A Perception-Action Coupling Type of Control in Long Jumping

The authors' goal was to identify the control mechanisms used by long jumpers (N = 6) to precisely position their foot at the board. In addition to the intertrial method usually used in previous research, an original method based on a trial-by-trial analysis was also implemented. If the approach to the board in long jumping encompasses two distinct sequences separated by a key step that marks the initiation of visual control, then a trial-by-trial analysis should reveal those sequences, regardless of the amount of adjustment: The step number at which regulation is initiated should be the same irrespective of the amount of adjustment. If, in contrast, a perception-action coupling mechanism operates, then the step number at which regulation is initiated should be a function of the amount of adjustment: A linear relation between those 2 variables should emerge. The results of the present study are compatible with continuous control mechanisms based on a perception-action coupling.     

Interference Effects from Observed Movement in Parkinson's Disease

Previous research has demonstrated that Parkinson's disease patients have an increased susceptibility to response conflict. In the present study, the authors investigate whether Parkinson's patients have a similar sensitivity to interference from observed movements. In all, 10 patients and 10 controls performed horizontal and vertical arm movements while watching a video of either a person performing similar movements or a moving dot. Movements were performed in the same plane (congruent) and orthogonal to the observed movement (incongruent). The off-axis variance of movements was our index of interference. Although patients tended to exhibit more off-axis variability than did controls, both groups demonstrated similar congruence effects, with greater variance in incongruent conditions. These results indicated that increased susceptibility to interference in Parkinson's disease does not extend to interference from observed movements.     

Quiet Eye Duration,Expertise, and Task Complexity in Near and Far Aiming Tasks

Skilled (n = 12) and less skilled (n = 12) billiards players participated in 2 experiments in which the relationship between quiet eye duration, expertise, and task complexity was examined in a near and a far aiming task. Quiet eye was defined as the final fixation on the target prior to the initiation of movement. In Experiment 1, skilled performers exhibited longer fixations on the target (quiet eye) during the preparation phase of the action than their less skilled counterparts did. Quiet eye duration increased as a function of shot difficulty and was proportionally longer on successful than on unsuccessful shots for both groups of participants. In Experiment 2, participants executed shots under 3 different time-constrained conditions in which quiet eye periods were experimentally manipulated. Shorter quiet eye periods resulted in poorer performance, irrespective of participant skill level. The authors argue that quiet eye duration represents a critical period for movement programming in the aiming response.     

Object processing for action across childhood

Human adults process and select the opportunities for action in their environment rapidly, efficiently, and effortlessly. While several studies have revealed substantial improvements in object recognition skills, motor abilities, and control over the motor system during late childhood, surprisingly little is known about how object processing for action develops during this period. This study addresses this issue by investigating how the ability to ignore actions potentiated by a familiar utensil develops between ages 6 and 10 years. It is the first study to demonstrate that (1) the mechanisms that transform a graspable visual stimulus into an object‐appropriate motor response are in place by the sixth year of life and (2) graspable features of an object can facilitate and interfere with manual responses in an adult‐like manner by this age. The results suggest that there may be distinct developmental trajectories for the ability to ignore motor responses triggered by visual affordances and the stimulus response compatibility effects typically assessed with Simon tasks.     

Al-Ghazali's Use of the Terms “Necessity” and “Habit” in his Theory of Natural Causality

The present article aims at analyzing the terms “necessity” (Al-darura) and “habit” (al-āda) in al-Ghazali's (1058?–?1111) theory of natural causality (Al-Sbābiah al-Tabī'īa) by answering the following question: Why does Al-Ghazali use term “habit” and negation of “necessity” with regard to natural Causality? Al-Ghazali denies causal necessity that links cause and effect since this relationship does not draw on logical rules that make it necessary. This, however, does not mean that he denies the existence of a causal relationship between things, as he recognizes its existence. He, however, denies the necessity of that relationship, as he claims that the source of causal necessity stems from a psychological emotion rather than from being inherent in things themselves. Al-Ghazali also attempts to base causal necessity on “habit” by claiming that the similarity of event A as cause and event B as effect stems from observation, repetition and the sequencing of natural phenomena. Al-Ghazali, then, endeavors to prove that science is based on expectation and assumption that draws on observation, the senses, and repetition and does not consider it as constant and absolute.     

The presence of magical thinking in obsessive compulsive disorder

Two research groups have raised the possibility that magical ideation may be a fundamental feature of obsessive-compulsive disorder. It has been proposed to underlie thought action fusion and superstitious beliefs. In this study, the Magical Ideation scale, the Lucky Behaviours and Lucky Beliefs scales, the Thought Action Fusion-Revised scale, the Padua Inventory, and the Obsessive Compulsive Inventory-Short Version were completed by 60 obsessive compulsive patients at a hospital clinic. Of all the measures, the Magical Ideation (MI) scale was found to be the most strongly related to obsessive compulsive symptoms. Large and significant relationships between MI scores and the measures of OCD were obtained even when alternative constructs (Lucky Behaviours, Lucky Beliefs, Thought Action Fusion-Revised scales) were held constant. No other variable remained significantly related to the Obsessive Compulsive Inventory-Short Version when magical ideation scores were held constant. The findings suggest that a general magical thinking tendency may underpin previous observed links between superstitiousness, thought action fusion and OCD severity.     

Tool use as a way to assess cognition: how do captive chimpanzees handle the weight of the hammer when cracking a nut?

Tool use in apes has been considered a landmark in cognition. However, while most studies concentrate on mental operations, there are very few studies of apes’ cognition as expressed in manual skills. This paper proposes theoretical and methodological considerations on movement analysis as a way of assessing primate cognition. We argue that a privileged way of appraising the characteristics of the cognitive abilities involved in tool use lies at the functional level. This implies that we focus on how the action proceeds, and more precisely, on how the functional characteristics of the task are generated. To support our view, we present the results of an experiment with five captive chimpanzees investigating the way how chimpanzees adapt to hammers of various weights while cracking nuts. The movement performed in the hammering task is analyzed in terms of energy production. Results show that chimpanzees mobilise passive as well as active forces to perform the compliant movement, that is, they modulate the dynamics of the arm/tool system. A comparison between chimpanzees suggests that experience contributes to this skill. The results suggest that in tool use, movements are not key per se, but only in as much as they express underlying cognitive processes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

On the signals underlying conscious awareness of action

To investigate whether conscious judgments of movement onset are based solely on pre-movement signals (i.e., premotor or efference copy signals) or whether sensory feedback (i.e., reafferent) signals also play a role, participants judged the onset of finger and toe movements that were either active (i.e., self initiated) or passive (i.e., initiated by the experimenter). Conscious judgments were made by reporting the position of a rotating clock hand presented on a computer screen and were then compared to the actual measured time of movement onset. In line with previous studies, judgment errors were found to be anticipatory for both finger and toe movements. There was a significant difference between judgment errors for active and passive movements, with judgments of active movements being more anticipatory than judgments of passive movements. This is consistent with a pre-movement (from here on referred to as an “efferent”) account of action awareness because premotor and efference copy signals are only present in active movements, whereas the main source of movement information in passive movements is sensory feedback which is subject to time delays of conduction (and hence predicts later judgment times for passive movements). However, judgments of active toe movement onset time were less anticipatory than judgments of active finger movement onset time. This pattern of results is not consistent with a pure efferent account of conscious awareness of action onset - as this account predicts more anticipatory judgments for toe movements compared to finger movements. Instead, the data support the idea that conscious judgments of movement onset are based on efferent (i.e., premotor, efference copy) and reafferent (i.e., feedback from the movement) components.     

Modest sociality and the distinctiveness of intention

Cases of modest sociality are cases of small scale shared intentional agency in the absence of asymmetric authority relations. I seek a conceptual framework that adequately supports our theorizing about such modest sociality. I want to understand what in the world constitutes such modest sociality. I seek an understanding of the kinds of normativity that are central to modest sociality. And throughout we need to keep track of the relations—conceptual, metaphysical, normative—between individual agency and modest sociality. In pursuit of these theoretical aims, I propose that a central phenomenon is shared intention. I argue that an adequate understanding of the distinctiveness of the intentions of individuals allows us to provide a construction of attitudes of the participants, and of relevant inter-relations and contexts that constitutes shared intention. I explain how shared intention, so understood, differs from a simple equilibrium within common knowledge. And I briefly contrast my views with aspects of views of John Searle and Margaret Gilbert.