Task dynamics and resource dynamics in the assembly of a coordinated rhythmic activity.

Task dynamics corresponding to rhythmic movements emerge from interactions among dynamical resources composed of the musculature, the link segments, and the nervous and circulatory systems. This article investigated whether perturbations of interlimb coordination might be effect over circulatory and nervous elements. Stiffness of wrist-pendulums oscillated at a common tempo and at 180 degrees relative phase was perturbed through the use of tonic activity about an ankle. Left and right stiffnesses, the common period, and the phase relation all changed. Stiffnesses increased with ankle torque in proportion to the wrist's inertial load. Despite different changes in stiffness at the two wrists, isochrony was preserved. The stability was shown to be consistent with the proportionality of changes in stiffness to the inertial loads. The phase departed from antiphase in proportion to the asymmetry of inertial loads. The size of departures decreased with increasing ankle torque. An account was developed in terms of muscular, circulatory, and nervous functions.     

On the spread of semantic excitation

Summary Access to word-representations in memory was studied in two experiments. A lexical decision paradigm was used in both: Ss had to decide whether a string of letters shown to them was a word or a nonword. Decision time was the main dependent variable. Independent variables were context-similarity and context-intensity. The former is defined in terms of the categorical relationship that holds between a set of context-words and a subsequently presented test-word. The latter is defined by the number of highly related context-words, all sampled from a small semantic subcategory, that preceded the test-stimulus. In theory, the presentation of the context-words generates semantic excitation that spreads over memory and activates other memory representations. Differences in mean decision time, as a function of experimental conditions, are attributed to differences in the activation of test-words. Two hypotheses about the course or gradient of excitation-spread in lexical memory were studied. The results indicate that a simple spread-of-excitation hypothesis as proposed by Meyer, Schvaneveldt and Ruddy (1972, 1974) is sufficient to account for the data. For the conditions studied in the experiments, there was no reliable evidence of inhibitory processes that confine spread of excitation to a small region of lexical memory.This paper reports work that was conceived and begun at Stanford University, Calif., USA, where the author spent a year as a postdoctoral fellow. The fellowship was made possible by the Deutsche Forschungsgemeinschaft, Bad Godesberg, West Germany, Grant Schm 350/1. I thank Prof. Richard G. Atkinson and Dr. Stephan Monsell for discussing aspects of this work with me. I further thank Paul Matthews for introducing me to the art of running computerized experiments.     

Eye movements of monkey observers viewing vocalizing conspecifics

Primates, including humans, communicate using facial expressions, vocalizations and often a combination of the two modalities. For humans, such bimodal integration is best exemplified by speech-reading - humans readily use facial cues to enhance speech comprehension, particularly in noisy environments. Studies of the eye movement patterns of human speech-readers have revealed, unexpectedly, that they predominantly fixate on the eye region of the face as opposed to the mouth. Here, we tested the evolutionary basis for such a behavioral strategy by examining the eye movements of rhesus monkeys observers as they viewed vocalizing conspecifics. Under a variety of listening conditions, we found that rhesus monkeys predominantly focused on the eye region versus the mouth and that fixations on the mouth were tightly correlated with the onset of mouth movements. These eye movement patterns of rhesus monkeys are strikingly similar to those reported for humans observing the visual components of speech. The data therefore suggest that the sensorimotor strategies underlying bimodal speech perception may have a homologous counterpart in a closely related primate ancestor.     

The structure of frontoparallel haptic space is task dependent

In three experiments, we investigated the structure of frontoparallel haptic space. In the first experiment, we asked blindfolded participants to rotate a matching bar so that it felt parallel to the reference bar, the bars could be at various positions in the frontoparallel plane. Large systematic errors were observed, in which orientations that were perceived to be parallel were not physically parallel. In two subsequent experiments, we investigated the origin of these errors. In Experiment 2, we asked participants to verbally report the orientation of haptically presented bars. In this task, participants made errors that were considerably smaller than those made in Experiment 1. In Experiment 3, we asked participants to set bars in a verbally instructed orientation, and they also made errors significantly smaller than those observed in Experiment 1. The data suggest that the errors in the matching task originate from the transfer of the reference orientation to the matching-bar position.     

Sleep,activity, temperature,and performance: Techniques for long-term monitoring in the mouse

This paper describes a test chamber, a food acquisition task, and a training procedure for the long-term testing of an implanted mouse in a circadian rhythm experiment. For the training phase, a special-purpose controller is provided to a single cage. For the experimental phase, behavioral, electrophysiological, and environmental measures are collected by means of a mini-computer.     

Long-term retention of a theatrical script by repertory actors: the role of context.

Four actors were requested to perform Sartre's No Exit after a retention interval of more than 5 months. Their recall of the play was studied either with the spatial and visual contextual cues normally available during a performance or without such cues. Total recall was still considerable, equalling 85%. The number of paraphrases of, and inferences on, the original text was however quite large (32%), suggesting that the actors had learned their lines according to their meaning rather than as a result of rote memorisation. The context manipulation showed that actors' recall is facilitated by the availability of spatial-visual information, but only to a limited extent. The relative importance of textual and contextual cues in the long-term retention of a play is discussed.     

Concurrent therapies: a model for collaboration between psychoanalysts and other therapists

Many psychoanalysts treat individuals who are simultaneously in couples therapy or whose partners are in individual therapy. If such cases stall, some analysts may seek consultation from a colleague, though most have accepted the tacit historical prohibition against communication between therapists treating members of the same family. Experience, however, suggests that a certain form of communication between such therapists can have a powerfully enhancing effect on the concurrent therapies. After a review of the literature, the advantages, disadvantages, and impediments to collaborative cross-communication are examined. A model is then presented for use in ongoing discussion between therapists, and is illustrated with two clinical examples. The proposed model centers on the transference-countertransference configurations within the therapeutic field, and serves as an organizer highlighting areas for discussion.