Hierarchical organisation of neuro-anatomical constraints in interlimb coordination

Based on the observation that bimanual finger tapping movements tend toward mirror symmetry with respect to the body midline, despite the synchronous activation of non-homologous muscles, F. Mechsner, D. Kerzel, G. Knoblich, and W. Prinz (2001) [Perceptual basis of bimanual coordination. Nature, 414, 69-73] suggested that the basis of rhythmic coordination is purely spatial/perceptual in nature, and independent of the neuro-anatomical constraints of the motor system. To investigate this issue further, we employed a four finger tapping task similar to that used by F. Mechsner and G. Knoblich (2004) [Do muscle matter in bimanual coordination? Journal of Experimental Psychology: Human Perception and Performance, 30, 490-503] in which six male participants were required to alternately tap combinations of adjacent pairs of index (I), middle (M) and ring (R) fingers of each hand in time with an auditory metronome. The metronome pace increased continuously from 1 Hz to 3 Hz over the course of a 30-s trial. Each participant performed three blocks of trials in which finger combination for each hand (IM or MR) and mode of coordination (mirror or parallel) were presented in random order. Within each block, the right hand was placed in one of three orientations; prone, neutral and supine. The order of blocks was counterbalanced across the six participants. The left hand maintained a prone position throughout the experiment. On the basis of discrete relative phase analyses between synchronised taps, the time at which the initial mode of coordination was lost was determined for each trial. When the right hand was prone, transitions occurred only from parallel symmetry to mirror symmetry, regardless of finger combination. In contrast, when the right hand was supine, transitions occurred only from mirror symmetry to parallel but no transitions were observed in the opposite direction. In the right hand neutral condition, mirror and parallel symmetry are insufficient to describe the modes of coordination since the hands are oriented orthogonally. When defined anatomically, however, the results in each of the three right hand orientations are consistent. That is, synchronisation of finger tapping is determined by a hierarchy of control of individual fingers based on their intrinsic neuro-mechanical properties rather than on the basis of their spatial orientation.     

Configural processing and perceptions of head tilt

Configural processing is important for face recognition, but its role in other types of face processing is unclear. In the present study, participants made judgments of head tilt for faces in which the vertical position of the internal facial region was varied. We found a highly reliable relationship between inner-face position and perceived head tilt. We also found that changes in inner-face position affected the perceived dimensions of an individual unchanged facial feature: compared to control faces, nearly two-thirds of faces in which the features had been moved down were judged to have a longer nose. This finding suggests an early integration of configural and featural processing to create a stable holistic percept of the face. The demonstration of holistic processing at a basic perceptual level (as opposed to during face recognition) is important as it constrains possible models of the relationships between featural and configural processing.     

Serial recall and presentation schedule: a micro-analysis of local distinctiveness

According to temporal distinctiveness theories, items that are temporally isolated from their neighbours during presentation are more distinct and thus are recalled better. Event-based theories, which deny that elapsed time plays a role at encoding, explain isolation effects by assuming that temporal isolation provides extra time for rehearsal or consolidation of encoding. The two classes of theories can be differentiated by examining the symmetry of isolation effects: Event-based accounts predict that performance should be affected only by pauses following item presentation (because they allow time for rehearsal or consolidation), whereas distinctiveness predicts that items should also benefit from preceding pauses. The first experiment manipulated inter-item intervals and showed an effect of intervals following but not preceding presentation, in line with event-based accounts. The second experiment showed that the effect of following interval was abolished by articulatory suppression. The data are consistent with event-based theories but can be handled by time-based distinctiveness models if they allow for additional encoding during inter-item pauses.     

The time course of response suppression: no evidence for a gradual release from inhibition

Most models of serial recall postulate that recalled items are suppressed and thus temporarily rendered unavailable. Response suppression can explain several results, for example the small number of erroneous repetitions and people's reluctance to report repeated items. Although it is clear that response suppression is not permanent (thus permitting renewed recall of an item on the next trial), nothing is known about its time course. We report two experiments that measured the time course of response suppression with a multiple cued-retrieval response-deadline method. Emphasis was on the extent of repetition inhibition for lists that contained a repeated item. Regardless of whether presentation was rapid (Experiment 1; 150 ms/item) or slow (Experiment 2; 500 ms/item), (a) the standard pattern of repetition inhibition and erroneous repetitions occurred and (b) repetition inhibition remained constant across increasing retrieval time. This suggests that the release from response suppression is a discrete, list-wide effect rather than a continuous, gradual wearing off. The latter conclusion is consistent with the operation of the SOB model (Farrell & Lewandowsky, 2002) but not with models that postulate complete suppression with gradual wearing off.     

Verbalizing facial memory: criterion effects in verbal overshadowing

This article investigated the role of the recognition criterion in the verbal overshadowing effect (VOE). In 3 experiments, people witnessed an event, verbally described a perpetrator, and then attempted identification. The authors found in Experiment 1, which included a "not present" response option and both perpetrator-present (PP) and perpetrator-absent (PA) lineups, an increased reluctance to identify a person from both lineup types after verbalization. Experiment 2 incorporated a forced-choice procedure, and the authors found no effect of verbalization on identification performance. Experiment 3 replicated the essential aspects of these results. Consequently, the VOE may reflect a change in recognition criterion rather than a changed processing style or alteration of the underlying memory trace. This conclusion was confirmed by computational modeling of the data.     

Microstructure of eating behavior associated with Rorschach characteristics in obesity

The relationship between the microstructure of eating behavior and personality aspects according to the Rorschach Comprehensive System (Exner, 1991, 1993) was investigated among obese participants (N = 32). Eating behavior was measured using a computerized eating monitor, VIKTOR (Cabmek, Stockholm, Sweden), calculating initial eating rate and the eating curve. A higher initial eating rate reflecting eating drive was associated with Rorschach signs of stress overload according to the D Score and higher affective responsiveness to external stimuli seen in the Affective ratio. The stress overload may prompt eating, and affective responsiveness may be linked to appetite through a higher sensitivity to food stimuli, thus increasing eating drive. An accelerating rate of consumption during the meal was associated with intense emotionality and oral dependency, suggested by Pure C and Food responses.     

Bimanual training reduces spatial interference

The authors investigated whether training can reduce bimanual directional interference by using a star-line drawing paradigm. Participants (N = 30) were required to perform rhythmical arm movements with identical temporal but differing directional demands. Moreover, the effectiveness of part-task training in which each movement was practiced in isolation was compared with that of whole-task training in which only combined movements were performed. Findings revealed that bimanual training substantially reduced spatial interference, but unimanual training did not. The authors therefore concluded that the spatial coupling of the limbs is not implemented in a rigid way; instead, the underlying neural correlate can undergo plastic changes induced by training. Moreover, the practical implication that emerged from the present study is that athletic, musical, or ergonomic skills that require a high degree of interlimb coordination are best served by whole-task practice.     

Repercussions of transition out of elite sport on body image

The purpose of this study was to evaluate the psychological repercussions of transition out of elite sport from a bodily point of view. We hypothesized that the passage from a bodily over-investment to a more sedentary state would have an effect on body satisfaction. 16 Transitioning Athletes following the Sydney Olympic Games were compared with 16 Active Athletes two times during the transition period using the Body-Image Questionnaire of Bruchon-Schweitzer. Qualitative data in the form of interviews provided a complement to the quantitative data. Analysis yielded no significant differences 1 1/2 mo. after career termination between the two groups but showed a decrease in body satisfaction between 1 1/2 and 5 mo. after career termination for Transitioning Athletes, with a significant between-group difference at 5 mo. The Transitioning Athletes initially reported weight gain and uncertainty about their real physical capacities but also a continued social recognition that maintained body satisfaction. Over time, however, they were increasingly aware of this bodily deterioration, as ongoing exercise served as a reality test. Added to this were perceived decreases in social value as well as disturbing somatic manifestations. The result was a substantial effect on body satisfaction.     

The Timing of Intralimb Coordination

The authors examined the manner in which self-selected movement frequencies are impacted upon by repeated engagement in an intralimb coordination task and by alterations in the inertial characteristics of the limb. Twelve healthy adult volunteers rhythmically flexed and extended their elbow and wrist joints at a comfortable self-established frequency in 1 of 2 modes of coordination (in-phase and antiphase), while grasping 1 of 3 weighted dowels (no-weight condition [0.03 kg], light weight condition [0.5 kg], heavy weight condition [1.0 kg]). The movement frequencies adopted by subjects on the 3rd of 3 weekly sessions, following more than 120 experimental trials, were appreciably higher than those obtained during an initial session. The addition of mass to the system had an inconsistent influence upon the preferred frequency of movement. When subjects' limbs were loaded with what was deemed to be a light weight (0.5 kg), the movement frequencies that were adopted were indistinguishable from those selected when there was no (0.03 kg) loading of the limbs. In contrast, when subjects' limbs were loaded with a relatively heavy weight (1 kg), the resulting self-selected movement frequencies were reliably lower than when there was no loading of the limbs. The adopted frequency of movement was also influenced in a reliable fashion by the mode of coordination in which the movements were prepared. Those results are discussed with reference to mechanical and neuromuscular constraints on coordination dynamics.