The way in which gait is regulated to meet the demands of the terrain was investigated by analyzing the movements of skilled long jumpers during their run-up to the takeoff board. The analysis revealed that the run-up consists of two phases: (a) an initial accelerative phase, ending about 6 m from the board, during which athletes attempt to produce a stereotyped stride pattern; and (b) a zeroing-in phase, during which they adjust their stride pattern to eliminate error that has accrued. Further analysis revealed that the athletes were regulating a single gait parameter-the vertical impulse, or lift, of their steps. During the stereotyped approach phase they tried to maintain a constant impulse, thereby keeping flight and swing-through time constant. During the zeroing-in phase, they adjusted their flight times (and hence their stride lengths) by regulating the impulse of their steps. The essence of their skill thus appears to lie in the precise adjustment of the impulse toward the end of the run-up. The nature of the visual information that might be used to make the adjustments is discussed.Although research has increased our understanding of the biomechanics of locomotion and of some of the underlying neurophysiological mechanisms (Alexander &

Kinaesthesis, the sensing of body movement, which is essential for controlling activity, depends on registering the changes which accompany body movement. While there are two basic types of change—mechanical (articular, cutaneous, and vestibular) and visual—and so two potential sources of kinaesthetic information, the mechanical changes have traditionally been considered the basis of kinaesthesis, vision being considered a purely exteroceptive sense. J.J. Gibson, on the other hand, has argued that vision is a powerful kinaesthetic sense. To test this idea visual–mechanical kinaesthetic conflicts were created by moving the visible surroundings linearly forward and backward around a passively or actively moving subject. In most cases vision dominated. Therefore vision is not a purely exteroceptive sense, nor is visual kinaesthesis simply an adjunct to mechanical kinaesthesis. Vision is an autonomous kinaesthetic sense.

Factors which govern the temporal integration of spatial information were examined in a group of five experiments. A series of high-pass and low-pass spatially filtered versions of a visual scene were generated. Observers' ratings of these filtered versions of the scene for perceived image quality indicated that quality was determined both by the bandwidth of spatial information and the presence of high-spatial-frequency edge information. When sequences of three different versions of the scene were presented over an interval of 120 ms the perceived quality of the resulting composite image was determined both from the ratings of the individual components of that sequence and from the order in which these components were presented. When the order of spatial information in a sequence moved from coarse to fine detail the perceived quality of the composite image was significantly better than when the order moved from fine to coarse. This evidence of a coarse-to-fine bias in pattern integration was further investigated with a detection paradigm. The pattern of errors once again indicated that temporal integration of spatial information was superior when a coarse-to-fine mode of information delivery was employed. Taken together the data indicate that the pattern-integration mechanism has an inherent order bias and does not accumulate spatial information so efficiently when the 'natural' coarse-to-fine order is violated.

In 4 experiments the role of coarse (low-pass filtered) and fine (high-pass filtered) spatial information in guiding visual processing was studied in a same-different task. The second of a pair of sequential patterns was either a normal image or the first 100 ms was restricted to either coarse or fine information before a normal image was shown for the rest of the presentation. This 100-ms cue could be from the immediately succeeding image (relevant) or from other images in the set (irrelevant). Analysis of response times and errors showed relevant coarse-and fine-scale cues were usually equally effective, but any differences favored fine-scale versions. Irrelevant fine-scale cuing was significantly more disruptive than coarse-scale cuing. No evidence of preferential cuing by coarse-scale information occurred in any experiment.

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