Brains that are out of tune but in time

It is estimated that about 4% of the general population may have amusia (or tone deafness). Congenital amusia is a lifelong disability for processing music despite normal intellectual, memory, and language skills. Here we present evidence that the disorder stems from a deficit in fine-grained pitch perception. Amusic and control adults were presented with monotonic and isochronous sequences of five tones (i.e., constant pitch and intertone interval). They were required to detect when the fourth tone was displaced in pitch or time. All amusic participants were impaired in detecting the pitch changes, and showed no sign of improvement with practice. In contrast, they detected time changes as well as control adults and exhibited similar improvements with practice. Thus, the degraded pitch perception seen in the amusic individuals cannot be ascribed to nonspecific problems with the task or to poor hearing in general. Rather, the data point to the presence of a congenital neural anomaly that selectively impairs pitch processing.     

Mass perturbation of a body segment: 2. Effects on interlimb coordination

The shifts in relative phase that are observed when rhythmically coordinated limbs are submitted to asymmetric mass perturbations have typically been attributed to the induced eigenfrequency difference (delta omega) between limbs. Modeling the moving limbs as forced linear oscillators, however, reveals that asymmetric mass perturbations may induce a difference not only in eigenfrequency (i.e., delta omega not equal 0) but also in the covarying low-frequency control gains (i.e., delta k not equal 0). Because the inverse of the low-frequency control gain (k) reflects the level of muscular torque (input) required for a particular displacement from equilibrium (output), asymmetric mass perturbations may result in an imbalance in the muscular torques required for task performance (related to delta k not equal 0). Thus, it is possible that the effects attributed to delta omega were in fact mediated by delta k. In 2 experiments, the authors manipulated delta k and delta omega separately by applying mass perturbations to the lower legs of 9 participants. The relative phasing between the legs was not affected by delta k, but manipulation of delta omega (while delta k remained approximately 0) induced systematic relative phase shifts that were more pronounced for antiphase than for in-phase coordination. That indication that the coordination dynamics is indeed influenced by an imbalance in eigenfrequency is discussed vis-a-vis the question of how such a merely peripheral property may affect the underlying coordination process.     

Prevention opportunities in health care settings

Psychologists have an opportunity to offer their expertise at a time when health care settings are beginning to recognize the importance of behaviorally based interventions for improving health and health care. The authors review the changing patterns of health and illness that have led to an increased interest in the role of patient and provider behavior and discuss the many advantages of using health care settings as prevention sites. Examples of successful behaviorally based prevention programs are presented, along with the evidence supporting the cost-effectiveness of such programs. Challenges presented by working in health care settings are described. Throughout, the authors emphasize the multiple opportunities for psychologists' involvement across a wide variety of health care delivery sites.     

Influence of consonantal context on the pronunciation of vowels: a comparison of human readers and computational models

In two experiments, we found that college students' pronunciations of vowels in nonwords are influenced both by preceding and following consonants. The predominance of rimes in previous studies of reading does not appear to arise because readers are unable to pick up associations that cross the onset-rime boundary, but rather because English has relatively few such associations. Comparisons between people's vowel pronunciations and those produced by various computational models of reading showed that no model provided a good account of human performance on nonwords for which the vowel shows contextual conditioning. Possible directions for improved models are suggested.     

The interactive effect of leader-member exchange and communication frequency on performance ratings

The authors tested the hypothesis that communication frequency moderates the relationship between leader-member exchange (LMX) and job-performance ratings. In a study of 188 private sector workers, they found that LMX was more strongly related to job-performance ratings among individuals reporting frequent communication with the supervisor than among those reporting infrequent communication. At high levels of LMX, workers reporting frequent communication with the supervisor received more favorable job-performance ratings than did workers reporting infrequent communication. In contrast, at low levels of LMX, workers reporting frequent communication with the supervisor received less favorable job-performance ratings than workers reporting infrequent communication. The authors conducted a 2nd study of 153 public sector workers to provide a constructive replication and found similar results.     

Predictors of posttraumatic stress disorder and symptoms in adults: a meta-analysis

A review of 2,647 studies of posttraumatic stress disorder (PTSD) yielded 476 potential candidates for a meta-analysis of predictors of PTSD or of its symptoms. From these, 68 studies met criteria for inclusion in a meta-analysis of 7 predictors: (a) prior trauma, (b) prior psychological adjustment, (c) family history of psychopathology, (d) perceived life threat during the trauma, (e) posttrauma social support, (f) peritraumatic emotional responses, and (g) peritraumatic dissociation. All yielded significant effect sizes, with family history, prior trauma, and prior adjustment the smallest (weighted r = .17) and peritraumatic dissociation the largest (weighted r = .35). The results suggest that peritraumatic psychological processes, not prior characteristics, are the strongest predictors of PTSD.     

Examining the construct validity of the Eating Disorder Inventory

The construct validity of the Eating Disorder Inventory (EDI) was examined in 3 samples. An archival clinic sample (n = 318) of women completed the EDI, a structured interview, and the Millon Clinical Multiaxial Inventory-II (MCMI-II). Confirmatory factor analyses (CFAs) indicated that neither null nor 1-factor models of the EDI fit item-level or item-parcel data. The proposed 8-factor model did not fit at the item level but did fit item-parcel data. Reliability estimates of the 8 scales ranged from .82 to .93, and low-to-moderate interscale correlations among the eating and weight-related scales provided partial support for convergent validity. EDI personality scales showed moderate interscale correlations and were associated with MCMI-II scales. A final CFA of the EDI scales supported a 2-factor model (Eating and Weight, Personality) of the 8 EDI scales. Strong associations between depression and several EDI scale scores were found in a treatment study sample (n = 50). The archival clinic sample scored significantly higher on the 8 EDI scales than the nonpatient college comparison sample (n = 487).     

The adaptive user: an investigation into the cognitive and task constraints on the generation of new methods

When people use a computer application, they have the opportunity to adapt the methods or strategies that they deploy to better fit the demands of the task. In Experiment 1, we demonstrated that the generation of methods is limited by, but not entirely prevented by, the reduced opportunity that is associated with the iterative nature of typical computer-based tasks. In Experiment 2, we demonstrated that the cognitive demands associated with task-related problem solving delay, but do not prevent, the generation of more efficient device strategies. We argue that people are rather good at adapting device strategies to task demands and that previously reported arguments to the contrary are premature.     

Child‐directed teaching and social learning at 18 months of age: evidence from Yucatec Mayan and US infants

In several previous studies, 18‐month‐old infants who were directly addressed demonstrated more robust imitative behaviors than infants who simply observed another's actions, leading theorists to suggest that child‐directed interactions carried unique informational value. However, these data came exclusively from cultural communities where direct teaching is commonplace, raising the possibility that the findings reflect regularities in infants' social experiences rather than responses to innate or a priori learning mechanisms. The current studies consider infants' imitative learning from child‐directed teaching and observed interaction in two cultural communities, a Yucatec Mayan village where infants have been described as experiencing relatively limited direct instruction (Study 1) and a US city where infants are regularly directly engaged (Study 2). Eighteen‐month‐old infants from each community participated in a within‐subjects study design where they were directly taught to use novel objects on one day and observed actors using different objects on another day. Mayan infants showed relative increases in imitative behaviors on their second visit to the lab as compared to their first visit, but there was no effect of condition. US infants showed no difference in imitative behavior in the child‐directed vs. observed conditions; however, infants who were directly addressed on their first visit showed significantly higher overall imitation rates than infants who observed on their first visit. Together, these findings call into question the idea that child‐directed teaching holds automatic or universal informational value.