object by analyzing the colors and forms of surfaces: they did not perceive a connected object when its visible parts were stationary, its color was homogeneous, its edges were aligned, and its shape was simple and regular. These findings do not support the thesis, from gestalt psychology, that object perception first arises as a consequence of a tendency to perceive the simplest, most regular configuration, or the Piagetian thesis that object perception depends on the prior coordination of action. Perception of objects may depend on an inherent conception of what an object is. (shrink)

Exploiting the skills of others enables individuals to reduce the risks and costs of resource innovation. Social corvids are known to possess sophisticated social and physical cognitive abilities. However, their capacity for imitative learning and its inter-individual transmission pattern remains mostly unexamined. Here we demonstrate the large-billed crows' ability to learn problem-solving techniques by observation and the dominance-dependent pattern in which this technique is transmitted. Crows were allowed to observe one of two box-opening behaviours performed by a dominant or subordinate (...) demonstrator and then tested regarding action and technique. The observers successfully opened the box on their first attempts by using non-matching actions but matching techniques to those observed, suggesting emulation. In the subsequent test sessions, dominant observers consistently used the learned technique, whereas subordinates learned alternative techniques by explorative trial and error. Our findings demonstrate crows' capacity to learn by observing behaviours and the effect of dominance on transmission patterns of behavioural skills. Keywords: social learning; imitation; emulation; affordance; culture; innovation. (shrink)

To what extent do keas, Nestor notabilis, learn from each other? We tested eighteen captive keas, New Zealand parrots, in a tool use task involving visual feature discrimination and social learning. The keas were presented with two adjacent tubes, each containing a physically distinct baited platform. One platform could be collapsed by insertion of a block into the tube to release the bait; the other platform could not be collapsed. In contrast to birds that acted on their own, birds that (...) could observe a demonstrator bird operated the collapsible platform first. However, they soon changed their behaviour to inserting blocks indiscriminately in either tube. When we reversed the collapsibility of the platforms, only adult observers but neither their demonstrators that had individually learnt nor the juveniles immediately altered their former preference. Observers, however, did not simply reverse their initial preference but rather moved to and then stayed at a chance performance as to where to insert a block first. In conclusion, the keas' overt exploration soon overrode the effect of social learning. We argue that such behaviour might help keas to find more efficient extractive foraging techniques in their native variable, low-risk environment. Keywords: tool use behaviour; social learning; reversal learning; physical cognition. (shrink)

To what extent do keas, Nestor notabilis , learn from each other? We tested eighteen captive keas, New Zealand parrots, in a tool use task involving visual feature discrimination and social learning. The keas were presented with two adjacent tubes, each containing a physically distinct baited platform. One platform could be collapsed by insertion of a block into the tube to release the bait; the other platform could not be collapsed. In contrast to birds that acted on their own (“individual (...) learners“), birds that could observe a demonstrator bird operated the collapsible platform first. However, they soon changed their behaviour to inserting blocks indiscriminately in either tube. When we reversed the collapsibility of the platforms, only adult observers but neither their demonstrators that had individually learnt nor the juveniles immediately altered their former preference. Observers, however, did not simply reverse their initial preference but rather moved to and then stayed at a chance performance as to where to insert a block first. In conclusion, the keas' overt exploration soon overrode the effect of social learning. We argue that such behaviour might help keas to find more efficient extractive foraging techniques in their native variable, low-risk environment. Keywords: tool use behaviour; social learning; reversal learning; physical cognition. (shrink)

Grey parrots do not acquire referential English labels when tutored with videotapes displayed on CRT screens if socially isolated, reward for attempted labels is possible, trainers direct birds’ attention to the monitor, live video feed avoids habituation or one trainer repeats labels produced on video and rewards label attempts. Because birds learned referential labels from live tutor pairs in concurrent sessions, we concluded that video failed because input lacked live social interaction and modeling. Recent studies, however, suggest that standard CRT (...) monitor flickering could instead have prevented learning. Using an LCD monitor, we found that eliminating flickering did not enable birds to learn from video under conditions of limited social interaction. Results emphasize the role of social interaction in referential label learning and may generalize to other systems. (shrink)

Exploiting the skills of others enables individuals to reduce the risks and costs of resource innovation. Social corvids are known to possess sophisticated social and physical cognitive abilities. However, their capacity for imitative learning and its inter-individual transmission pattern remains mostly unexamined. Here we demonstrate the large-billed crows' ability to learn problem-solving techniques by observation and the dominance-dependent pattern in which this technique is transmitted. Crows were allowed to observe one of two box-opening behaviours performed by a dominant or subordinate (...) demonstrator and then tested regarding action and technique. The observers successfully opened the box on their first attempts by using non-matching actions but matching techniques to those observed, suggesting emulation. In the subsequent test sessions, dominant observers (i.e. those dominant to the bird acting as demonstrator) consistently used the learned technique, whereas subordinates (i.e. those subordinate to the bird acting as demonstrator) learned alternative techniques by explorative trial and error. Our findings demonstrate crows' capacity to learn by observing behaviours and the effect of dominance on transmission patterns of behavioural skills. Keywords: social learning; imitation; emulation; affordance; culture; innovation. (shrink)