When Ears Drive Hands: The Influence of Contact Sound on Reaching to Grasp

Background Most research on the roles of auditory information and its interaction with vision has focused on perceptual performance. Little is known on the effects of sound cues on visually-guided hand movements. Methodology/Principal Findings We recorded the sound produced by the fingers upon contact as participants grasped stimulus objects which were covered with different materials. Then, in a further session the pre-recorded contact sounds were delivered to participants via headphones before or following the initiation of reach-to-grasp movements towards the stimulus objects. Reach-to-grasp movement kinematics were measured under the following conditions: (i) congruent, in which the presented contact sound and the contact sound elicited by the to-be-grasped stimulus corresponded; (ii) incongruent, in which the presented contact sound was different to that generated by the stimulus upon contact; (iii) control, in which a synthetic sound, not associated with a real event, was presented. Facilitation effects were found for congruent trials; interference effects were found for incongruent trials. In a second experiment, the upper and the lower parts of the stimulus were covered with different materials. The presented sound was always congruent with the material covering either the upper or the lower half of the stimulus. Participants consistently placed their fingers on the half of the stimulus that corresponded to the presented contact sound. Conclusions/Significance Altogether these findings offer a substantial contribution to the current debate about the type of object representations elicited by auditory stimuli and on the multisensory nature of the sensorimotor transformations underlying action

The development and initial validation of the Supervise Cognitive-Developmental Profile Questionnaire

Systemic Cognitive-Developmental Supervision (SCDS) (Rigazio-DiGilio, 1997a; Rigazio-DiGilio & Anderson, 1994; Rigazio-DiGilio, Daniels, & Ivey, 1997) is a coconstructive model of supervision that is developmental, integrative, and culturally sensitive. SCDS is an alternative supervision model that provides a number of advantages to the practice of supervision. ^ SCDS has been well received (O\u27Byrne & Rosenberg, 1998) and clinically explored (Rigazio-DiGilio & Anderson, 1991); however, the model has not been empirically evaluated. To achieve this end, the researcher designed two studies to construct and examine the initial validity of a paper-and-pencil measure designed to assess supervisee development as defined by SCDS. In the Study 1, a set of items was generated and submitted to a series of content validity trials. Once the final pool of items was assembled, the questionnaire was mailed to a large, national sample of family therapists. Responses were factor analyzed to estimate the psychometric properties of the measure and to examine initial construct validity evidence. ^ In Study 2, a sample of training therapists completed the revised paper-and-pencil measure, an interview protocol designed to assess the predominant cognitive-developmental orientations, and measures assessing conceptual and intervention skills. Supervisors working with these therapists completed measures assessing the training therapists\u27 intervention and relationship skills. Concurrent validity was examined by comparing scores from the paper-and-pencil measure with ratings of the interview protocol. Scores from the paper-and-pencil measure also were compared with scores of clinical conceptual skills, intervention skills, and relationship skills to gather further evidence of construct validity. ^ Overall, the results were mixed. The findings suggest that there is some promise in capturing cognitive developmental-profile using a paper-and-pencil measure. The findings also suggest that further empirical investigations with the interview protocol to measure profiles would make valuable contributions to the field. Recommendations and suggestions for future research are provided.

Can you hear the shape of a drum?

Kac (1966) first poised the question of whether spectral data radiating from vibrating plates could be rich enough to specify the geometry of the plates. Recently, mathematical proofs have shown the existence of isospectral companions-manifolds of differing geometries that produce identical spectra-leading some to conclude that the perception of manifold shape based on spectral data may not be possible (e.g. Gordon & Webb, 1995). In six experiments, the present dissertation examines this issue by asking human participants to hear the geometric dimensions of thin, isotropic plates set into free vibration. Experiments 1, 2, and 5 revealed that the perceived height and width of thin rectangles of various material compositions and constant surface area are a single-valued function of G, the invariant parameter of the two-dimensional wave equation. Experiments 3 and 6 revealed that the geometry of thin circles, triangles, and rectangles of a variety of material compositions are perceptible by hearing. Lastly, Experiment 4 revealed that the perception of hardness of a variety of materials is also a function of G. These results are discussed in the context of a general theory of shape perception and the specificational link between perception and the physical properties of the perceived world.