The interface between morphology and action planning: a comparison of two species of New World monkeys

Recent research with several species of nonhuman primates suggests sophisticated motor-planning abilities observed in human adults may be ubiquitous among primates. However, there is considerable variability in the extent to which these abilities are expressed across primate species. In the present experiment, we explore whether the variability in the expression of anticipatory motor-planning abilities may be attributed to cognitive differences (such as tool use abilities) or whether they may be due to the consequences of morphological differences (such as being able to deploy a precision grasp). We compared two species of New World monkeys that differ in their tool use abilities and manual dexterity: squirrel monkeys, Saimiri sciureus (less dexterous with little evidence for tool use) and tufted capuchins, Sapajus apella (more dexterous and known tool users). The monkeys were presented with baited cups in an untrained food extraction task. Consistent with the morphological constraint hypothesis, squirrel monkeys frequently showed second-order motor planning by inverting their grasp when picking up an inverted cup, while capuchins frequently deployed canonical upright grasping postures. Findings suggest that the lack of ability for precision grasping may elicit more consistent second-order motor planning, as the squirrel monkeys (and other species that have shown a high rate of second-order planning) have fewer means of compensating for inefficient initial postures. Thus, the interface between morphology and motor planning likely represents an important factor for understanding both the ontogenetic and phylogenetic origins of sophisticated motor-planning abilities.

The Interface Between Morphology and Action Planning: a Comparison of Two Species of New World Monkeys

Recent research with several species of nonhuman primates suggests sophisticated motor-planning abilities observed in human adults may be ubiquitous among primates. However, there is considerable variability in the extent to which these abilities are expressed across primate species. In the present experiment, we explore whether the variability in the expression of anticipatory motor-planning abilities may be attributed to cognitive differences (such as tool use abilities) or whether they may be due to the consequences of morphological differences (such as being able to deploy a precision grasp). We compared two species of New World monkeys that differ in their tool use abilities and manual dexterity: squirrel monkeys, Saimiri sciureus (less dexterous with little evidence for tool use) and tufted capuchins, Sapajus apella (more dexterous and known tool users). The monkeys were presented with baited cups in an untrained food extraction task. Consistent with the morphological constraint hypothesis, squirrel monkeys frequently showed second-order motor planning by inverting their grasp when picking up an inverted cup, while capuchins frequently deployed canonical upright grasping postures. Findings suggest that the lack of ability for precision grasping may elicit more consistent second-order motor planning, as the squirrel monkeys (and other species that have shown a high rate of second-order planning) have fewer means of compensating for inefficient initial postures. Thus, the interface between morphology and motor planning likely represents an important factor for understanding both the ontogenetic and phylogenetic origins of sophisticated motor-planning abilities. (C) 2013 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

DEVELOPMENT OF A HUMANOID ROBOT ARM FOR USE IN URBAN ENVIRONMENTS

The Bucknell Humanoid Robot Arm project was developed in order toprovide a lightweight robotic arm for the IHMC / Bucknell University bipedal robot that will provide a means of manipulation and facilitate operations in urban environments. The resulting fabricated arm described in this thesis weighs only 13 pounds, and is capable of holding 11 pounds fully outstretched, lifting objects such as tools, and it can open doors. It is also capable of being easily integrated with the IHMC / Bucknell University biped. This thesis provides an introduction to robots themselves, discusses the goals of the Bucknell Humanoid Robot Arm project, provides a background on some of the existing robots, and shows how the Bucknell Humanoid Robot Arm fits in with the studies that have been completed. After reading these studies, important items such as design trees and operational scenarios were completed. The completion of these items led to measurable specifications and later the design requirements and specifications. A significant contribution of this thesis to the robotics discipline involves the design of the actuator itself. The arm uses of individual, lightweight, compactly designed actuators to achieve desired capabilities and performance requirements. Many iterations were completed to get to the final design of each actuator. After completing the actuators, the design of the intermediate links and brackets was finalized. Completion of the design led to the development of a complex controls system which used a combination of Clanguage and Java.

The Expression Of Motor Planning In Squirrel Monkeys (Saimiri sciureus) And Brown Capuchins (Cebus apella)

Multiple recent studies provide evidence that both human and nonhuman primates possess motor planning abilities. I tested for the demonstration of motor planning in two previously untested primate species through two experiments. In the first experiment, I compared the extent to which squirrel monkeys (Saimiri sciureus) and brown capuchins (Cebus apella) plan their movements in a grasping task. Individuals were presented with an inverted cup that required being turned and held upright in order to extract a food reward from the inside of the cup. This task was most efficiently solved by using an initially awkward inverted grasp that affords a comfortable hand and arm orientation at the end of the movement (known as end-state comfort). While certain individuals from both species exhibited end-state comfort, many of the capuchins never demonstrated this type of motor planning. Furthermore, the squirrel monkeys used the efficient grasp significantly more than the capuchins. In the second experiment, I presented the capuchins with another grasping task to test if they would express motor planning abilities in a different context. Here, the capuchins were offered a dowel that was baited on either the left or right end. A radial grasp with the thumb pointing towards the baited end was considered to be the most efficient grasp because it afforded a comfortable final position. The capuchins switched hands and used an overhand radial grasp on the dowel significantly more often than not, thus demonstrating motor planning in this task. The grasps typically utilized by these two closely related species differ considerably in that capuchins are capable of exercising precision grips, whereas squirrel monkeys are limited to whole-handed power grips. Moreover, unlike capuchins, squirrel monkeys are not particularly dexterous nor are they capable of precise manipulative actions. It is therefore more beneficial for squirrel monkeys to plan their movements efficiently because they are less capable of compensating for inappropriate initial grasps. Due to the appreciable variability in the expression of motor planning skills across species, I proposed that morphological constraints might explain the observed discrepancies in movement planning among different primate species.