Intermanual interactions related to movement amplitudes and endpoint locations

In almost all studies of bimanual movements with same and different amplitudes, the difference between amplitudes has been confounded with a difference between endpoint locations. The present authors varied those parameters orthogonally. In addition, they presented target locations on the surface on which the movements were produced (direct cues) and on a monitor (indirect cues). Participants' (N = 12) reaction times were longer when both amplitudes and endpoint locations differed than when they were the same. Intermanual amplitude correlations were reduced whenever 1 of the movement parameters differed for the 2 hands; only when cues were presented on the monitor was the amplitude correlation further reduced when both movement parameters were different. The results indicate that structural constraints on bimanual movements take effect on both amplitudes and endpoint locations. The relative importance of those 2 parameters is largely independent of the type of cue.     

Is young children’s recognition of pretense metarepresentational or merely behavioral? Evidence from 2- and 3-year-olds’ understanding of pretend sounds and speech

When young children observe pretend-play, do they interpret it simply as a type of behavior, or do they infer the underlying mental state that gives the behavior meaning? This is a long-standing question with deep implications for how “theory on mind” develops. The two leading accounts of shared pretense give opposing answers. The behavioral theory proposes that children represent pretense as a form of behavior (behaving in a way that would be appropriate if P); the metarepresentational theory argues that children instead represent pretense via the early concept PRETEND. A test between these accounts is provided by children’s understanding of pretend sounds and speech. We report the first experiments directly investigating this understanding. In three experiments, 2- and 3-year-olds’ listened to requests that were either spoken normally, or with the pretense that a teddy bear was uttering them. To correctly fulfill the requests, children had to represent the normal utterance as the experimenter’s, and the pretend utterances as the bear’s. Children succeeded at both ages, suggesting that they can represent pretend speech (the requests) as coming from counterfactual sources (the bear rather than the experimenter). We argue that this is readily explained by the metarepresentational theory, but harder to explain if children are behaviorists about pretense.     

Effect of bandwidth knowledge of results on the learning of a grip force control task

An experiment was conducted to investigate the persistence of the effect of "bandwidth knowledge of results (KR)" manipulated during the learning phase of performing a manual force-control task. The experiment consisted of two phases, an acquisition phase with the goal of maintaining 60% maximum force in 30 trials, and a second phase with the objective of maintaining 40% of maximum force in 20 further trials. There were four bandwidths of KR: when performance error exceeded 5, 10, or 15% of the target, and a control group (0% bandwidth). Analysis showed that 5, 10, and 15% bandwidth led to better performance than 0% bandwidth KR at the beginning of the second phase and persisted during the extended trials.     

Learning fine-grained and category information in navigable real-world space

Spatial judgments are affected by both fine-grained and categorical knowledge. We investigated whether, and how, the two forms of knowledge are learned in real-world, navigable space, as well as the time course of learning each type of knowledge. Participants were Northwestern University undergraduates who estimated the locations of buildings and other landmarks on campus. The Northwestern campus is roughly divided into three regions whose borders are not easy to discern, either from a map or by navigation. Nevertheless, students often refer to these regions linguistically and use them when making housing decisions, choosing classes, and so forth. We found that knowledge of both the fine-grained configuration of locations and the regional distinctions increased with time. However, regional influences on judgments occurred later in students’ time on campus. Consequently, computed distances across the nonexistent border between north and south campus locations became more biased with time. The results have implications for understanding how spatial representations develop in navigable environments.     

A Developmental Trajectory in Implicit Memory is Revealed by Picture Fragment Completion

Dissociations between performance on implicit and explicit tasks have often been taken as evidence that different neural structures subserve the two types of memory. One such dissociation involves developmental differences that emerge in explicit tasks, but which appear to be absent in implicit tasks. Such findings are consistent with the idea that implicit memory is subserved by a more primitive system that evolves earlier at both phylogenetic and ontogenetic levels. The present paper reviews previous studies that claimed to find evidence that implicit memory is fully developed in very young children. Issues of measurement error, ceiling effects, and insufficient power brought up questions about those studies with respect to the developmental issue. The present study compares performance on implicit (picture fragment completion) and explicit (free recall and recognition) memory tasks with groups ranging in age from 5–28 years. We find a reliable developmental trend in both implicit and explicit performance in which the former cannot be attributed to the operation ofexplicit memory processes. Thus, we conclude that implicit memory, like explicit memory, develops with age.     

Insanity and responsibility

This paper attempts to set forth, in the context of Anglo‐U.S. criminal law, the meaning of the concept of insanity, its necessary relation to absence of responsibility, and its bearing on some relevant psychiatric concepts and legal controversies. Irrationality is a distinctive and necessary (but not sufficient) condition for insanity. Irrationality consists in failure even to grasp the relevance of what is ‘essentially’ relevant. To that extent there obviously can be no responsibility. A mental makeup which renders one (who would not normally be so) substantially incapable of rational conduct constitutes insanity, and in that respect renders the person non‐responsible. Much more broadly and roughly speaking, the mind that is ill is the mind that is irrational (and hence in that respect non‐responsible).     

Election predictions: Reply

Contrary to Aubert's claim, my paper on election predictions does not seek to draw empirical conclusions from mathematical premisses alone. The empirical premiss, approximated by the continuity assumption, is that sufficiently small changes in the predicted vote will cause only small changes in the actual vote. The technical criticisms by Øfsti and Østerberg of the reaction function are answered by specifying the function's domain. Other criticisms are also answered, and the reply concludes by placing the election prediction theorem in the context of other theorizing about human expectations and outguessing phenomena.