Learning the invariants of a perceptual motor skill

The concept of invariant relative timing has typically been associated with the concept of a generalized motor programme. The present study approaches the phenomenon of invariant relative timing from the perspective of learning. The underlying question of concern for this study was, "What is learned." The specific question was whether relative timing is one of the essential properties of movement that is learned during skill acquisition. In the present experiment, subjects were given extensive practice in learning to track and reproduce a criterion waveform using a joystick control for their response. In order to test whether subjects learn the relative timing of a movement, they were transferred to tracking waveforms that were identical to the criterion in terms of relative timing, but different in terms of absolute timing. Measurements were taken on all waveforms in two conditions: (a) in a pursuit tracking condition where subjects were temporally constrained by the stimulus, and (b) in a reproduction condition where subjects' timing was not constrained. The outcome from both conditions gives support to the idea that humans learn invariant relative timing during the acquisition of a motor skill.     

Early lexical development in children with focal brain injury

Early lexical development in 27 children with focal brain injury was studied cross-sectionally and longitudinally. Data were obtained from children between 12 and 35 months of age who acquired their lesion prenatally or within the first 6 months of life. Results for the group as a whole provide clear evidence for delays in lexical comprehension and production, and for a larger number of comprehension/production dissociations than would be expected by chance. In addition, a significant number of children were observed having unusual difficulty mastering predication and/or using an atypically high proportion of closed class words (suggesting reliance on holistic/formulaic speech). Analyses by lesion type revealed no effect of lesion size. Analyses according to side of lesion revealed that children with right-hemisphere damage produced a higher proportion of closed class words, suggesting heavy reliance on well-practiced but under-analyzed speech formulae. Children with left-hemisphere damage were slightly better in comprehension than children with right-hemisphere damage. In addition, left posterior lesions were associated with greater delays in expressive language, and delays were more protracted in children with left posterior damage. No differential effects of left posterior damage were found for lexical comprehension.     

A crosslinguistic study of grammaticality judgments in Broca's aphasia

Crosslinguistic studies of sentence comprehension and production in Broca's aphasia have yielded two complementary findings: (1) grammatical morphology appears to be more impaired than word order principles in every language studied, but (2) the degree to which grammatical morphology is retained by aphasic patients depends upon the "strength" or importance of those morphemes in the patient's premorbid language. In an earlier study comparing violations of word order and agreement, we found that English-speaking Broca's aphasics showed greater sensitivity to errors of ordering than to errors of agreement, providing further evidence for the selective vulnerability of morphology. However, because English is a rigid word order language with a relatively weak inflectional system, it could be argued that word order is resilient to brain damage because it is the strongest source of information in this language. The present study compared the performance of English-speaking Broca's aphasics and normal controls with their Italian counterparts in the same grammaticality judgment experiment. Four predictions relating to our previous work were confirmed. (1) Italian aphasics, like their English-speaking counterparts, showed general preservation of grammatical knowledge and (2) they were able to use this knowledge in an "on-line" fashion. (3) Within each language, Broca's aphasics showed greater impairment in their ability to recognize errors of morphological selection (i.e., agreement) compared with errors made by moving the same words to an incorrect position downstream. Nevertheless (4), crosslinguistic differences observed in previous studies of comprehension and production were also observed in this grammaticality judgment task: a processing advantage for agreement errors in Italian normals and aphasics, and a processing advantage for ordering errors in English normals and aphasics.     

The influence of positive and negative reinforcement on selective attention in the rat

In Experiments 1 and 2 rats were trained under two multiple schedules of reinforcement. In one, bar pressing during a tone-light compound stimulus was reinforced under a variable-interval food reinforcement schedule. In the other multiple schedule, bar pressing avoided grid shock on a free-operant schedule. In both multiple schedules, a discrimination was maintained by an extinction schedule that was operative during the absence of the tone-light compound. In Experiments 1 and 2 the intensity of the tone-light compound was manipulated over three levels. Subsequent extinction tests revealed that light was attended to, almost exclusively of the tone, when food reinforcement had maintained bar pressing. On the other hand, the tone gained considerable attentional control under the shock avoidance schedule. This stimulus-reinforcer interaction was maintained for all three levels of the compound intensity. In Experiment 3 it was investigated whether this interaction was associative by presenting shock during the absence of the tone-light compound when food reinforcement maintained responding, and food during the absence of the compound when shock avoidance maintained responding. Since both food and shock were presented during a single session for both schedules, nonassociative effects of the reinforcing stimuli were equivalent across the schedules. Nevertheless, the stimulus-reinforcer interaction was maintained, indicating that the interaction was an associative effect.     

The shifting salience of valence and instrumentality in the prediction of perceived effort,satisfaction and turnover

The role of valence and instrumentality was examined in predicting three work-related criteria in a military setting: satisfaction, perceived effort, and turnover. A total of 323 enlisted men responded to desirability and instrumentality scales for each of four categories of performance outcomes: extrinsic rewards, personal fulfillment, recognition, and autonomy. Multiple regression analyses indicated that the different outcome types varied substantially in their relationship to the criteria, ranging from strongly positive to no relationship to strongly negative. Furthermore, the salience of valences and instrumentalities changed as a function of the criterion being predicted in a manner not deducible from current expectancy-valence models. Several implications of the results were discussed in terms of assumptions underlying general expectancy-valence approaches to motivation.This research was supported in part by Grant DAHC19-77-G0017 to New York University (Samuel Shiflett, principal investigator) from the Army Research Institute for the Behavioral and Social Sciences. This work was conducted while the authors were members of the Army Research Institute. The interpretations and opinions expressed herein are those of the authors and do not necessarily reflect the opinions or policies of the Department of the Army or the Department of Defense. The authors gratefully acknowledge the support and assistance of John Turney at various stages of the project.     

Self-image formation in adopted children: The environment within

Adoption of a child is an event in which a number of crises have converged. Both the biologic and adoptive families have contributed their failures and crises, and the subsequent interpretations of these by the adopted child can lead to polarized themes of goodness and badness. The absence of the biologic parents and of a coherent history reinforces the tendency to splitting. This paper explores these operations and raises questions about prevailing adoption practices.Paper presented at Spence-Chapin Symposium on Identity Problems of Children in Non-Nuclear Families, April 11, 1981.     

The relationship between sighting dominance and the fading of a stabilized retinal image

The fading of a stabilized retinal image in the sighting and the nonsighting dominant eye was studied using the Haidinger’s brush target. Reaction time to the complete disappearance of the stabilized image was significantly longer when the target was input to the sighting eye. The greater persistence of stabilized targets in the sighting eye suggests possible differences in the neural channels from the two eyes or processing differences in the two monocular channels that are related behaviorally to eye dominance.     

A truth-conditional formulation of Karttunen's account of presupposition

Karttunen's seminal 1973 article Presuppositions of compound sentences, lays the groundwork for the elegant and fruitful theory of this subject which he subsequently presented in (1974). In (1973, pp. 185–8), however, he fallaciously argued that the regularities he discovered concerning the behavior of and, or, and if ... then in English cannot be embodied in any three-valued logic giving a truth-functional interpretation to these connectives. The present paper refutes Karttunen's argument by exhibiting an interpretation with the desired properties, and shows further how the full articulation of his 1974 system can be developed naturally within a truth-conditional semantics for English if bivalence is abandoned — contrary to what Karttunen expected.