Holistic representation of unit fractions

The present study examined the processing of unit fractions and the extent to which it is affected by context. Using a numerical comparison task we found evidence for a holistic representation of unit fractions when the immediate context of the fractions was emphasized, that is when the stimuli set included in addition to the unit fractions also the numbers 0 and 1. The holistic representation was indicated by the semantic congruity effect for comparisons of pairs of fractions and by the distance effect in comparisons of a fraction and 0 and 1. Consistent with previous results (Bonato, Fabbri, Umilta, & Zorzi, 2007) there was no evidence for a holistic representation of unit fractions when the stimulus set included only fractions. These findings suggest that fraction processing is context-dependent. Finally, the present results are discussed in the context of processing other complex numbers beyond the first decade.     

A model of top-down gain control in the auditory system

To evaluate a model of top-down gain control in the auditory system, 6 participants were asked to identify 1-kHz pure tones differing only in intensity. There were three 20-session conditions: (1) four soft tones (25, 30, 35, and 40 dB SPL) in the set; (2) those four soft tones plus a 50-dB SPL tone; and (3) the four soft tones plus an 80-dB SPL tone. The results were well described by a top-down, nonlinear gain-control system in which the amplifier’s gain depended on the highest intensity in the stimulus set. Individual participants’ identification judgments were generally compatible with an equal-variance signal-detection model in which the mean locations of the distribution of effects along the decision axis were determined by the operation of this nonlinear amplification system.     

Asymmetry between encoding and retrieval processes: Evidence from divided attention and a calibration analysis

Two experiments provide further information on the effects of divided attention (DA) on encoding and retrieval processes. The first experiment examined the effects of decision and motor difficulty of a concurrent reaction time task. A calibration analysis was used in the second experiment to test the hypothesis that shifting attentional emphasis away from encoding to the secondary task reduces the level of processing the to-be-remembered items receive. Overall, the results confirm and extend the conclusions of Craik, Govoni, Naveh-Benjamin, and Anderson (1996) and Naveh-Benjamin, Craik, Guez, and Dori (1998), by pointing to clear differences between encoding and retrieval processes: Encoding is affected by simultaneous task demands, especially those associated with "central" resources involved in conscious decision making, whereas retrieval is obligatory in that it is largely immune to the effects of simultaneous demands. The results of the calibration analysis suggest that one reason for the poorer memory performance as a result of DA at encoding is a qualitative shift to less deep, elaborative strategies.     

Memory for targets in a multilevel simulated environment: Evidence for vertical asymmetry in spatial memory

In two experiments, adult participants explored a symmetrical three-tiered computer-simulated building that contained six distinctive objects, two on each floor. Following exploration, the objects were removed, and the participants were asked to make direction judgments from each floor, indicating the former positions of the objects on that floor and on higher and lower floors. Relative tilt error scores indicated a bias, in that targets that were higher than the test location were judged as consistently lower than their actual positions and targets that were lower than the test location were judged as consistently higher than their actual positions. Absolute tilt errors revealed an asymmetry, with more accurate and less variable tilt errors for judgments directed to lower floors than for judgments directed to higher floors. Experiment 3 ruled out an account of the findings that does not relate them to spatial memory. The results suggest that the superiority of downward over upward spatial judgments, previously reported in two-dimensional visual-spatial tasks, extends to navigational spatial memory.     

Autobiographical memory in middle childhood: recollections of the recent and distant past

To address the question of whether memories from early childhood survive into later childhood, participants visited the laboratory at age 3 and again at 7, 8, or 9. At age 3, each talked with a parent about six events; at the later age each child talked with a researcher about four of these distant events as well as two more recent events. School-aged children recalled fewer than half of the distant events introduced. Further, the proportion of distant events recalled was negatively correlated with age. Those distant events that were recalled, however, were recounted in an accurate, detailed manner. Importantly, reports of distant events did not reflect the full extent of children's narrative ability. Reports of recent events were more coherent and included twice the detail. Implications for existing interpretations of autobiographical memory and childhood amnesia are discussed, and the need for further research employing innovative methods is emphasised.     

Women with low activity are at increased risk for depression

This study assessed if there are sex differences in the relationship between amount of physical activity and depression in primary care outpatients. Participants (N= 111), referred by their family physicians, wore a heart-rate monitor for 24 hr. The two-lead monitor collected the number of beats per minute and minute-averaged horizontal movement data, e.g., from walking or moving about. All participants underwent structured clinical interviewing using the Structured Clinical Interview for DSM-IV and completed the Beck Depression Inventory-II and the Symptom Checklist-90-Revised. For the total sample, patients with low activity were more likely to be depressed (p<.006). Adults under the age of 45 (n=85) with low activity were 7.4 times more likely to be depressed than young adults who showed normal activity. However, in adults 45 or older, there was no relationship between activity and depression. In a subsample of women under the age of 55 (n=70), 91% of the low activity group and 39% of the normal activity group were diagnosed with depression (p<.003). Women in the low activity group were 15.7 times more likely to be depressed than women in the normal activity group. In contrast, there was no relationship between activity and depression in men. Additional research is needed to assess whether low activity is a potent predictor of depression in women.     

Gender recognition from point-light walkers

Point-light displays of human gait provide information sufficient to recognize the gender of a walker and are taken as evidence of the exquisite tuning of the visual system to biological motion. The authors revisit this topic with the goals of quantifying human efficiency at gender recognition. To achieve this, the authors first derive an ideal observer for gender recognition on the basis of center of moment (J. E. Cutting, D. R. Proffitt, & L. T. Kozlowski, 1978) and, with the use of anthropometric data from various populations, show optimal recognition of approximately 79% correct. Next, they perform a meta-analysis of 21 experiments examining gender recognition, obtaining accuracies of 66% correct for a side view and 71% for other views. Finally, results of the meta-analysis and the ideal observer are combined to obtain estimates of human efficiency at gender recognition of 26% for the side view and 47% for other views.     

Memory and goal setting: the response of older and younger adults to positive and objective feedback

Earlier research suggested that goal setting for memory does not have the same advantages for older adults as for younger adults. Using ideal goal-setting conditions with individualized goals, the authors compared goals plus positive feedback, goals plus objective feedback, and control. Performance increased over trials and was higher for both goal conditions than for control. The positive feedback condition showed the highest goal commitment and motivation. Older adults showed strong performance gains and more motivation and goal commitment than the young. The results showed that older adults can benefit from goal setting under optimal learning and feedback conditions.     

The role of embodied intention in early lexical acquisition

We examine the influence of inferring interlocutors' referential intentions from their body movements at the early stage of lexical acquisition. By testing human participants and comparing their performances in different learning conditions, we find that those embodied intentions facilitate both word discovery and word-meaning association. In light of empirical findings, the main part of this article presents a computational model that can identify the sound patterns of individual words from continuous speech, using nonlinguistic contextual information, and employ body movements as deictic references to discover word-meaning associations. To our knowledge, this work is the first model of word learning that not only learns lexical items from raw multisensory signals to closely resemble infant language development from natural environments, but also explores the computational role of social cognitive skills in lexical acquisition.     

Risk and Resiliency Factors Influencing Suicidality Among Urban African American and Latino Youth

For decades, suicide rates among minority African American and Latino young people have been stable and, when compared with Whites, relatively low. This is no longer the case, underscoring the need for documenting and understanding the problem of suicidality in this population. We report on the prevalence and predictors of suicidality among 879 urban adolescents in the Reach for Health study. All youth resided in economically disadvantaged neighborhoods; 69% were African American, 16% Latino, and 15% reported mixed or other ethnicity. In the past year, 15% had seriously considered suicide; 13% had made a suicide plan, 11% had attempted suicide at least once, and 4% reported multiple attempts. Risk factors significantly related to suicidal ideation are being female, having basic needs unmet, engaging in same-gender sex, and depression. Resiliency factors include family closeness and, marginally, religiosity. Risk factors related to reports of suicide attempts are being female, being Hispanic, and depression; family closeness is strong resiliency factor. Family composition, ethnic identity, coping style, peer support, and school attachment are not significant correlates of suicidal ideation or attempts.