Effects of joint immobilization on standing balance

We investigated the effect of joint immobilization on the postural sway during quiet standing. We hypothesized that the center of pressure (COP), rambling, and trembling trajectories would be affected by joint immobilization. Ten young adults stood on a force plate during 60 s without and with immobilized joints (only knees constrained, CK; knees and hips, CH; and knees, hips, and trunk, CT), with their eyes open (OE) or closed (CE). The root mean square deviation (RMS, the standard deviation from the mean) and mean speed of COP, rambling, and trembling trajectories in the anterior–posterior and medial–lateral directions were analyzed. Similar effects of vision were observed for both directions: larger amplitudes for all variables were observed in the CE condition. In the anterior–posterior direction, postural sway increased only when the knees, hips, and trunk were immobilized. For the medial–lateral direction, the RMS and the mean speed of the COP, rambling, and trembling displacements decreased after immobilization of knees and hips and knees, hips, and trunk. These findings indicate that the single inverted pendulum model is unable to completely explain the processes involved in the control of the quiet upright stance in the anterior–posterior and medial–lateral directions.     

How Can Experts See the Invisible? Reply to Bilalić and Gobet

Experts in all fields are able to see what is invisible to others. Experts are also able to see what is visible to all—and this is explored by Bilalić and Gobet. We question the method of normalizing all subjects in an experimental condition, and asking experts to behave as if they were novices. We claim that method leads Bilalić and Gobet to a nonsequitur .     

Does the eye know calculus? The threshold of representation in classical and connectionist models

The notion of representation lies at the crossroads of questions about the nature of belief and knowledge, meaning, and intentionality. But there is some hope that it might be simpler than all those. If we could understand it clearly, it might then help to explicate those more difficult notions. In this paper, my central aim is to find a principled criterion, along lines that make biological sense, for deciding just when it becomes theoretically plausible to ascribe to some process or state a representational role. I shall be especially concerned with some differences, in this regard, between classical and connectionist models. The relation between ‘standard’ artificial intelligence and connectionism turns out to illustrate a ‘first in, last out’ principle: What we most easily understand (and so can program) is what we have most recently invented; tasks we ourselves perform best, by contrast, are a lot harder to understand. Classical AI has modelled the former; connectionism tries to tackle the latter. I end with some speculations about the possible implications of these considerations for our understanding of understanding.     

Effects of repeated acquisitions and extinctions on response rate and pattern

The procedure developed by R. A. Rescorla (2002) was used to study the effects of repeated acquisitions and extinctions of head entry responses into a food cup by rats. In each of 4 20-session phases, food was delivered at the end of particular 30-s auditory and visual stimuli, but not at the end of different 30-s auditory and visual stimuli. Based on response rates to individual stimuli and compound stimuli, the increase in response rate in acquisition occurred more rapidly than the decrease in extinction. Acquisition, but not extinction, occurred faster after successive transitions between acquisition and extinction. Temporal gradients of responding developed during acquisition and remained during extinction. Conclusions based on mean response rate, temporal gradients, and transfer tests were consistent.     

Evaluating feature-category relations using semantic fluency tasks

The issue of the relationship between semantic features and semantic categories has been raised by Warrington and colleagues, who claimed that sensory and functional-associative features are differentially important in determining the meaning of living and nonliving things (Warrington & McCarthy, 1983, 1987; Warrington & Shallice, 1984). In the present study, the effectiveness of semantic memory search for living and nonliving things with sensory and functional-associative search cues was evaluated through eight different adaptations of the semantic fluency task. More living thing responses and clusters were generated from sensory than from functional-associative search cues, while the reverse pattern holds for nonliving things responses and clusters. The results thus provide consistent empirical support for the assumption that sensory properties are fundamental in the representation of living things, while functional-associative properties are fundamental in the semantic representation of nonliving things.     

Structural environmental enrichment and the way it is offered influence cognitive judgement bias and anxiety-like behaviours in zebrafish

Animal Cognition - Environmental enrichment in zebrafish generally reduces anxiety-related behaviours, improves learning in maze trials and increases health and biological fitness. However, certain...