Movement and focused attention: A failure to replicate

Our original goal was to explore the nature of the grouping-by-movement phenomenon reported by Driver and Baylis (1989). In their studies, distractors that moved in common with a centrally located target had a larger influence on focused-attention performance than did more proximate but stationary distractors. These results seemed particularly important since they suggested, contrary to the predictions of space-based models of attention, that attention could be allocated to noncontiguous regions of the visual field. Their results also suggested mandatory processing of stimuli with common motion. Unfortunately, we were unable to replicate this grouping-by-movement effect. In the conditions of Experiment 1 in which we replicated Driver and Baylis’s methodology, stationary distractors produced a larger response-compatibility effect than did the more distant distractors that moved in common with the target. In Experiment 2, we redundantly coded the centrally located target and the far distractors with common movement and color. However, the results were identical to those obtained in Experiment J. The stationary near distractors that appeared in a different color from the target and the far distractors produced the largest response-compatibility effect. In a final experiment, we attempted to compensate for the reduced acuity of the moving distractors by adjusting their size by a cortical magnification factor. However, even with this manipulation, we found a larger response-compatibility effect for the stationary near distractors than for the moving distant distractors. Our results suggest that subjects are capable of selectively processing a target item that moves in common with distractors.     

Hippocampal deafferentation: transplantderived reinnervation and functional recovery

A brief review is provided of the capacity of neural tissue transplants to reinnervate the deafferented hippocampus and repair functional deficits induced by the lesion. The techniques for transplantation of solid pieces of embryonic septum, locus coeruleus or raphe nuclei, or tissue suspensions of embryonic septum, to the adult rat hippocampus are described. Such grafts manifest good long-term survival, provide a good reinnervation of the hippocampus that is histochemically and biochemically appropriate and specific, can establish ultrastructural synaptic contacts with the host, and are electrophysiologically active. Rats with septal grafts manifest recovery of the capacity to learn certain aspects of radial 8-arm maze, T-maze alternation and Morris water-maze tasks. Rats with locus coeruleus grafts manifest an amelioration of lesion-induced hyperactivity. It is concluded that neural tissue transplantation provides a powerful new tool in the study of the functional organization of the hippocampus and its various neurotransmitter-specific afferent systems.     

Functional recovery following brain damage: conceptual frameworks and biological mechanisms

Mammals are well known to manifest recovery over time of many functional impairments induced by brain lesions. A brief reveiw is provided of the different conceptual frameworks within which functional recovery has been examined in the literature, and of different neurobiological mechanisms that have been proposed to account for the phenomenon. We observe that these two levels of analysis have frequently been only loosely related. Finally, a newly identified biological mechanism—compensatory collateral sprouting—is described which appears to be closely related to functional recovery in animals with hippocampal lesions, and this is proposed as a powerful new model within which to investigate further the relationship between the phenomenon of functional recovery and its underlying mechanisms.     

Testing the assumptions of exponential,additive reaction time models

Two assumptions commonly made by choice reaction time (RT) models are (1) that certain experimental tasks can be found that cause an extra processing stage to be inserted into the cognitive process and (2) that the duration of one or more processing stages is random with an exponential distribution. Few rigorous tests of either assumption exist. This paper reviews existing tests and presents several new results that can be used to test these assumptions. First, in the case in which the duration of an inserted stage is exponentially distributed, it is shown that the observable RT density functions must always intersect at the mode of the density requiring the extra processing stage. Second, when only the first assumption (Assumption 1) is made, it is shown that the cumulative RT distribution functions and, in many cases, the hazard functions must be ordered. Finally, when only Assumption 2 is assumed, it is shown that, under fairly weak conditions, the taft of the RT density function must be exponential. The first two results are applied to data from a memory scanning experiment, and the two assumptions are found to receive tentative support     

Mental shock can produce retrograde amnesia

Subjects in three experiments saw a short film of a mentally shocking event in which a young boy is violently shot in the face. Compared to other subjects who saw a nonviolent version of the same film, those who saw the mentally shocking version showed poorer retention of the details of the film. Retention was poorer whether measured by recognition or recall. Furthermore, impaired memory occurred only when the event was mentally upsetting, and not when it was merely unexpected but not upsetting. These results suggest that mentally shocking episodes may disrupt the lingering processing necessary for full storage of information in memory.     

Abortion and the death of the fetus

Abortion is conceptualized as encompassing two aspects: ending the physical dependency relationship the fetus has to the mother, and terminating the life of the fetus. Analysis of the unique nature of the mother-fetus and mother-child relationship leads to the conclusion that both the act of abortion and the pregnant woman's decision to seek the death of the fetus can be logically justified.     

Preschool peer perceptions of the behavior of hyperactive and aggressive children

To assess if preschool children can successfully identify externalizing symptomatic behaviors in their male classmates, and if these perceptions are associated with peer-rated popularity and rejection, 154 preschool boys and girls were interviewed using a peer nomination procedure. Behavioral data on the same preschool boys (N=86) were also provided by their respective teachers. Preschool children were capable of providing stable nominations of popularity, rejection, and aggression, boys and girls significantly agreed in their nominations, and these nominations were not a function of the age of the rated child, although they differed somewhat as a function of the age of the rater. Teachers and peers reflected significant convergence in ratings of hyperactivity and aggression and teacher ratings of peer problems significantly agreed with actual peer nominations of popularity and rejection. Boys nominated as aggressive were more rejected by their classmates, whereas boys nominated as hyperactive were either more popular and /or more rejected. Limited evidence for differential patterns of relationships among hyperactivity, aggression, and peer status was obtained for both the peer and teacher data.Portions of this paper were presented as part of a symposium, W. Pelham (Chair),Peer relations in hyperactive children: Diagnostic, symptomatic, and treatment consideration, at the annual meeting of the American Psychological Association, Los Angeles, August 1981. This research was supported, in part, by NIMH grant #32992 to the first author.     

A comparison of mothers' and fathers' speech to their 3-year-old sons

The language patterns of 10 mothers and 10 fathers with their firstborn 3-year-old sons were compared. Ten-minute mother-son and father-son conversations were recorded independently in the home during a free-play session with standard play mterials. The findings of this study indicate that although mothers and fathers used a similar number of utterances in conversing with their sons over a 10-minute period, their patterns of speech were different on a number of quantitative measures including MLU, MLU of five longest utterances, percent of imperatives, and percent of questions. In general, fathers' communication was viewed as more controlling and involving the child less, while mothers' communication was viewed as more child-centered and involving the child more.