Mechanisms of predictive and diagnostic causal induction

In predictive causal inference, people reason from causes to effects, whereas in diagnostic inference, they reason from effects to causes. Independently of the causal structure of the events, the temporal structure of the information provided to a reasoner may vary (e.g., multiple events followed by a single event vs. a single event followed by multiple events). The authors report 5 experiments in which causal structure and temporal information were varied independently. Inferences were influenced by temporal structure but not by causal structure. The results are relevant to the evaluation of 2 current accounts of causal induction, the Rescorla-Wagner (R. A. Rescorla & A. R. Wagner, 1972) and causal model theories (M. R. Waldmann & K. J. Holyoak, 1992).     

Matching and naming objects by shape or function: age and context effects in preschool children

Three experiments tested preschoolers' use of abstract principles to classify and label objects by shape or function. Three- and 4-year-olds were instructed to match objects by shape or function. Four-year-olds readily adopted either rule, but 3-year-olds followed only the shape rule. Without a rule, 4-year-olds tended to match by shape unless object function was shown during matching (Experiment 2). Three-year-olds' ability to use a function rule was tested in several conditions (re-presenting functions; reminders to "use the rule"; repeating rule on every trial). None induced consistent function matching (Experiment 3). Supplemental memory and verbal tasks showed that 3-year-olds have trouble using function as an abstract basis of comparison. Naming data, however, show that preschoolers are learning that object labels are based on function. The results show preschoolers' growing flexibility in adopting abstract generalization rules and growing knowledge of conventions for extending words.     

The role of priming in conjunctive visual search

To assess the role of priming in conjunctive visual search tasks, we systematically varied the consistency of the target and distractor identity between different conditions. Search was fastest in the standard conjunctive search paradigm where identities remained constant. Search was slowest when potential target identity varied predictably for each successive trial (the 'switch' condition). The role of priming was also demonstrated on a trial-by-trial basis in a 'streak' condition where target and distractor identity was unpredictable yet was consistent within streaks. When the target to be found was the same for a few trials in a row, search performance became similar to that when the potential target was the same on all trials. A similar pattern was found for the target absent trials, suggesting that priming is based on the whole search array rather than just the target in each case. Further analysis indicated that the effects of priming are sufficiently strong to account for the advantage seen for the conjunctive search task. We conclude that the role of priming in visual search is underestimated in current theories of visual search and that differences in search times often attributed to top-down guidance may instead reflect the benefits of priming.     

Building phonotactic knowledge in bilinguals: role of early exposure

Timing and amount of exposure to a 2nd language in the acquisition of phonotactic restrictions was examined in 4 experiments. In Experiments 1 and 2, 10-month-old monolingual and bilingual Catalan-Spanish infants were presented with nonwords that were phonotactically legal or illegal in Catalan and phonotactically illegal in Spanish. Differences between the 4 groups of infants were obtained as a function of language dominance. In Experiments 3 and 4, adult Spanish-Catalan bilinguals were compared with the same materials. Catalan-dominant bilinguals were more accurate than Spanish-dominant bilinguals in their perception of legal sequences; however, they were not more accurate with illegal sequences. The findings suggest a complex correlation between the pattern of preference and the amount and timing of exposure.     

The association between homelessness and suicidal ideation and behaviors: results of a cross-sectional survey

This study was carried out with three goals: (1) to determine the prevalence of suicidal ideation and suicide attempts among the homeless; (2) to determine what aspects of homelessness predict suicidality, and (3) to determine which aspects remain predictive after controlling for key covariates, such as mental illness. A sample of 330 homeless adults were interviewed. Sixty-one percent of the study sample reported suicidal ideation and 34% had attempted suicide. Fifty-six percent of the men and 78% of the women reported prior suicidal ideation, while 28 percent of the men and 57% of the women had attempted suicide. Childhood homelessness of at least 1 week without family members and periods of homelessness longer than 6 months were found to be associated with suicidal ideation. Psychiatric diagnoses were also associated with suicidality in this sample.     

Can Temperament Identify Affectively Ill Patients Who Engage in Lethal or Near‐Lethal Suicidal Behavior? A 14‐Year Prospective Study

Among affectively ill patients followed naturalistically for up to 14 years, 36 committed suicide, 120 attempted suicide, and 373 had no recorded suicide attempt. Comparing these three groups on clinical and intake personality revealed that suicide completed within 12 months was predicted by clinical but not personality variables, and suicide beyond 12 months was predicted by newly derived temperament factors, not clinical variables. Attempters and completers shared core characteristics: previous attempts, impulsivity, substance abuse, and psychic turmoil within a cycling/mixed bipolar disorder. Such temperament attributes as impulsivity and assertiveness were the best prospective predictors of completed suicides beyond 12 months with a sensitivity level of 74% and specificity level of 82%.     

A pragmatic guideline for evaluation of social intervention

Considering the many theoretical and methodological viewpoints in the field of evaluation, a guideline was established to facilitate the evaluation of social intervention programs. For this purpose, the goals of the evaluation were taken into account: (a) planning interventions, (b) learning and continuous improvement of interventions, (c) programming policies, and (d) transformation of society. These goals will determine the perspective of the analysis selected (focusing on the evaluand or the context) and the strategies for change employed (focusing on processes or results). The elements that, according to Shadish, Cook, and Levinton (1991), constitute the theory of evaluation (evaluand, value, building of knowledge, and uses) have also been considered. The analysis of all these components led to the elaboration of a guideline to orient the practice of evaluation from a pragmatic perspective, in accordance with the demands and needs of a certain social context.     

Does quantity generate quality? Testing the fundamental principle of brainstorming

The purpose of this work is to test the chief principle of brainstorming, formulated as "quantity generates quality." The study is included within a broad program whose goal is to detect the strong and weak points of creative techniques. In a sample of 69 groups, containing between 3 and 8 members, the concurrence of two commonly accepted criteria was established as a quality rule: originality and utility or value. The results fully support the quantity-quality relation (r = .893): the more ideas produced to solve a problem, the better quality of the ideas. The importance of this finding, which supports Osborn's theory, is discussed, and the use of brainstorming is recommended to solve the many open problems faced by our society.     

Understanding academic attitudes and achievement in mexican-origin youths: ethnic identity, other-group orientation, and fatalism

This study tested the relationships among ethnic identity, other-group orientation, fatalism, and 2 dependent variables: attitude toward education and school, and grade point average (GPA). Mexican-origin adolescents (N = 222) completed the Multigroup Ethnic Identity Measure (J. S. Phinney, 1992), the fatalism scale of the Multiphasic Assessment of Cultural Constructs-Short Form (I. Cuellar, B. Arnold, & G. Gonzalez, 1995), and the attitude scale of the Learning and Study Strategies Inventory-High School (C. E. Weinstein & D. R. Palmer, 1990a). Other-group orientation was positively related to attitude and GPA, and a negative relationship between fatalism and attitude was demonstrated. No relationship emerged between ethnic identity and the dependent variables.     

Non-invasive estimation of local field potentials for neuroprosthesis control

Recent experiments have shown the possibility of using the brain electrical activity to directly control the movement of robots or prosthetic devices in real time. Such neuroprostheses can be invasive or non-invasive, depending on how the brain signals are recorded. In principle, invasive approaches will provide a more natural and flexible control of neuroprostheses, but their use in humans is debatable given the inherent medical risks. Non-invasive approaches mainly use scalp electroencephalogram (EEG) signals and their main disadvantage is that these signals represent the noisy spatiotemporal overlapping of activity arising from very diverse brain regions, i.e., a single scalp electrode picks up and mixes the temporal activity of myriads of neurons at very different brain areas. In order to combine the benefits of both approaches, we propose to rely on the non-invasive estimation of local field potentials (LFP) in the whole human brain from the scalp measured EEG data using a recently developed inverse solution (ELECTRA) to the EEG inverse problem. The goal of a linear inverse procedure is to de-convolve or un-mix the scalp signals attributing to each brain area its own temporal activity. To illustrate the advantage of this approach we compare, using an identical set of spectral features, classification of rapid voluntary finger self-tapping with left and right hands based on scalp EEG and non-invasively estimated LFP on two subjects using a different number of electrodes.