Is the number of trials a primary determinant of conditioned responding?

Acquisition of conditioned responding is thought to be determined by the number of pairings of a conditioned stimulus (CS) and an unconditioned stimulus (US). However, it is possible that acquisition is primarily determined not by the number of trials but rather by quantities that often correlate with the number of trials, such as cumulative intertrial interval (ITI) and the number of sessions. Four experiments examined whether the number of trials has an effect on acquisition of conditioned responding, once cumulative ITI and number of sessions are equated. Results of the experiments with rats and mice favor the hypothesis that over an eightfold range, variation in number of CS-US pairings has little effect. It is suggested that learning curves might more accurately be plotted across cumulative ITI or number of sessions, and not across number of trials. Results pose a challenge to trial-centered accounts of conditioning, as demonstrated by simulations of the Rescorla-Wagner model, a simplified version of Wagner's standard operating procedure model (SOP), and Stout & Miller's sometimes competing retrieval model (SOCR). A time-centered account, rate estimation theory (RET), predicts the main finding but has trouble with other aspects of the learning process more easily accommodated by trial-centered models.     

Attachment, depression, and fear of death in older adults: The roles of neediness and perceived availability of social support

This study investigated individual differences in depression and fear of death in older adulthood in the context of attachment theory. The roles of neediness and perceived availability of social support were examined. Participants were 113 Israeli older adults (aged 69–85) who were all in good health and functioning well. Social support was found to moderate the association between a low positive other-dimension (PO) of attachment and fear of death. Neediness mediated the relationships between a low positive self-dimension (PS) of attachment and depression. Findings are discussed within the framework of Bowlby’s distinction between attachment and dependency.     

Measuring children's regulation of emotion-expressive behavior

Emotion regulation has become a pivotal concept in developmental and clinical research. However, the measurement of regulatory processes has proved extremely difficult, particularly in the context of within-subject designs. Here, we describe a formal conceptualization and a new experimental procedure, the Balloons Game, to measure a regulatory component of emotion-expressive behavior. We present the internal consistency and stability of the indices derived from the Balloons Game in a sample of 121 kindergarten children. External validation against measures that have been associated with emotion regulation processes is also provided. The findings suggest that the Balloons Game provides a reliable tool for the study of regulation of emotion expression in young children.     

Rate it again: Using the wisdom of many to improve performance evaluations

Much research shows that judgmental estimation could be improved by combining estimates from independent judges as well as within judges. These results have been obtained mostly with judgments about matters of fact, that is, for which there are objective truth criteria. In the present research, we extend these findings to performance evaluations. In a controlled field study, expert judges provided evaluations of a large number of essays written by college applicants taking college entrance tests. The judges were asked to evaluate each essay twice—on two occasions, a week apart. This design allowed us to assess the benefits of two methods of combining evaluations: within rater and across raters. Accuracy gains were obtained with both methods. Although the within‐rater combinations yielded fewer gains than the across‐rater ones, they were still appreciable in comparison with the across rater ones. Our findings extend the class of judgments to which the “wisdom of many” could be applied. These findings are potentially applicable to performance evaluations in social, educational, and employment settings.     

Imaging brain plasticity during motor skill learning

The search for the neural substrates mediating the incremental acquisition of skilled motor behaviors has been the focus of a large body of animal and human studies in the past decade. Much less is known, however, with regard to the dynamic neural changes that occur in the motor system during the different phases of learning. In this paper, we review recent findings, mainly from our own work using fMRI, which suggest that: (i) the learning of sequential finger movements produces a slowly evolving reorganization within primary motor cortex (M1) over the course of weeks and (ii) this change in M1 follows more dynamic, rapid changes in the cerebellum, striatum, and other motor-related cortical areas over the course of days. We also briefly review neurophysiological and psychophysical evidence for the consolidation of motor skills, and we propose a working hypothesis of its underlying neural substrate in motor sequence learning.     

Influence of strategy on muscle activity during impact movements

Participants (N = 10) made flexions or extensions about the elbow. Movements either were pointing (i.e., self-terminated) or terminated by impact on a barrier. The author examined how the trajectory and the electromyographic (EMG) patterns varied according to the distance moved, the instruction provided concerning speed, or the type of termination. Variations in kinematics induced by changes in the target distance or the instruction regarding speed were the same for impact and pointing movements. In comparison with a pointing movement of similar distance and speed instruction, an impact movement (a) accelerated longer and reached a higher velocity, (b) had a longer agonist EMG burst, and (c) had a low level of contraction that started slightly after the agonist burst and continued throughout the movement but had little or no antagonist burst. Because the different types of movements required different forces from the muscles, there were systematic, task-specific differences in EMG patterns that reflected task-specific differences in central control. The results of this experiment demonstrate that impact movements share some of the rules used in the control of other tasks, such as pointing and reversing movements. The sharing is not imposed by mechanical or physiological constraints but, rather, represents the imposition of internal constraints.