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At issue in the present series of experiments was the ability to prospectively perceive the action-relevant properties of hand-held tools by means of dynamic touch. In Experiment 1, participants judged object move-ability. In Experiment 2, participants judged how difficult an object would be to hold if held horizontally, and in Experiments 3 and 4, participants rated how fast objects could be rotated. In each experiment, the first and second moments of mass distribution of the objects were systematically varied. Manipulations of wielding speed and orientation during restricted exploration revealed perception to be constrained by (a) the moments of mass distribution of the hand-tool system, (b) the qualities of exploratory wielding movements, and (c) the intention to perceive each specific property. The results are considered in the context of the ecological theory of dynamic touch. Implications for accounts of the informational basis of dynamic touch and for the development of a theory of haptically perceiving the affordance properties of tools are discussed., ((c) 2010 APA, all rights reserved.)

Previous work has indicated that there may be a positive relationship between the duration and extent of inspiration and the length of an upcoming utterance. However, none of that work has uniquely implied a role of planning. We attempted to avoid some of the alternative explanations by forcing subjects to utter single sentences ranging in length from 5 to 82 syllables (mean of 27), after inspiring fully and then expiring down to a set level before uttering the sentence. For all 3 subjects, there was a significant positive relationship between utterance length and inspiration duration, regardless of whether inspiration was measured physiologically or acoustically. The 2 subjects with the higher correlations in the articulatory measures also expended air more quickly during the shorter sentences than longer ones, while the other subject had no correlation with exhalation rate. Complexity of the sentence, calculated as the number of clauses in the sentence, did not affect inspiration duration. The individual differences need further investigation, but there is a positive correlation between the duration of the sentence to be said and the inspiration before it when the speaker is required to read sentences while using only one breath.

When an object is held and wielded, a time-invariant quantity of the wielding dynamics is the inertia tensor Iij. Examination of Iij as a function of different locations at which a cylindrical object is grasped revealed that the off-diagonal components of Iij--the products of inertia--related most systematically to grip position. In 3 experiments, Ss wielded an occluded rod held at an intermediate point along its length and reproduced, with the other hand, the felt grip position on a visible rod. In Experiment 1, the wielded rods were homogeneous; in Experiments 2 and 3, weights were added on either side of the grasp, with different manners of grasp contrasted in Experiment 3. In all 3 experiments, perceived hand position was predicted by Iij. Discussion was focused on the role of Iij's eigenvalues in perceiving the magnitudes of objects and Iij's eigenvectors in perceiving hand-object relations (e.g., position of grasp).

Can humans, like other animals, perceive distance by mechanical vibrations transmitted in a solid medium? In seven experiments, subjects perceived the distances from the hand of occluded metal disks attached to a taut nylon strand. Mechanical waves were initiated at the hand by the subject or at the disk by the experimenter. The results of Experiments 1 and 2 showed that perceived distance was linearly dependent on object distance with or without practice. The results of Experiments 3 and 4 revealed an inverse dependency of perceived distance on strand tension. In Experiment 5, a constant difference in perceived distance between vertical and horizontal strand manipulations was found. The results of Experiments 6 and 7 showed that distance was perceptible when the mechanical wave was not initiated by the subject. The informational basis for this haptic spatial ability was sought in the dynamics expressed by the one-dimensional wave equation, specifically, in the constants relating strand forces to strand motions.