The intervention selection bias: an underrecognized confound in intervention research

Selection bias can be the most important threat to internal validity in intervention research, but is often insufficiently recognized and controlled. The bias is illustrated in research on parental interventions (punishment, homework assistance); medical interventions (hospitalization); and psychological interventions for suicide risk, sex offending, and juvenile delinquency. The intervention selection bias is most adequately controlled in randomized studies or strong quasi-experimental designs, although recent statistical innovations can enhance weaker designs. The most important points are to increase awareness of the intervention selection bias and to systematically evaluate plausible alternative explanations of data before making causal conclusions.     

Proneness to romantic jealousy and responses to jealousy in others

An experiment was conducted to assess the relationship between dispositional proneness to experience romantic jealousy and perceptions of jealousy in others On the basis of cognitive and motivational constructs, it was hypothesized that (1) Persons high in proneness to jealousy perceive healthy jealous couples as more in love than healthy nonjealous couples, (2) persons high in proneness to jealousy perceive unhealthy jealous couples as less in love than unhealthy nonjealous couples, and (3) persons low in proneness to jealousy perceive healthy jealous couples as less in love than healthy nonjealous couples The latter two hypotheses were supported Results were discussed with regard to the roles of beliefs about jealousy and threats to the perceiver in individuals reactions to jealousy in others     

Modular cognitive-behavioral therapy for body dysmorphic disorder

This study pilot tested a newly developed modular cognitive–behavioral therapy (CBT) treatment manual for body dysmorphic disorder (BDD). We tested feasibility, acceptability, and treatment outcome in a sample of 12 adults with primary BDD. Treatment was delivered in weekly individual sessions over 18 or 22 weeks. Standardized clinician ratings and self-report measures were used to assess BDD and related symptoms pre- and posttreatment and at 3- and 6-month follow-ups. At posttreatment, BDD and related symptoms (e.g., mood) were significantly improved. Treatment gains were maintained at follow-up. A relatively low drop-out rate, high patient satisfaction ratings, and patient feedback indicated that the treatment was highly acceptable to patients. To our knowledge, this represents the first test of a broadly applicable, individual psychosocial treatment for BDD.     

The properties of geophysical fields and their effects on elephants and other animals

Geophysical properties of acoustic, seismic, electric, and magnetic waveforms create opportunities and constraints for animals' communication and sensory monitoring of the environment. The geometric spreading of waves differs; at some frequencies, transmission is most efficient and has minimal noise. The spreading properties of seismic waves favor long-distance propagation for communication and environmental monitoring, and would benefit elephants (Elephas maximus and Loxodonta africana), such as in locating subsurface water. Extending C. E. O'Connell-Rodwell, B. T. Amason, and L. A. Hart (2000), a man jumping at 1.11 km propagated seismic waves at 10-40 Hz. Given the noise of lightning and the Schumann resonances, near field magnetic and electric transmission by animals would be most efficient around 1000 Hz.     

Context Specificity of Excitation and Inhibition in Ambiguous Stimuli

Two experiments examined the susceptibility of excitation and inhibition to contextual change when the conditioned stimulus (CS) was ambiguous using an appetitive conditioning paradigm. In Experiment 1, excitation to a CS was lost with a context switch when inhibition had been learned to the CS in a prior feature-negative (FN) discrimination. Control groups that had received either more or less excitatory conditioning in the absence of inhibitory pretraining showed no loss. In Experiment 2 inhibition was lost with a context switch in a group that had received excitatory and then inhibitory conditioning with the CS. No loss was observed in a group that had not received excitatory pretraining. The results suggest that contexts are especially likely to control performance to ambiguous CSs when they can modulate the second of two learned associations. Results are discussed in terms of their implications for occasion setting and modern conditioning theory.     

Evidence for processing of constituent singleand multiletter codes: Support for multilevel coding in word perception

This investigation assessed whether constituent codes are activated during word processing. In two experiments, a priming procedure was used to test whether printed word primes facilitate skilled readers’ identification of subsequently presented letter and letter bigram targets appearing in the primes (present condition), relative to the same targets not appearing in the primes (absent condition). Experiment 1 demonstrated the priming of single-letter targets and indicated that priming effects are facilitative and not inhibitory. In Experiment 2, high- and low-frequency bigram targets appearing in word primes were shown to have a processing advantage over bigram targets not appearing in word primes. Single-letter constituents in low-frequency bigrams also benefited from priming; however, single letters in high-frequency bigrams showed no such benefit. The results in general suggest that both single- and multiletter constituents are available during word processing, and hence support multicomponent models of word perception.     

The role of dopamine in reinforcement: changes in reinforcement sensitivity induced by D1-type, D2-type, and nonselective dopamine receptor agonists

Dose-dependent changes in sensitivity to reinforcement were found when rats were treated with low, moderate, and high doses of the partial dopamine D1-type receptor agonist SKF38393 and with the nonselective dopamine agonist apomorphine, but did not change when rats were treated with similar doses of the selective dopamine D2-type receptor agonist quinpirole. Estimates of bias did not differ significantly across exposure to SKF38393 or quinpirole, but did change significantly at the high dose of apomorphine. Estimates of goodness of fit (r2) did not change significantly during quinpirole exposure. Poor goodness of fit was obtained for the high doses of SKF38393 and apomorphine. Decrements in absolute rates of responding were observed at the high dose of quinpirole and at the moderate and high doses of SKF38393 and apomorphine. Changes in r2 and absolute responding may be due to increases in stereotyped behavior during SKF38393 and apomorphine exposure that, in contrast to quinpirole, were distant from the response lever. The present data provide evidence that sensitivity to reward is affected more strongly by dopamine D1-like receptors rather than D2-like receptors, consistent with evidence from other studies investigating consummatory dopamine behavior and the tonic/phasic dopamine hypothesis.     

Ethnic identity and acculturation in Hispanic early adolescents: mediated relationships to academic grades, prosocial behaviors, and externalizing symptoms

This study examined acculturative stress and self-esteem as mediators of the association of ethnic identity and acculturation with psychosocial outcomes. The study sample consisted of 347 Hispanic adolescents in a "new" immigrant-receiving community in the Midwest. The authors expected acculturation to influence psychosocial adjustment through acculturative stress and ethnic identity to influence psychosocial adjustment through self-esteem. Results indicated that relationships of ethnic identity to academic grades and to externalizing symptoms were mediated by self-esteem and that both U.S. and Hispanic acculturation orientations were directly associated with prosocial behavior. The relationships of U.S. cultural orientation to academic grades and to behavior problems were mediated through acculturative stress and self-esteem. Implications of these findings for the study of Hispanics in more monocultural receiving communities are discussed.