Bias in the use of base rates: Racial prejudice in decision-making

Two studies investigated biases in the use of base rate information when assessing the probability of a witness' accurate identification of a white or West Indian as a burglar. An adapted version of the Kahneman-Tversky cab problem was used, to provide a social decision in which biases could be measured against some normative standard. Ethnicity of youth (white/West Indian) and nature of base rate (incidental/causal) were manipulated in a 2 × 2 between-subjects design. A significant interaction effect revealed that subjects took no account of the base rate for a West Indian subject, but used the base rate only when it was causal and the youth was white. This ‘prejudice effect’ against a West Indian youth and ‘exoneration effect’ for a white youth were replicated in a second study, using a microcomputer and chronometric analyses. Results are discussed in terms of heuristic decision-making, social schemata, and the cognitive versus motivational bases of bias in the use of base rates.     

Insight-oriented group psychotherapy of latency-age children in an acute care setting

Traditional approaches to group therapy with latency-age children have stressed activity and nonverbal therapeutic interventions. These approaches originated in the 1940s with Slavson's activity aroup therapy. A review of the literature of the past 25 years reveals that many clinicians have increasingly employed verbal techniques with latencyage groups. Most such reports describe groups for latency-age out-patients. In this paper, a verbal, interpretive technique for group therapy with latency-age inpatients is described. Clinical vignettes are included to illustrate this technique. Our experience suggests that such a technique can become an integral part of the inpatient treatment program for the latency-age child.     

Failure of acute and chronic administration of Δ9-tetrahydrocannabinol to affect the repeated acquisition of serial position responses in pigeons

Pigeons were trained to acquire a new four-response position sequence each day by pecking three response keys in a predetermined order. The key color varied after each correct response prior to food delivery. Acute administration of Γ⁹-tetrahydrocannabinol (Δ⁹-THC) up to a dose that completely eliminated responding, had no effect on total acquisition errors, or on within session patterns of error elimination. Chronic administration of Δ⁹-THC (3–10 mg/kg/day), either before or after the session for 4–7 weeks, also did not affect these error measures, although rates of responding were markedly suppressed and at times no responding occurred Discontinuation of Δ⁹-THC administration for periods of 4–6 weeks also was without effect on errors. These experiments suggest that neither acute nor chronic Δ⁹-THC produce specific effects on the repeated acquisition of serial position responses in pigeons.     

On the Relation Between Time Perception and the Timing of Motor Action: Evidence for a Temporal Oscillator Controlling the Timing of Movement

Studies of time estimation have provided evidence that human time perception is determined by an internal clock containing a temporal oscillator and have also provided estimates of the frequency of this oscillator (Treisman, Faulkner, Naish, & Brogan, 1992; Treisman & Brogan, 1992). These estimates were based on the observation that when the intervals to be estimated are accompanied by auditory clicks that recur at certain critical rates, perturbations in time estimation occur. To test the hypothesis that the mechanisms that underlie the perception of time and those that control the timing of motor performance are similar, analogous experiments were performed on motor timing, with the object of seeing whether evidence for a clock would be obtained and if so whether its properties resemble those of the time perception clock. The prediction was made that perturbations in motor timing would be seen at the same or similar critical auditory click rates. The experiments examined choice reaction time and typing. The results support the hypothesis that a temporal oscillator paces motor performance and that this oscillator is similar to the oscillator underlying time perception. They also provide an estimate of the characteristic frequency of the oscillator.     

A note on russell's paradox in locally cartesian closed categories

Working in the fragment of Martin-Löfs extensional type theory [12] which has products (but not sums) of dependent types, we consider two additional assumptions: firstly, that there are (strong) equality types; and secondly, that there is a type which is universal in the sense that terms of that type name all types, up to isomorphism. For such a type theory, we give a version of Russell's paradox showing that each type possesses a closed term and (hence) that all terms of each type are provably equal. We consider the kind of category theoretic structure which corresponds to this kind of type theory and obtain a categorical version of the paradox. A special case of this result is the degeneracy of a locally cartesian closed category with a morphism which is generic in the sense that every other morphism in the category can be obtained from it via pullback.The financial support of the Royal Society in London is gratefully acknowledged.     

Chest pain without coronary artery disease: An exploratory comparison with panic disorder

Recent reports have indicated similarities between patients with persistent chest pain of nonorganic origin and patients with panic disorder. In order to explore this association further, we administered a structured interview and three self-report measures (State-Trait Inventory, Beck Depression Inventory, and SCL90-R) to three subject groups: (1) a sample with persistent chest pain (CP; n=14) who had been screened and found to have normal coronary arteries, (2) a sample of patients with panic disorder (PD; n=14), and (3) a sample of matched normals (n=14). CP patients were considered to be free of coronary artery disease (CAD) following normal cardiac catheterization and/or normal thallium stress tests and were not diagnosed initially with panic disorder. PD patients were diagnosed with a standardized psychiatric interview and were free of organic causes of panic. Using an exploratory data analytic approach, the results indicated that both CP and PD samples reported increased levels of state and trait anxiety (p <.0001), depression (p <.01), and somatization (p <.0001) compared with normals. CP patients differed from PD patients in their less frequent use of anxiolytic medication (p <.01) and lower levels of reported panic anxiety and phobic avoidance (p <.0001). These data suggest that persistent chest pain in the absence of CAD shares some features with panic disorder, yet differs from panic in key ways as well. The results are discussed in light of the role of anxiety in contributing to symptom labeling.This research was supported by Grant 86G-491 from the American Heart Association, Texas Affiliate, to J.G.B. H.T. is the recipient of USPHS Research Career Development Award K04-HL-0122246.