The persistence of attention-deficit/hyperactivity disorder into young adulthood as a function of reporting source and definition of disorder

This study examined the persistence of attention-deficit/hyperactivity disorder (ADHD) into young adulthood using hyperactive (N = 147) and community control (N = 71) children evaluated at ages 19-25 years. ADHD was rare in both groups (5% vs. 0%) based on self-report but was substantially higher using parent reports (46% vs. 1.4%). Using a developmentally referenced criterion (+2 SD), prevalence remained low for self-reports (12% vs. 10%) but rose further for parent reports (66% vs. 8%). Parent reports were more strongly associated with major life activities than were self-reports. Recollections of childhood ADHD showed moderate correlations with actual parent ratings collected in childd hood, which suggests some validity for such recollections. The authors conclude that previous follow-up studies that relied on self-reports might have substantially underestimated the persistence of ADHD into adulthood.     

GROUP FORAGING SENSITIVITY TO PREDICTABLE AND UNPREDICTABLE CHANGES IN FOOD DISTRIBUTION: PAST EXPERIENCE OR PRESENT CIRCUMSTANCES?

The ideal free distribution theory (Fretwell & Lucas, 1970) predicts that the ratio of foragers at two patches will equal the ratio of food resources obtained at the two patches. The theory assumes that foragers have "perfect knowledge" of patch profitability and that patch choice maximizes fitness. How foragers assess patch profitability has been debated extensively. One assessment strategy may be the use of past experience with a patch. Under stable environmental conditions, this strategy enhances fitness. However, in a highly unpredictable environment, past experience may provide inaccurate information about current conditions. Thus, in a nonstable environment, a strategy that allows rapid adjustment to present circumstances may be more beneficial. Evidence for this type of strategy has been found in individual choice. In the present experiments, a flock of pigeons foraged at two patches for food items and demonstrated results similar to those found in individual choice. Experiment 1 utilized predictable and unpredictable sequences of resource ratios presented across days or within a single session. Current foraging decisions depended on past experience, but that dependence diminished when the current foraging environment became more unpredictable. Experiment 2 repeated Experiment I with a different flock of pigeons under more controlled circumstances in an indoor coop and produced similar results.     

The formation of a generalized categorization repertoire: effect of training with multiple domains,samples, and comparisons

The present experiment explored the effects of three variables on the spontaneous categorization of stimuli in perceptually distinct and novel domains. Each of six stimulus domains was created by morphing two images that were the domain endpoints. The endpoints of the domains were male and female faces, two abstract drawings, a car and a truck, two banded-elevation satellite land images, a tree and a cat, and two false-color satellite images. The stimulus variants at each end of a domain defined two potential perceptual classes. Training was conducted in a matching-to-sample format and used stimuli from one or two domains, one or three variants per class as samples, and one or three variants per class as comparisons. The spontaneous categorization of stimuli in the untrained stimulus domains showed the emergence of a generalized categorization repertoire. The proportion of spontaneously categorized stimuli in the new domains was positively related to the number of domains and samples used in training, and was inversely related to the number of comparisons used in training. Differential reaction times demonstrated the discriminability of the stimuli in the emergent classes. This study is among the first to provide an empirical basis for a behavior-analytic model of the development of generalized categorization repertoires in natural settings.     

Empathy and generalized reciprocity in compliance with requests for help

This study examined empathy and reciprocity as explanations for why people comply with requests for help. Participants (35 male and 62 female) imagined being asked for money by a person who had locked keys in a car and then reported how likely they would he to comply with such a request, whether they had previously locked their keys in their car (empathy), and, if so, whether they had been helped (reciprocity). In support of the explanation based on empathy, people who reported previously locking their keys in their cars indicated being more likely to comply.     

The Infrequency-Posttraumatic Stress Disorder scale (Fptsd) for the MMPI-2: development and initial validation with veterans presenting with combat-related PTSD

Researchers have identified difficulties associated with the use of traditional Minnesota Multiphasic Personality Inventory-2 (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) validity scales with survivors of traumatic events. A new scale, the Infrequency-Posttraumatic Stress Disorder scale (Fptsd), was created from MMPI-2 items that were infrequently endorsed by 940 male combat veterans presenting for treatment at the posttraumatic stress disorder (PTSD) clinics of 2 Veterans Affairs Medical Centers. A variety of statistical methods were implemented that preliminarily established Fptsd's validity with a validation sample of 323 additional PTSD-diagnosed combat veterans. Results indicate that, relative to previously established validity and overreporting scales (F, Fb, and Fp), Fptsd was significantly less related to psychopathology and distress and better at discriminating simulated from genuinely reported PTSD. Clinical implications are discussed concerning the use of Fptsd to assess disability-seeking veterans suspected of overreporting PTSD symptoms.     

Accountability as a deterrent to self-enhancement: the search for mechanisms

Although self-enhancement is linked to psychological benefits, it is also associated with personal and interpersonal liabilities (e.g., excessive risk taking, social exclusion). Hence, structuring social situations that prompt people to keep their self-enhancing beliefs in check can confer personal and interpersonal advantages. The authors examined whether accountability can serve this purpose. Accountability was defined as the expectation to explain, justify, and defend one's self-evaluations (grades on an essay) to another person ("audience"). Experiment 1 showed that accountability curtails self-enhancement. Experiment 2 ruled out audience concreteness and status as explanations for this effect. Experiment 3 demonstrated that accountability-induced self-enhancement reduction is due to identifiability. Experiment 4 documented that identifiability decreases self-enhancement because of evaluation expectancy and an accompanying focus on one's weaknesses.     

Deriving the loudness exponent from categorical judgments

The power function exponent for loudness is traditionally determined by means of a process of magnitude estimation. It is demonstrated in this paper that the exponent can also be obtained by using the procedure of absolute identification of sound intensity. It has been shown that subjects' responses to tones of a given intensity are distributed in a normal distribution whose variance depends on the range, R, over which the tones are distributed. By means of a standard statistical transformation, the normal density in log space is converted to the corresponding probability density in linear space. The power function exponent can then be obtained directly from the linear probability density. We also suggest that there is a direct relationship between the information calculated from experiments on absolute identification of sound intensity and the neurophysiological, poststimulus histogram measured in a nerve fiber in the auditory nerve.     

The Fisher-Pitman permutation test: an attractive alternative to the F test

The Fisher-Pitman permutation test is shown to possess significant advantages over conventional alternatives when analyzing differences among independent samples with unequal variances.