The consequences of failing to imitate

Infants were shown three modeled acts presented in sequence. Imitation of one, two, or three of the modeled acts or failure to imitate was then observed. Distress was assessed prior to and following modeling. Infants who failed to imitate at least one act displayed a high level of distress. As a control, the same infants on another day observed the random manipulation of the stimuli. Distress failed to occur when the infants failed to imitate the scattering procedure. These results are discussed in terms of the child's development of internal standards. That is, during the latter part of the second year of life, infants show considerable distress when they fail to imitate coherent modeled acts. Since distress did not occur when the model simply scattered the stimuli, we assumed that interruption of play was not an incentive for distress. Deferred imitation was noted for older but not the younger cohorts.     

Genetic and environmental origins of verbal and performance components of cognitive delay in 2-year-olds.

The authors investigated the etiology of several measures of cognitive delay. Verbal (V) and performance (P) abilities were assessed in over 3,000 pairs of 2-year-old twins. Group-differences heritability for general delay (the lowest 5% of the V and P composite) was 35%. However, V and P delays considered independently showed large differences in group heritability (77% for V vs. 40% for P). Specific delays with comorbid cases eliminated showed an even greater difference in group heritability (78% vs. 22%, respectively). The small sample comorbid for both V and P delay also yielded high group heritability for both V (77%) and P (93%) scores. Shared environmental factors also differed in magnitude for V (20%) and P (41%) delays. Because the genetic and environmental origins of V and P delays in infancy differ, they are better considered separately rather than combined into a composite measure of general cognitive delay.     

From field experiments to program implementation: Assessing the potential outcomes of an experimental intervention program for unemployed persons

Demonstrated a procedure suggested by Bloom (1984) to provide estimates for the effects of an intervention on its actual participants compared to global effects on study participants in the intervention group, whether or not they showed up. Analyses were based on data collected in a field experiment that tested a preventive intervention for unemployed persons (Caplan, Vinokur, Price & van Ryn, 1989). Effect size estimates were two to three times larger for the actual participant group than for the entire experimental group on employment outcomes (e.g., earnings) and mental health (anxiety and depression). Further analyses produced results showing that compared to participants, the nonparticipants achieved significantly higher levels of reemployment at posttests and did not differ significantly from participants on all other outcomes. The results suggest that persons who most needed the intervention and benefited from it were drawn into it through self-selection processes.     

The dorsal tegmental noradrenergic projection: an analysis of its role in maze learning.

The hypothesis that the noradrenergic projection from the locus coeruleus (LC) to the cerebral cortex and hippocampus is an important neural substrate for learning was evaluated. Maze performance was studied in rats receiving either electrolytic lesions of LC or 6-hydroxydopamine (6-OHDA) lesions of the dorsal tegmental noradrenergic projection. The LC lesions did not disrupt the acquisition of a running response for food reinforcement in an L-shaped runway, even though hippocampal-cortical norepinephrine (NE) was reduced to 29%. Greater telencephalic NE depletions (to 6% of control levels) produced by 6-OHDA also failed to disrupt the acquisition of this behavior or to impair the acquisition of a food-reinforced position habit in a T-maze. Neither locomotor activity nor habituation to a novel environment was affected by the 6-OHDA lesions. Rats with such lesions were, however, found to be significantly more distractible than were controls during the performance of a previously trained response. The hypothesis that telencephalic NE is of fundamental importance in learning was not supported. The data suggest that this system may participate in attentional mechanisms.     

Maximally correlated orthogonal composites and oblique factor analytic solutions

Kaiser presented a method for finding a set of derived orthogonal variables which correlate maximally with a set of original variables. A simpler, more complete derivation of Kaiser's result is given and compared to related types of transformations. The transformation derived here suggests a direct method for finding the orthogonal factor solution which is maximally similar to a given oblique solution.     

Relocating 65xx software timing routines

Price’s (1979) machine language timing subroutines are modified to make relocation easier by means of relative branching commands and use of screen holes for data storage.     

Software timing for 6500 series microcomputers

Two machine language programs are presented for use in behavioral research requiring timing of reaction latencies, stimulus presentations, or intertrial intervals. Sample programs in BASIC show how to load and use the subroutines, and suggestions are made for possible modifications to a variety of situations.     

Fringe consciousness in sequence learning: the influence of individual differences

We first describe how the concept of “fringe consciousness” ([Mangan, 1993a], [Mangan, 1993b], [Mangan, 2001] and [Mangan, 2003]) can characterise gradations of consciousness between the extremes of implicit and explicit learning. We then show that the NEO-PI-R personality measure of openness to feelings, chosen to reflect the ability to introspect on fringe feelings, influences both learning and awareness in the serial reaction time (SRT) task under conditions that have previously been associated with implicit learning ([Destrebecqz and Cleeremans, 2001] and [Destrebecqz and Cleeremans, 2003]). This provides empirical evidence for the proposed phenomenology and functional role of fringe consciousness in so-called implicit learning paradigms (Mangan, 1993b). Introducing an individual difference variable also helped to identify possible limitations of the exclusion task as a measure of conscious sequence knowledge. Further exploration of individual differences in fringe awareness may help to avoid polarity in the implicit learning debate, and to resolve apparent inconsistencies between previous SRT studies.