The Role of Organization in the Learning of a Sensori-Motor Task

Two experiments investigated the ability of five- and six-month-old Guatemalan infants to discriminate human faces visually and to associate faces and voices differing in age and sex. The 32 infants in Experiment I discriminated between photographs of a man, a woman, and a seven-year-old boy. They did not, however, discriminate between photographs of two men, two women, or of two seven-year-old boys. The 24 infants in Experiment II were presented three different pairs of photographs of faces. One pair consisted of a man and a woman, another of a woman and a child, and the third of a man and a child. Voices appropriate to each pair of photographs accompanied the presentation of the visual stimulus. Looking at the woman and child seemed to be influenced by the presentation of a woman's voice and a boy's voice. Appropriate voices did not alter looking behavior with regard to the woman and man or the man and child.     

Task switching: a PDP model

When subjects switch between a pair of stimulus-response tasks, reaction time is slower on trial N if a different task was performed on trial N - 1. We present a parallel distributed processing (PDP) model that simulates this effect when subjects switch between word reading and color naming in response to Stroop stimuli. Reaction time on "switch trials" can be slowed by an extended response selection process which results from (a) persisting, inappropriate states of activation and inhibition of task-controlling representations; and (b) associative learning, which allows stimuli to evoke tasks sets with which they have recently been associated (as proposed by Allport & Wylie, 2000). The model provides a good fit to a large body of empirical data, including findings which have been seen as problematic for this explanation of switch costs, and shows similar behavior when the parameters are set to random values, supporting Allport and Wylie's proposal.     

Family Interaction as a Function of Experimental Task

To assess consistency family interaction across different experimental tasks, the present study evaluated family patterns of talking and interrupting, as elicited from discussions of a Plan Something Together Task, a set of TAT cards, and an Unrevealed Difference Questionnaire. With few exceptions, data analyses indicated that such family patterns are not altered significantly as a function of experimental tasks and, therefore, suggest considerable interactional stability across differing contexts. Characteristics of the present study (as well as related investigations of task effects) are discussed in terms of implications for future research efforts.     

Species Inegalitarianism as a Matter of Principle

Most critics of species egalitarianism point to its counter-intuitive implications in particular cases. But this argumentative strategy is vulnerable to the response that our intuitions should give way in the face of arguments showing that species egalitarianism is required by our deepest, most fundamental moral principles. In this article, I develop an argument against deontological versions of species egalitarianism on its own terms. Appealing to the fundamental moral ideal of proportionality, I show that deontological species egalitarianism is morally objectionable as a matter of principle: it is committed to treating two individuals who are extraordinarily similar in morally relevant respects drastically differently. I then illustrate how an inegalitarian account of moral standing might be incorporated into traditional moral theories in ways that make them far more promising as theories of our obligations to the non-human world.     

Neural Processing to Visual Stimuli in a Three-Choice Reaction-Time Task

Some authors have suggested that certain components of the event-related potentials (ERPs) reflect underlying stages in the discrimination process. Previous studies have shown that in an auditive three-choice reaction-time task the discrimination is accomplished as a two-stage process, with the more frequently occurring stimulus discriminated at an earlier point than the rarer stimulus and the subjects could be classified as fast and slow responders in function of their response to the most frequent of the three tones. We continuously recorded the electrocerebral activity (EEG) from the scalp and the electromyographic activity (EMG) from the responding muscles in a visual three-choice reaction-time task in 10 strictly right-handed subjects. EEG and EMG responses were subsequently analyzed off-line by aligning them by the onset of either the stimulus (stimulus-synchronized) or the response (response-synchronized). The results suggest that processes of visual stimuli evaluation and response execution are continuously integrated. The discrimination and response systems to visual stimuli is accomplished as a three-stage process, one to frequent tone, another for rare 1, and the last for rare 2. The subjects were classified as fast and slow responders in function of their response to the most frequent of the three tones.     

Family interaction Patterns as a Function of Task Characteristics1

Data from two experiments were evaluated to test the widely held assumption that family process remains essentially constant regardless of the conditions under which it occurs. Significant differences and reversals in patterns of dominance between interacting husbands and wives were obtained under different task conditions. In general, stressful tasks and tasks with structured goals elicited paternal dominance, while maternal dominance of more equalitarian patterns resulted from tasks which involved discussion of feelings and opinions. These and other task dimensions were discussed. The findings of this study generate four conclusions: prior studies must be reviewed to evaluate task effects; future researchers must systematically investigate task characteristics; researchers must exercise care in the selection of tasks in future studies; and the relationship between role behaviors and task demands must be understood in order to help meet the increasing stress impinging upon the modern family system.