David A. Rosenbaum

Cognition and Motor Processes

I Motor Control and Action Planning.- 1 Cognitivism and Future Theories of Action: Some Basic Issues.- 2 A Distributed Processing View of Human Motor Control.- 3 The Apraxias, Purposeful Motor Behavior, and Left-Hemisphere Function.- 4 A Motor-Program Editor.- 5 Eye Movement Control During Reading: The Effect of Word Units.- II Motor Contributions to Perception and Cognition.- 6 Motor Theories of Cognitive Structure: A Historical Review.- 7 Context Effects and Efferent Factors in Perception and Cognition.- 8 Saccadic Eye Movements and Visual Stability: Preliminary Considerations Towards a Cognitive Approach.- 9 Scanning and the Distribution of Attention: The Current Status of Herons Sensory-Motor Theory.- 10 The Relationship Between Motor Processes and Cognition in Tactile Vision Substitution.- III Mediating Structures and Operations Between Cognition and Action.- 11 Mechanisms of Voluntary Movement.- 12 Evaluation: The Missing Link Between Cognition and Action.- 13 Modes of Linkage Between Perception and Action.- 14 The Contribution of Vision-Based Imagery to the Acquisition and Operation of a Transcription Skill.- 15 Speech Production and Comprehension: One Lexicon or Two?.- IV Attention, Cognition, and Skilled Performance.- 16 S-Oh-R: Oh Stages! Oh Resources!.- 17 Automatic Processing: A Review of Recent Findings and a Plea for an Old Theory.- 18 Motor Learning as a Process of Structural Constriction and Displacement.- V Interactions Between Cognition and Action in Development.- 19 Cognition and Action in Development: A Tutorial Discussion.- 20 Biodynamic Structures, Cognitive Correlates of Motive Sets and the Development of Motives in Infants.- 21 Discontinuity in the Development of Motor Control in Children.- Author Index.

Posture-based motion planning: applications to grasping.

This article describes a model of motion planning instantiated for grasping. According to the model, one of the most important aspects of motion planning is establishing a constraint hierarchy--a set of prioritized requirements defining the task to be performed. For grasping, constraints include avoiding collisions with to-be-grasped objects and minimizing movement-related effort. These and other constraints are combined with instance retrieval (recall of stored postures) and instance generation (generation of new postures and movements to them) to simulate flexible prehension. Dynamic deadline setting is used to regulate termination of instance generation, and performance of more than one movement at a time with a single effector is used to permit obstacle avoidance. Old and new data are accounted for with the model.

Hierarchical control of rapid movement sequences.

Are movement sequences executed in a hierarchically controlled fashion? We first state explicitly what such control would entail, and we observe that if a movement sequence is planned hierarchically, that does not imply that its execution is hierarchical. To find evidence for hierarchically controlled execution, we require subjects to perform memorized sequences of finger responses like those used in playing the piano. The error data we obtain are consistent with a hierarchical planning as well as execution model, but the interresponse-time data provide strong support for a hierarchical execution model. We consider three alternatives to the hierarchical execution model and reject them. We also consider the implications of our results for the role of timing in motor programs, the characteristics of motor buffers, and the relations between memory for symbolic and motor information.

Grasping the meaning of words

Action affordances can be activated by non-target objects in the visual field as well as by word labels attached to target objects. These activations have been manifested in interference effects of distractors and words on actions. We examined whether affordances could be activated implicitly by words representing graspable objects that were either large (e.g., APPLE) or small (e.g., GRAPE) relative to the target. Subjects first read a word and then grasped a wooden block. Interference effects of the words arose in the early portions of the grasping movements. Specifically, early in the movement, reading a word representing a large object led to a larger grip aperture than reading a word representing a small object. This difference diminished as the hand approached the target, suggesting on-line correction of the semantic effect. The semantic effect and its on-line correction are discussed in the context of ecological theories of visual perception, the distinction between movement planning and control, and the proximity of language and motor planning systems in the human brain.

Planning macroscopic aspects of manual control

Abstract Although considerable attention has been paid to detailed features of motor performance, surprisingly little attention has been paid to the selection of macroscopic features. This paper is concerned with the selection of one such feature — whether to pick up a stick with the thumb pointed toward one end or the other when the stick is to be brought to some other location. The choice of hand orientation is found to depend on how comfortable the arm will be at the end of the bar-transport movement. In addition, the choice of hand grip depends on which hand grips were used before. The sequential effect suggests that there is a cost in selecting macroscopic movement features which can be offset by continuing with the existing strategy until feedback indicates that a change is required.

The Movement Precuing Technique: Assumptions, Applications, and Extensions

The movement precuing technique is designed to reveal the major information-processing steps that lead up to the execution of voluntary movements. The main idea in the technique is to supply the subject with partial information about the defining characteristics of a motor response and then observe how long it takes the subject to perform the response when its corresponding reaction signal is presented. On the assumption that the time to perform the response includes the time to specify those parameters that were not precued in advance, times to perform the response in different precue conditions can be used to find out whether its defining parameter values are specified in a fixed or variable order, serially or in parallel, etc. This chapter reviews the studies that have utilized the movement precuing technique. These studies have focused on aimed hand movements, finger movements, and aimed foot movements. A common finding of the studies is that the parameters of movements can be specified in a variable rather than fixed order and serially rather than in parallel, although some notable exceptions have been found. Much of the chapter is concerned with methodological variations of the precuing technique which a number of investigators have introduced.

Knowledge Model for Selecting and Producing Reaching Movements

This article presents a new model of reaching control. The aim of the model is to characterize the computations underlying the selection of coordinated motion patterns among the limb segments. When a spatial target is selected, stored postures are evaluated for the contributions they can make to the task, and a special weighted average (the gaussian average) is taken of the postures to find a single target posture. Movement to the target posture is achieved without explicit planning of the trajectory. Rather, the reaching motion is driven by error correction (reducing the discrepancy between the current and target posture) shaped by inertia. The model solves the degrees-of-freedom problem for reaching. It also allows joints to compensate automatically for reduced mobility of other joints and explains established effects of practice, speed-accuracy trade-off, and kinematics. The model can be extended to other tasks and motor subsystems because of the generality of its underlying concepts.

Time course of movement planning: selection of handgrips for object manipulation.

A goal of research on the cognitive control of movement is to determine how movements are chosen when many movements are possible. We addressed this issue by studying how subjects reached for a bar to be moved as quickly as possible from a home location to a target location. Ss generally grabbed the bar in a way that afforded a comfortable posture at the target location (the end-state comfort effect) and with the thumb toward the end of the bar that would be aligned with the target (the thumb-toward bias). The data suggested that subjects chose handgrips by retrieving instances of previous reaches, not by carrying out computations that treated candidate reaches as new behavioral events.

Where grasps are made reveals how grasps are planned: generation and recall of motor plans

The end-state comfort effect (Rosenbaum et al. 1990, 1992, 1993, 1996) predicts that people will grasp an object for transport in a way that allows joints to be in mid-range at the end of the transport. When participants in the present study took hold of a vertical cylinder to move it to a new position, grasp heights on the cylinder were inversely related to the height of the target position, as predicted by the end-state comfort effect. This demonstrates that where people grasp objects can give insight into the planning of movement. In the computational model of motor planning developed by Rosenbaum et al. (1995, 2001) it is assumed that goal postures are planned by a two-stage process of recall and generation. The distinction between recall and generation had not so far been tested. In the present study, the pattern of grasp heights in successive transports was consistent with the view that participants generated a plan the first time they moved the cylinder between two points, and that they subsequently recalled what they had done before, making small adjustments to that recalled plan. This outcome provides evidence for distinct effects of recall and generation on movement planning.

From cognition to biomechanics and back: The end-state comfort effect and the middle-is-faster effect

Consistent preferences for particular types of movement suggest criteria for movement selection. These can be important when, as is usually the case, infinitely many movements allow a task to be achieved. The experiments reported here were designed to identify the source of a strong preference observed in earlier object-manipulation studies. In those earlier studies, subjects usually grabbed objects to be moved from one location to another in a way that afforded a comfortable final posture rather than a comfortable initial posture (the end-state comfort effect). The comfortable final state usually allowed the forearm to be at or near the middle of its range of motion on the pronation-supination dimension. The hypothesis tested here was that the end-state comfort effect stemmed from an expectation that movements can be made more quickly in the middle of the pronation-supination range than at either extreme. To test this hypothesis, we asked subjects, in the first experiment, to perform a handle rotation task that demanded little or no precision and so no need to make rapid to-and-fro homing-in movements near the end of the rotation. Half the subjects did not show the end-state comfort effect, in contrast to all previous studies, where all subjects showed the effect. An incidental finding of the first experiment was that handle rotations that ended at or near the end of the range of motion took longer than handle rotations that ended at or near the middle of the range of motion. To test the latter result more carefully, we asked subjects, in Experiments 2 and 3, to oscillate the forearm as quickly as possible, either in the supination part of the forearm rotation range, in the middle part of the range, or in the pronation part of the range. As predicted, oscillation frequencies were highest in midrange, and this was true for both hands. The results as a whole have implications for the relation between cognitive psychology and biomechanics, and for human factors.