Synergies and Motor Equivalence in Voluntary Sway Tasks: The Effects of Visual and Mechanical Constraints

The authors used two analyses developed within the framework of the uncontrolled manifold hypothesis to quantify multimuscle synergies during voluntary body sway: analysis of intertrial variance and analysis of motor equivalence with respect to the center of pressure (COP) trajectory. Participants performed voluntary sway tasks in the anteroposterior direction at 0.33 and 0.66 Hz. Muscle groups were identified in the space of muscle activations and used as elemental variables in the synergy analyses. Changing mechanical and vision feedback–based constraints led to significant changes in indices of sway performance such as COP deviations in the uninstructed, mediolateral direction and indices of spontaneous postural sway. In contrast, there were no significant effects on synergy indices. These findings show that the neural control of performance and of its stability may involve different control variables and neurophysiological structures. There were strong correlations between the indices of motor equivalence and those computed using the intercycle variance analysis. This result is potentially important for studies of patients with movement disorders who may be unable to perform multiple trials (cycles) at any given task, making analysis of motor equivalence of single trials a viable alternative to explore changes in stability of actions.     

Internally driven strategy change

The behavioural analysis of normal adults solving a combinatorial game—the subtraction game—that was previously studied by Gneezy, Rustichini, and Vostroknutov (2010 Gneezy, U., Rustichini, A. and Vostroknutov, A. 2010. Experience and insight in the race game. Journal of Economic Behavior and Organization, 75: 144–155.  [Google Scholar]) allows one to identify the transition from one strategy to a novel strategy. Based on protocol analysis and debriefing, two different strategies used by participants in this task are identified and compared with behavioural measurements (reaction times, accuracy, and mouse movements). One is a (forward) exploration strategy and the other is a more complex but efficient backward induction procedure. The clear determination of the transition from the standard forward exploration strategy to a novel internally generated strategy is established by both protocol reports and behavioural measurements. It allows for the potential investigation of the underlying transition to be carried out by cognitive neuroscience methods. A set of characteristics of such transitions to internally generated novel strategies are discussed.     

Lightness effects in Delboeuf and Ebbinghaus size-contrast illusions

We examined lightness effects observed in Delboeuf and Ebbinghaus size-contrast illusions. Results of four experiments are reported. Experiment 1 was conducted with Delboeuf-like stimuli and shows that the disk that appears bigger appears either lighter or darker than the disk that appears smaller, depending on the contrast polarity between disks and background. Experiment 2 shows that the direction of these lightness effects is not influenced by the luminance of the size-contrast inducers. Experiment 3 shows that a similar lightness effect is also observed in modified Ebbinghaus size-contrast displays. Experiment 4 tested the presence of the size-contrast illusion in the stimuli used in experiments 2 and 3.     

Idiolects and Language

The present paper is intended to analyse from a theoretical point of view the relationships between natural language and idiolects in the context of communication by means of the Davidson–Dummett controversy on the nature of language. I will explore from a pragmatic point of view the reliability of an alternative position inspired by the recent literalism/contextualism debate in philosophy of language in order to overcome some limitations of Dummett’s and Davidson’s perspectives on language, idiolects and communication.     

Does terrain slope really dominate goal searching?

If you can locate a target by using one reliable source of information, why would you use an unreliable one? A similar question has been faced in a recent study on homing pigeons, in which, despite the presence of better predictors of the goal location, the slope of the floor in an arena dominated the searching process. This piece of evidence seems to contradict straightforward accounts of associative learning, according to which behavior should be controlled by the stimulus that best predicts the reward, and has fueled interest toward one question that, to date, has received scarce attention in the field of spatial cognition: how are vertical spaces represented? The purpose of this communication is to briefly review the studies on this issue, trying to determine whether slope is a special cue--driving behavior irrespective of other cues--or simply a very salient one.     

Eye gaze cannot be ignored (but neither can arrows)

Recent studies have tried to shed light on the automaticity of attentional shifts triggered by gaze and arrows with mixed results. In the present research, we aimed at testing a strong definition of resistance to suppression for orienting of attention elicited by these two cues. In five experiments, participants were informed with 100% certainty about the future location of a target they had to react to by presentation of either a direction word at the beginning of each trial or instructions at the beginning of each block. Gaze and arrows were presented before the target as uninformative distractors irrelevant for the task. The results showed similar patterns for gaze and arrows-namely, an interference effect when the distractors were incongruent with the upcoming target location. This suggests that the orienting of attention mediated by gaze and arrows can be considered as strongly automatic.     

Exploring classical conditioning for strengthening the links between semantic and lexical representations in pure anomia: Preliminary findings from a single case study

The same language symptom might arise at different functional loci in people with aphasia. Therefore, it is plausible that different therapeutic interventions should be adopted to approach the same difficulties in different patients. Although this point of view is still widely accepted, recently the focus has shifted from the functional locus of a rehabilitative intervention to the mechanisms of action underlying the relearning process. We maintain that both aspects should be taken into account when programming a rehabilitative intervention; furthermore, investigating relearning mechanisms might shed new light on the functional architecture of the disrupted processes. Here, we investigated, in a single case study, whether classical conditioning was a suitable relearning paradigm for targeting word‐finding difficulties in pure anomia, that is in a patient with an impairment in accessing intact output lexical representations from a spared semantic system. Using a word‐repetition task on picture presentation, we contrasted a condition in which the stimulus onset asynchrony between word and picture stimuli was well suited to produce classical conditioning with a condition in which repetition training could not benefit from this learning mechanism. Only classical conditioning training exerted a significant, long‐lasting effect on our patient's naming skill. Tentative implications of our results for the functional architecture of single‐word processing are discussed.     

Behavioral effects of testosterone in relation to social rank in the male rabbit

The role of gonadal androgens in favoring the adaptation to environmental pressure, including social organization, is well known. In the rabbit, testosterone administration increases marking behavior, and its level can be affected by agonistic interaction. In this experiment, we studied the effect of subcutaneous administration of testosterone propionate (TP) (3 mg/d for 6 days) in male rabbits belonging to the same social group (6 groups of 4 animals). In 2 additional groups (4 animals each), males were injected with almond oil. The animals were observed for 6 days in seminatural conditions, then treated with TP (or oil) and observed for another 6 days. The dominant/subordinate frequency ratio of behavioral patterns was used to rank the animals. The testosterone plasma concentration was correlated with agonistic behavior after the first period of social interaction. A significant increase of marking, digging, and defensive activity was observed after TP administration in all animals independent of rank, whereas this increase was not present in animals treated with oil. Agonistic and interactive behaviors increased significantly after TP treatment only in the first‐ranking animals. This indicates the influence of social rank in the modification of behaviors involving interactions among subjects Aggr. Behav. 29:269–278, 2003. © 2003 Wiley‐Liss, Inc.     

Virtual reality technology in neuropsychological testing: A systematic review

Neuropsychological testing aims to measure individuals' cognitive abilities (e.g. memory, attention), analysing their performance on specific behavioural tasks. Most neuropsychological tests are administered in the so-called ‘paper-and-pencil’ modality or via computerised protocols. The adequacy of these procedures has been recently questioned, with more specific concerns about their ecological validity, i.e. the relation between test scores observed in the laboratory setting and the actual everyday cognitive functioning. In developing more ecological tasks, researchers started to implement virtual reality (VR) technology as an administration technique focused on exposing individuals to simulated but realistic stimuli and environments, maintaining at the same time a controlled laboratory setting and collecting advanced measures of cognitive functioning. This systematic review aims to present how VR procedures for neuropsychological testing have been implemented in the last years. We initially explain the rationale for supporting VR as an advanced assessment tool, but we also discuss the challenges and risks that can limit the widespread implementation of this technology. Then, we systematised the large body of studies adopting VR for neuropsychological testing, describing the VR tools' distribution amongst different cognitive functions through a PRISMA-guided systematic review. The systematic review highlighted that only very few instruments are ready for clinical use, reporting psychometric proprieties (e.g. validity) and providing normative data. Most of the tools still need to be standardised on large cohorts of participants, having published only limited data on small samples up to now. Finally, we discussed the possible future directions of the VR neuropsychological test development linked to technological advances.