Grasp posture planning during multi-segment object manipulation tasks — Interaction between cognitive and biomechanical factors

The present study examined adaptations in the planning of initial grasp postures during a multi-segment object manipulation task. Participants performed a grasping and placing task that consisted of one, two, or three movement segments. The position of the targets was manipulated such that the degree of object rotation between the home and temporally proximal positions, and between the temporally proximal and distal target positions, varied. Participants selected initial grasp postures based on the specific requirements of the temporally proximal and temporally distal action segments, and adjustments in initial grasp posture depended on the temporal order of target location. In addition, during the initial stages of the experimental session initial grasp postures were influenced to a larger extent by the demands of the temporally proximal segment. However, over time, participants overcame these cognitive limitations and adjusted their initial grasp postures more strongly to the requirements of the temporally distal segment. Taken together, these results indicate that grasp posture planning is influenced by cognitive and biomechanical factors, and that participants learn to anticipate the task demands of temporally distal task demands, which we hypothesize, reduce the burden on the central nervous system.     

On Aesthetic Judgement and our Relation to Nature: Kant's Concept of Purposiveness

I offer a critical reconstruction of Kant's thesis that aesthetic judgement is founded on the principle of the purposiveness of nature. This has been taken as equivalent to the claim that aesthetics is directly linked to the systematicity of nature in its empirical laws. I take issue both with Henry Allison, who seeks to marginalize this claim, and with Avner Baz, who highlights it in order to argue that Kant's aesthetics are merely instrumental for his epistemology. My solution is that aesthetic judgement operates as an exemplary presentation of our general ability to schematise an intuition with a concept at the empirical level. I suggest that this counts as an empirical schematism. Although aesthetic judgement is not based on empirical systematicity, it can nevertheless offer indirect support for the latter in so far as it is a particular revelation of purposiveness in general.     

Perturbations in Action Goal Influence Bimanual Grasp Posture Planning

The authors examined the effects of perturbations in action goal on bimanual grasp posture planning. Sixteen participants simultaneously reached for 2 cylinders and placed either the left or the right end of the cylinders into targets. As soon as the participants began their reaching movements, a secondary stimulus was triggered, which indicated whether the intended action goal for the left or right hand had changed. Overall, the tendency for a single hand to select end-state comfort compliant grasp postures was higher for the nonperturbed condition compared to both the perturbed left and perturbed right conditions. Furthermore, participants were more likely to plan their movements to ensure end-state comfort for both hands during nonperturbed trials, than perturbed trials, especially object end-orientation conditions that required the adoption of at least one underhand grasp posture to satisfy bimanual end-state comfort. Results indicated that when the action goal of a single object was perturbed, participants attempted to reduce the cognitive costs associated with grasp posture replanning by maintaining the original grasp posture plan, and tolerating grasp postures that result in less controllable final postures.     

Development and maintenance of choice in a dynamic environment

Four pigeons were exposed to a concurrent procedure similar to that used by Davison, Baum, and colleagues (e.g., Davison & Baum, 2000, 2006) in which seven components were arranged in a mixed schedule, and each programmed a different left∶right reinforcer ratio (1∶27, 1∶9, 1∶3, 1∶1, 3∶1, 9∶1, 27∶1). Components within each session were presented randomly, lasted for 10 reinforcers each, and were separated by 10-s blackouts. These conditions were in effect for 100 sessions. When data were aggregated over Sessions 16-50, the present results were similar to those reported by Davison, Baum, and colleagues: (a) preference adjusted rapidly (i.e., sensitivity to reinforcement increased) within components; (b) preference for a given alternative increased with successive reinforcers delivered via that alternative (continuations), but was substantially attenuated following a reinforcer on the other alternative (a discontinuation); and (c) food deliveries produced preference pulses (immediate, local, increases in preference for the just-reinforced alternative). The same analyses were conducted across 10-session blocks for Sessions 1-100. In general, the basic structure of choice revealed by analyses of data from Sessions 16-50 was preserved at a smaller level of aggregation (10 sessions), and it developed rapidly (within the first 10 sessions). Some characteristics of choice, however, changed systematically across sessions. For example, effects of successive reinforcers within a component tended to increase across sessions, as did the magnitude and length of the preference pulses. Thus, models of choice under these conditions may need to take into account variations in behavior allocation that are not captured completely when data are aggregated over large numbers of sessions.     

Depression and heart rate variability in cardiac rehabilitation patients: exploring the roles of physical activity and fitness

Cardiac patients with depression have shown altered autonomic nervous system functioning, expressed as reduced heart rate variability. This may be associated with poorer physical fitness and less physical activity among depressed patients. These relationships were explored among patients enrolled in outpatient cardiac rehabilitation. 22 depressed and 22 nondepressed patients, matched for sex and age, were assessed at enrollment. The Beck Depression Inventory and structured interviews were used to measure depression. Patients completed ambulatory monitoring of ECG (i.e., Holter) and physical activity, as well as a treadmill stress test. Depression was associated with several measures of heart rate variability. Activity and fitness were lower among the depressed patients. Although exploratory, accounting for activity and fitness attenuated the relationship between depression and heart rate variability. This suggests that altered fitness and activity may help explain altered autonomic tone that characterizes patients with cardiovascular diseases who are psychologically depressed.     

Direct contact as a moderator of extended contact effects: cross-sectional and longitudinal impact on outgroup attitudes, behavioral intentions, and attitude certainty

Cross-group friendships (the most effective form of direct contact) and extended contact (i.e., knowing ingroup members who have outgroup friends) constitute two of the most important means of improving outgroup attitudes. Using cross-sectional and longitudinal samples from different intergroup contexts, this research demonstrates that extended contact is most effective when individuals live in segregated neighborhoods having only few, or no, direct friendships with outgroup members. Moreover, by including measures of attitudes and behavioral intentions the authors showed the broader impact of these forms of contact, and, by assessing attitude certainty as one dimension of attitude strength, they tested whether extended contact can lead not only to more positive but also to stronger outgroup orientations. Cross-sectional data showed that direct contact was more strongly related to attitude certainty than was extended contact, but longitudinal data showed both forms of contact affected attitude certainty in the long run.     

Art Therapy as a Healing Tool for Sub-fertile Women

Although fertility is fundamental to spiritual health, it is often taken for granted. When a desired pregnancy fails to occur, stress and grief frequently follow. Visual expression of feelings through “art therapy” has proved a powerful healing tool for women brave enough to give it a try at the McMaster University Fertility Clinic. The objective and subjective findings of this ongoing project suggest that through simple visual self-expression, stress, anxiety and hopelessness may be reduced. This form of art therapy also provides a joyful social experience of sharing with other women, who are dealing with these issues.     

A Reply to Uttl and Morin’s (2010) Commentary of

In response to a commentary provided by Uttl and Morin (2010) regarding the recent study by Hughes and Nicholson (2010), we evaluate their suggestion to modify our study’s design to reduce ceiling effects (similar to that of Rosa, Lassonde, Pinard, Keenan, &; Belin, 2008). Also, the commentators failed to take into account our data on reaction times (a measure that is arguably less affected by ceiling effects), which help substantiate our conclusions regarding self-face and self-voice recognition. This rejoinder encourages readers to consider the relevance of the ecological validity of Hughes and Nicholson’s findings.