Vibrotactual choice reaction time,tactile receptor systems and ideomotor compatibility

In most of the literature on human performance the results of an experiment by Leonard (1959) are quoted as the most outstanding example of perfect S-R-compatibility. In that experiment the fingertips were stimulated by a 50 Hz vibration; the vibrating armature had to be depressed and the reaction times of the right index finger were recorded. The reaction time was found not to increase with an increasing number of tactual choices. In experiment 1 of the present study, also applying 50 Hz vibrations, the reaction times of other fingers were also reported. In addition the response stimulus interval (RSI) was varied. Leonard's results were not replicated: reaction time increased with the number of tactual choices at all levels of RSI. In experiment 2 the frequency and amplitude of vibration were systematically varied and it turned out that these variables could account for the differences between the results found. An increase in reaction time with the number of tactual choices was found with weak vibrations, but not with strong vibrations. The differences in reaction time patterns appeared to be caused by differences in tactile receptor systems (i.e. the non-Pacini versus the Pacinian system). It was concluded that the concept of S-R-compatibility did not cover the pattern of results but that the concept of ideomotor compatibility did.     

Mechanisms of developmental change in infant categorization

Computational models are tools for testing mechanistic theories of learning and development. Formal models allow us to instantiate theories of cognitive development in computer simulations. Model behavior can then be compared to real performance. Connectionist models, loosely based on neural information processing, have been successful in capturing a range of developmental phenomena, in particular on-line within-task category learning by young infants. Here we describe two new models. One demonstrates how age dependent changes in neural receptive field sizes can explain observed changes in on-line category learning between 3 and 10 months of age. The other aims to reconcile two conflicting views of infant categorization by focusing on the different task requirements of preferential looking and manual exploration studies. A dual-memory hypothesis posits that within-task category learning that drives looking time behaviors is based on a fast-learning memory system, whereas categorization based on background experience and assessed by paradigms requiring complex motor behavior relies on a second, slow-learning system. The models demonstrate how emphasizing the mechanistic causes of behaviors leads to discovery of deeper, more explanatory accounts of learning and development.     

The Frequency of Suicide in Individual Danish Birth Cohorts, 1922–1991

In recent years many suicidologists have based their epidemiological studies on suicide on theories assuming that people born within the same period of time will follow the same suicidal patterns throughout their lives, and that variations in the annual rate of suicide will, therefore, reflect systematic differences between cohorts. Cohort analysis carried out on Danish data showed, however, that although some differences could be found as to the course of events during the life span of the cohorts and also when the material was adjusted for sex, no significant differences could be found between various birth cohorts in the total rates of suicide. The authors argue that the reason for this is that a cohort effect is only one of three dimensions of an analytical tool, namely, Age–Period–Cohort (APC) analysis, and that the balance between the three effects changes over time.     

Neo‐pragmatism,Representationalism and the Emotions

This paper offers a neo‐pragmatist account of the representational character of the emotions, for those emotions that have such a character. Put most generally, neo‐pragmatism is the view that language should not be conceived primarily in terms of a robust relation of reference to or representation of antecedently given objects and properties. Rather, we should view it as a social practice that lets us do various quite different sorts of things. One of those things might be called ‘assessing representational accuracy’, but this need not be thought of in terms of a metaphysically heavyweight relation. In applying neo‐pragmatist techniques to the domain of the emotions, the result will be an alternative to currently popular accounts that individuate emotions partly in terms of what they represent. This alternative continues to allow us to use representational language in connection with some emotions. And it also helps to explain the awkwardness of representational talk in connection with other emotions: an awkwardness that was always a liability of monolithic representationalist views.     

Awareness Luck

Nagel’s constitutive moral luck is one important type of moral luck, but discussions of it have tended to focus on temperament. Luck in how aware a person is of morally relevant aspects of her situation—awareness luck—though similar in some ways, also raises different issues. Luck in temperament impacts how difficult a person finds it to behave well, while awareness luck impacts whether she even recognizes that the situation is making a moral demand on her. For this reason, awareness luck raises some unique challenges for those who would deny the existence of moral luck.     

Curiosity‐based learning in infants: a neurocomputational approach

Infants are curious learners who drive their own cognitive development by imposing structure on their learning environment as they explore. Understanding the mechanisms by which infants structure their own learning is therefore critical to our understanding of development. Here we propose an explicit mechanism for intrinsically motivated information selection that maximizes learning. We first present a neurocomputational model of infant visual category learning, capturing existing empirical data on the role of environmental complexity on learning. Next we “set the model free”, allowing it to select its own stimuli based on a formalization of curiosity and three alternative selection mechanisms. We demonstrate that maximal learning emerges when the model is able to maximize stimulus novelty relative to its internal states, depending on the interaction across learning between the structure of the environment and the plasticity in the learner itself. We discuss the implications of this new curiosity mechanism for both existing computational models of reinforcement learning and for our understanding of this fundamental mechanism in early development.     

Does prism adaptation affect visual search in spatial neglect patients: A systematic review

Prism adaptation (PA) is a widely used intervention for (visuo‐)spatial neglect. PA‐induced improvements can be assessed by visual search tasks. It remains unclear which outcome measures are the most sensitive for the effects of PA in neglect. In this review, we aimed to evaluate PA effects on visual search measures. A systematic literature search was completed regarding PA intervention studies focusing on patients with neglect using visual search tasks. Information about study content and effectiveness was extracted. Out of 403 identified studies, 30 met the inclusion criteria. The quality of the studies was evaluated: Rankings were moderate‐to‐high for 7, and low for 23 studies. As feature search was only performed by five studies, low‐to‐moderate ranking, we were limited in drawing firm conclusions about the PA effect on feature search. All moderate‐to‐high‐ranking studies investigated cancellation by measuring only omissions or hits. These studies found an overall improvement after PA. Measuring perseverations and total task duration provides more specific information about visual search. The two (low ranking) studies that measured this found an improvement after PA on perseverations and duration (while accuracy improved for one study and remained the same for the other). This review suggests there is an overall effect of PA on visual search, although complex visual search tasks and specific visual search measures are lacking. Suggestions for search measures that give insight in subcomponents of visual search are provided for future studies, such as perseverations, search path intersections, search consistency and using a speed–accuracy trade‐off.