Thinking about conditionals: A study of individual differences

Recent studies have shown the existence of two qualitatively distinct groups of people based on how they judge the probability of a conditional statement. The present study was designed to test whether these differences are rooted in distinctive means of processing conditional statements and whether they are linked to differences in general intelligence. In the study, each of 120 participants completed three separate cognitive tasks involving the processing of abstract conditional statements--the probability-of-conditionals task, the conditional truth table task, and the conditional inference task--in addition to completing a test of general intelligence (AH4). The results showed a number of predicted effects: People responding with conditional (rather than conjunctive) probabilities on the first task were higher in cognitive ability, showed reasoning patterns more consistent with a suppositional treatment of the conditional, and showed a strongly "defective" truth table pattern. The results include several novel findings and post challenges to contemporary psychological theories of conditionals.     

Token mediated tool exchange between tufted capuchin monkeys (<Emphasis Type="Italic">Cebus apella</Emphasis>)

Three experiments were conducted to test whether a pair of tufted capuchin monkeys (Cebus apella) could generalize their ability to exchange tokens and tool objects with a human experimenter to similar exchanges with a conspecific partner. Monkeys were tested in side-by-side enclosures, one enclosure containing a tool-use apparatus and one or more token(s), and the other enclosure containing one or more tool object(s). The monkeys willingly transferred tokens and tools to a conspecific with little practice. Following a small amount of training, we also found that the monkeys would select situation-appropriate tokens to exchange for specific tools, but did not select appropriate tool objects in response to another monkey’s token transfers. Implications regarding role reversal are discussed.     

Delay of gratification and delay maintenance by rhesus macaques (Macaca mulatta)

The authors tested the self-control of rhesus macaques by assessing if they could refrain from reaching into a food container to maximize the accumulation of sequentially delivered food items (a delay-maintenance task). Three different versions of the task varied the quantity and quality of available food items. In the first 2 versions, food items accumulated across the length of the trial until a monkey consumed the items. In the 3rd task, a single less-preferred food item preceded a single more-preferred food item. Some monkeys delayed gratification even with relatively long delays between deliveries of items. However, the data suggested that self-control, in the majority of tested individuals, was not significantly different across different task versions and that self-control by macaques was not as prevalent in these tasks as it is in chimpanzees and human children.     

Event memory and misinformation effects in a gorilla (<Emphasis Type="Italic">Gorilla gorilla gorilla</Emphasis>)

Event memory and misinformation effects were examined in an adult male gorilla ( Gorilla gorilla gorilla). The gorilla witnessed a series of unique events, involving a familiar person engaging in a novel behavior (experiment 1), a novel person engaging in a novel behavior (experiment 2), or the presentation of a novel object (experiment 3). Following a 5- to 10-min retention interval, a tester gave the gorilla three photographs mounted on wooden cards: a photograph depicting the correct person or object and two distractor photographs drawn from the same class. The gorilla responded by returning a photograph. If correct, he was reinforced with food. Across three experiments, the gorilla performed significantly above chance at recognizing the target photograph. In experiment 4, the gorilla showed at-chance performance when the event was followed by misinformation (a class-consistent, but incorrect photograph), but significantly above-chance performance when no misinformation occurred (either correct photograph or no photograph). Although the familiarity can account for these data, they are also consistent with an episodic-memory interpretation.     

Understanding print: early reading development and the contributions of home literacy experiences

This study explored the development of children's early understanding of visual and orthographic aspects of print and how this is related to early reading acquisition. A total of 474 children, ages 48 to 83 months, completed standardized measures of phonological awareness and early reading skills. They also completed experimental tasks that tapped their understanding of what constitutes "readable" print. The parents of participants completed a questionnaire regarding their children's home literacy experiences. The data showed systematic development in children's understanding of print conventions and English orthography and spelling. Regression analyses indicated that print knowledge was related to early reading skill, even after accounting for variance due to age and phonological awareness. Furthermore, parents' ratings of the extent of their children's involvement in activities that led to practice in reading and writing most consistently predicted the development of emerging literacy skills, including understanding of the conventions of the English writing system. Little relation between print knowledge and the frequency of storybook reading by adults was observed.     

A comparison of the other-directed stigmatization produced by legal and illegal forms of affirmative action

Recent studies have begun to show that the stigma of incompetence sometimes directed toward the beneficiaries of affirmative action may be significantly reduced as the preferences granted to women and minorities become more moderate. The author examined whether the stigmatization of African Americans would differ under hiring policies that represented legal and illegal levels of racial preference according to federal regulations. Participants were 178 students and 161 corporate employees who rated fictitious Black and White target employees working under (a) an illegal policy of selection of unequal candidates, (b) a legal policy of selection of comparable candidates, or (c) equal opportunity. Participants rated Black targets' achievement-related traits lower than White targets only under the illegal policy. Under the legal policy, no such stigmatization was observed. Additional dependent measures and theoretical implications were explored.     

The prevalence of suicidal phenomena in adolescents: a systematic review of population-based studies

The results of a systematic review of the international literature on the prevalence of suicidal phenomena in adolescents, including the influence of survey method, gender, and ethnicity are reported. The literature was searched using six electronic databases to identify all population-based studies of self-reported suicidal phenomena; 128 studies were included, comprising 513,188 adolescents. The mean proportion of adolescents reporting they had attempted suicide at some point in their lives was 9.7% (95% CI, 8.5-10.9), and 29.9% (95% CI, 26.1-33.8) of adolescents said they had thought about suicide at some point. Females were significantly more likely than males to report most suicidal phenomena. A lower prevalence of some suicidal phenomena was found for Asian populations. The prevalence of suicidal phenomena varied depending on the terminology used and tended to be higher in studies employing anonymous questionnaires than in studies employing non-anonymous methods (questionnaires or interviews), although most of these differences were not statistically significant.     

The role of chaos in poverty and children's socioemotional adjustment

There are growing levels of chaos in the lives of American children, youth, and families. Increasingly, children grow up in households lacking in structure and routine, inundated by background stimulation from noise and crowding, and forced to contend with the frenetic pace of modern life. Although widespread, chaos does not occur randomly in the population. We document that low-income adolescents face higher levels of chaos than their more affluent counterparts and provide longitudinal evidence that some of the adverse effects of poverty on socioemotional adjustment are mediated by exposure to chaotic living conditions.     

Development of a school-based treatment program for middle school youth with ADHD

The authors conduct an evaluation of a middle school-based treatment program for youth with ADHD during early stages of treatment development. The studies focus on interpreting outcome trends in preliminary data and identifying assessment issues that will be important to consider when conducting a clinical trial. Parent reports indicate that the majority of students benefit from improvements in academic, social, and overall functioning. Although teachers report beneficial effects for the majority of the participants in the program, there is little agreement about individual students. Measurement problems are associated with understanding normal change during a school year, accounting for normal behavior changes in December and May, and considerable disagreement between teachers. Suggestions to guide future work in this area are provided.