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Biomedical subjects

H L Pick

Publications and source records attributed to H L Pick.

At least 19 recordsLinked to original sources
PubMed1995

Calibration of human locomotion and models of perceptual-motor organization.

People coordinate the force and direction of skilled actions with target locations and adjust the calibrations to compensate for changing circumstances. Are the adjustments globally organized (adjusting a particular action to fit a particular circumstance would generalize to all actions in the same circumstance); anatomically specific (every effector is adjusted independently of others); of functional (adjustments would generalize to all actions serving the same goal and generating the same perceptible consequences)? Across 10 experiments, changes in the calibration of walking, throwing, and turning-in-place were induced, and generalization of changes in calibration to functionally related and unrelated actions were tested. The experiments demonstrate that humans rapidly adjust the calibration of their walking, turning, and throwing to changing circumstances, and a functional model of perceptual-motor organization is suggested.

Adult↗
PubMed1995

Effects of distance on vocal intensity.

The vocal response of speakers to change of distance from a listener is in dispute. Warren (1968) found that speakers obeyed the inverse square law when compensating for distance changes; that is, they decreased their vocal intensity by 6 dB when distance was halved. However, speakers in a study of Johnson, Pick, Siegel, Cicciarelli, and Garber (1981) changed their vocal intensity by much less than 6 dB. This study was an attempt to reconcile the conflicting results and to gain better understanding of what people know implicitly about the effects of distance on intensity. Speakers in the present study significantly changed their vocal intensity to compensate for changes in distance, but by a maximum of 2.46 dB. Possible reasons for the different results are discussed.

Adult↗
PubMed1992

The role of binocular information in ball catching.

The role of binocular vision in a ball-catching task involving spatial uncertainty was examined in three experiments. In all three experiments, subjects' catching performance was evaluated during monocular and binocular viewing, in normal room lighting and in complete darkness with a luminescent ball. Subjects' performance was found to be significantly better with binocular than with monocular vision, especially under normal lighting conditions. In the second and third experiments, catching performance was evaluated in the presence of minimal visual frames, consisting of a series of light-emitting diodes (LEDs). In Experiment 2, the visual frame consisted of a single plane of LEDs, whereas in Experiment 3, the visual frame consisted of two planes of LEDs. Catching performance was found to be significantly better with the visual frame than in complete darkness, but this was true only for binocular viewing. This result supports the hypothesis that binocular convergence is used to scale perceived space and that this information enables subjects to contact the ball successfully. It was further found that postural sway varied between lighting conditions and that less sway was accompanied by higher performance. There was no effect of binocular viewing in this respect. In general, the results suggest two additive effects of viewing conditions: a direct effect of binocular vision on ball catching and an indirect effect of lighting on postural stability, which, in turn, affects catching performance.

Journal Article↗
PubMed1990

The independence of horizontal and vertical dimensions in handwriting with and without vision.

The purpose of this study was to investigate the relationship between horizontal and vertical components of handwriting production when subjects were instructed to vary the size of these components separately or together. The effect of vision on these instructed size transformations also was examined. Eight female adults participated in the experiment. The basic task was to write the words 'poppy' and 'wood' cursively five times, the first time in their normal size and then with four size transformations. These transformations--one-fourth, one-half, double, and four-times their normal size--were made under three different sets of instructions (width only, height only, both) and in two visual conditions (normal, blindfolded), for a total of six sets of five repetitions. The individual slopes (changes in actual values across the transformation values) for width and height under instructions to change both parameters were almost identical to the width and height slopes under instructions to change only the single parameter, supporting the notion of the independence of the horizontal and vertical components. Further, an analysis of these individual slopes indicated that the size transformations were significantly greater (p less than 0.05) (and closer to the instructed values) with vision than without vision.

Adult↗
PubMed1990

Children's use of frames of reference in communication of spatial location.

The frames of reference used by 4-, 6-, and 8-year-old children were studied in a spatial direction-giving task. Children were asked to specify verbally the location of a toy hidden under one of several identical cups. The child and listener sat facing each other at opposite ends of a room that had distinctive or nondistinctive landmarks proximal and distal to the hiding location. Location needed to be specified with respect to either the left-right dimension, the front-back dimension, or both. The results indicated that (1) although children's overall performance improved with age, communication about the left-right dimension was particularly difficult for 4-year-old children and showed a higher rate of improvement with age than communication about the front-back dimension; and (2) the frames of reference that children incorporated into their directions changed with age and differed for directions about the front-back and left-right dimensions. Both 4- and 6-year-old children used person references (themselves or the listener) to specify front-back relations, but only the 6-year-olds were able to compensate for their apparent difficulty in using the terms left and right by using landmarks to specify the left-right dimension. Eight-year-olds used a combination of person and landmark references in directions about both dimensions. Discrepancies between the frames of reference children used to communicate spatial location and those typically used in other spatial cognition tasks are discussed in terms of developmental and task constraints.

Attention↗
PubMed1989

Inhibiting the Lombard effect.

The Lombard effect is the tendency to increase one's vocal intensity in noise. The present study reports three experiments that test the robustness of the Lombard effect when speakers are given instructions and training with visual feedback to help suppress it. The Lombard effect was found to be extremely stable and robust. Instructions alone had little influence on the response to the noise among untrained speakers. When visual feedback correlated with vocal intensity was presented, however, subjects could inhibit the Lombard response. Furthermore, the inhibition remained after the visual feedback was removed. The data are interpreted as indicating that the Lombard response is largely automatic and not ordinarily under volitional control. When subjects do learn to suppress the effect, they seem to do so by changing overall vocal level rather than their specific response to the noise.

Feedback↗
PubMed1988

Role of visual information in ball catching.

The present study is concerned with the perceptual information about the body and space underlying the act of catching a ball. In a series of four experiments, subjects were asked to catch a luminous ball under various visual conditions. In general, catching in a normally illuminated room was contrasted with catching the luminous ball in an otherwise completely dark room. In the third and fourth experiments, intermediate conditions of visual information were included. The results suggest that it is possible to catch a ball with one hand when only the ball is visible, but performance is better when the subject has the benefit of a rich visual environment and two hands. The second experiment indicated that subject performance does improve with practice in the dark, but time spent in the darkened room itself doesn't result in a significant decrement in performance. Results of the third study suggest that vision of one's hand does not aid in the performance of this task whereas the presence of a minimal visual frame appears to aid performance. The final study examined the relation between catching performance and body sway under similar visual conditions. Results of this experiment imply that persons who exhibit relatively little postural sway in full-room lighting performed better at this catching task.

Journal Article↗
PubMed1982

Parameters of auditory feedback.

Adult speakers participated in three feedback conditions: Lombard, sidetone amplification, and delayed auditory feedback (DAF). All the procedures affected vocal intensity significantly, but only DAF caused changes in syllable rate. The three conditions did not provide equivalent data. Performance on any one of the feedback procedures was not predictive of performance on the others. Generalizations concerning auditory feedback must, therefore, take account of the particular method used and the parameter of speech studied.

Adult↗
PubMed1981

Regulation of vocal intensity in the presence of feedback filtering and amplification.

Subjects read while their voices were fed back with 0 and 20 dB of amplification. In Experiment I, feedback was returned unfiltered or low-pass filtered with cut-off frequencies of 1000, 500, and 300 Hz. Subjects decreased vocal intensity with amplified feedback when the feedback was unfiltered or low-pass filtered with cut-off frequencies of 1000 or 500 Hz. The amplification effect disappeared when the cut-off frequency was 300 Hz. In Experiment II, feedback was low-pass filtered and amplified in the presence of a steady background noise. The presence of noise potentiated the amplification effect in the unfiltered condition. When filtering was introduced and/or the cut-off frequency was lowered, the amplification effect decreased. In Experiment III, subjects heard their voices unfiltered and high-pass filtered with cut-off frequencies of 500, 1000, and 2000 Hz. The amplification effect was the same across filtering conditions. It is suggested that subjects respond differently and high- and low-pass filtering because air- and bone-conducted feedback interact differentially in these conditions. It is hypothesized that changes may be mediated by self-perception of loudness or intelligibility.

Adult↗
PubMed1980

The effects of feedback filtering on speaker intelligibility.

Subjects read intelligibility tests while hearing their voices low- or high-pass filtered. The tests were presented to listeners to assess speaker intelligibility. Feedback filtering had a variable effect on intelligibility. When speakers were permitted to increase their intensities in low-pass filtering conditions, their intelligibility also increased. Intelligibility did not increase when intensity was controlled. These results do not support the hypothesis that speakers modulate their voices in order to maintain intelligible communication with a presumed listener. IT is suggested instead that speakers alter their intensities in order to regulate the loudness of their voices in their own ears.

Adult↗
PubMed1980

Delayed auditory feedback with children.

There is a controversy in the literature concerning the effects of delayed auditory feedback (DAF) on the speech of subjects of varying ages. In the current experiment the subjects were five-year-olds, eight-year-olds, and adult speakers who performed a sentence repetition task under: 0-delay, 250, 375, 500, and 625 msec of amplified delayed auditory feedback. All subjects performed the task under normal rate instructions and under instructions to speak as rapidly as possible. A developmental pattern emerged, with the youngest children significantly more affected by the DAF than the older children or the adults. There was only weak evidence for a critical delay interval that varied according to age of the subjects. Rate instructions had essentially no effect on the DAF or age patterns.

Adult↗
PubMed1978

Intensity of guitar playing as a function of auditory feedback.

Subjects played an electric guitar while auditory feedback was attenuated or amplified at seven sidetone levels varying 10-dB steps around a comfortable listening level. The sidetone signal was presented in quiet (experiment I) and several levels of white noise (experiment II). Subjects compensated for feedback changes, demonstrating a sidetone amplification as well as a Lombard effect. The similarity of these results to those found previously for speech suggests that guitar playing can be a useful analog for the function of auditory feedback in speech production. Unlike previous findings for speech, the sidetone-amplification effect was not potentiated by masking, consistent with a hypothesis that potentiation in speech is attributable to interference with bone conduction caused by the masking noise.

Adult↗