Gravity and solidity in four great ape species (Gorilla gorilla, Pongo pygmaeus, Pan troglodytes, Pan paniscus): Vertical and horizontal variations of the table task.

Abstract

Three experiments modeled after infant studies were run on four great ape species (Gorilla gorilla, Pongo pygmaeus, Pan troglodytes, Pan paniscus) to investigate their reasoning about solidity and gravity constraints. The aims were: (a) to find out if great apes are subject to gravity biased search or display sensitivity for object solidity, (b) to check for species differences, and (c) to assess if a gravity hypothesis or more parsimonious explanations best account for failures observed. Results indicate that great apes, unlike monkeys, show no reliable gravity bias, that ape species slightly differ in terms of their performance, and that the errors made are best explained by a gravity account.Keywords: invisible displacement, object solidity, gravity error, naïve physicsVarious constraints, such as gravity, inertia, or solidity, act upon a moving object, shaping its pathway through time and space. To locate an invisibly displaced object, an infant must have some knowledge of how these constraints interact to determine the future trajectory of the object moving out of sight (Baillargeon,

Domesticated dogs’ (Canis familiaris) use of the solidity principle

“…These subjects all failed to reason about the location of a hidden barrier when reaching for an invisibly displaced object, but evidenced sensitivity to solidity information in expectancy violation paradigms (Spelke et al 1992;Berthier et al 2000;Hood et al 1999;Santos 2004;Santos et al 2006). Our results, however, do accord with the Wndings of Cacchione et al (2009) indicating that apes act in accordance with solidity and proximity information in conjunction in tasks requiring judgments regarding object movement in horizontal trajectories. Additionally, these results suggest that dogs in this paradigm understood invisible displacement.…”

“…Researchers have observed comparable dissociations between expectancy violation and search paradigms with some adult non-human primates in tasks where subjects are required to reach for objects that undergo interactions with other objects (e.g., Hauser 2001;Hauser et al 2001;Santos and Hauser 2002;Santos 2004;Santos et al 2006). In contrast to these results, Cacchione et al (2009) recently observed that apes successfully utilized solidity and proximity information in conjunction to make correct choices about object movement along horizontal trajectories. However, it is unclear whether apes would have been successful using solidity information alone.…”

If at first you don't succeed… Studies of ontogeny shed light on the cognitive demands of habitual tool use

“…However, when the object was dropped behind a screen onto an occluded shelf, both groups show a bias for searching beneath the shelf, perhaps owing to experience inducing an overgeneralized expectation for objects to be located at ground level. Older children (2.5-3 years) and mature apes show evidence of being able to overcome this bias and search in the correct location [74,76]. In other problem-solving contexts, both monkeys and infants show perseverative reaching (i.e.…”

Developing understanding of object fall: Going beyond inhibitory processes

“…Taken as a whole, the picture could be interpreted as failure to inhibit an early established principle (straight‐down fall), with the implication that progress depends upon greater inhibitory control. Interpretations of this kind have already appeared in the literature (e.g., Cacchione, Call, & Zingg, ; Hood et al ., ), no doubt with recognition that they bring object fall into line with much contemporary theorizing in developmental psychology.…”