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 .     

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.     

An initial investigation of baseline respiratory sinus arrhythmia as a moderator of treatment outcome for young children born premature with externalizing behavior problems

The aim of the current study was to examine the moderating effect of baseline respiratory sinus arrhythmia (RSA) on Parent-Child Interaction Therapy (PCIT), a behavioral parent-training intervention, for young children born premature. In this pilot randomized controlled trial, 28 young children (mean age of 37.79 months), who were born <37 weeks gestation and presented with elevated externalizing behavior problems, were randomly assigned to an immediate treatment or waitlist control group. RSA, which provides an approximate marker of individual differences in cardiac vagal tone, was measured during a baseline period. Past research has generally shown that higher levels of baseline RSA correlate with various positive psychological states (e.g., empathy, sustained attention), whereas lower levels of baseline RSA correlate with less optimal psychological states (e.g., higher externalizing behavior problems). Results indicated that baseline RSA significantly interacted with treatment condition in predicting changes in child disruptive behavior. Specifically, low levels of baseline RSA were associated with greater improvements in child disruptive behavior following PCIT. While acknowledging the caveats of measuring and interpreting RSA and the need to include a sympathetic-linked cardiac measure in future research, these findings provide preliminary evidence that children with lower capacity for emotion regulation receive even greater treatment gains. Future research should also examine the moderating effect of RSA in larger samples and explore the potential mediating role of RSA on behavioral parenting interventions.