The perils of partialling: cautionary tales from aggression and psychopathy

Although a powerful technique, the partialling of independent variables from one another in the context of multiple regression analysis poses certain perils. The present article argues that the most important and underappreciated peril is the difficulty in knowing what construct an independent variable represents once the variance shared with other independent variables is removed. The present article presents illustrative analyses in a large sample of inmates (n=696) using three measures from the psychopathy and aggression fields. Results indicate that in terms of relations among items on a single scale and relations between scales, the raw and residualized scores bore little resemblance to one another. It is argued that researchers must decide to which construct-the one represented by the original scale or the one represented by the residualized scale-conclusions are meant to apply. Difficulties in applying the conclusions to the residualized scale are highlighted and best practices suggested.     

Orientation discrimination across the visual field: size estimates near contrast threshold

Performance in detection and discrimination tasks can often be made equal across the visual field through appropriate stimulus scaling. The parameter E2 is used to characterize the rate at which stimulus dimensions (e.g., size or contrast) must increase in order to achieve foveal levels of performance. We calculated both size and contrast E2 values for orientation discrimination using a spatial scaling procedure that involves measuring combination size and contrast thresholds for stimuli with constant size-to-contrast ratios. E2 values for size scaling were 5.77 degrees and 5.92 degrees. These values are three to four times larger than those recovered previously using similar stimuli at contrasts well above detection threshold (Sally & Gurnsey, 2003). E2 values for contrast scaling were 324.2 degrees and 44.3 degrees, indicating that for large stimuli little contrast scaling (.3% to 2.3% increase) was required in order to equate performance in the fovea and the largest eccentricity (10 degrees). A similar pattern of results was found using a spatial scaling method that involves measuring contrast thresholds for target identification as a function of size across eccentricities. We conclude that the size scaling for orientation discrimination at near-threshold stimulus contrasts is much larger than that required at suprathreshold contrasts. This may arise, at least in part, from contrast-dependent changes in mechanisms that subserve task performance.     

Extinction of conditioned odor potentiation of startle

Several recent studies with rats (Sprague-Dawley strain) have documented that an odor previously paired with shock potentiates the acoustic startle response, a phenomenon referred to as conditioned odor potentiation of startle (OPS). A surprising finding in these studies was that OPS did not extinguish even though the odor was present throughout the 25-min test session. Therefore, the present study more fully examined extinction of OPS. The results of Experiment 1, which employed both within-subject and between-group comparisons, showed that extinction of OPS occurred in adult rats only after several days of testing. Experiment 2 used the between-group procedure and found similar results with 23-day-old rats, the youngest age that exhibits the OPS effect. Experiment 2 also showed that giving rats 15 odor-shock pairings at 16 days of age, an age where they acquire the odor-shock association but cannot express it via OPS, does not increase subsequent resistance to extinction following odor-shock pairings at 23 days of age. Taken together, the results of this study show that (1) although OPS is somewhat resistant to extinction, it does extinguish with repeated tests and (2) suggests that there are no age differences in the rate of extinction of OPS.     

The Value of Lakota Traditional Healing for Youth Resiliency and Family Functioning

This article reports research findings on the impact of Oglala Lakota Sioux traditional healing on family functioning and youth resiliency where trauma, abuse, or violence are often present. Caregivers of Lakota youth struggling with serious emotional and behavioral problems participated in the study. The study included both quantitative and qualitative samples: 27 families for the quantitative sample and 8 families for the qualitative sample. Results from caregivers revealed that traditional healing and cultural practices, as well as the promotion of cultural identity, had statistically significant positive effects on the perceived familial and individual functioning of Lakota youth and their families. Effect sizes indicate that the results have strong practical significance.     

The benefits of retail therapy: Making purchase decisions reduces residual sadness

People often shop when feeling sad, but whether and why shopping reduces residual (lingering) sadness remains an open question. Sadness is strongly associated with a sense that situational forces control the outcomes in one's life, and thus we theorized that the choices inherent in shopping may restore personal control over one's environment and reduce residual sadness. Three experiments provided support for our hypothesis. Making shopping choices helped to alleviate sadness whether they were hypothetical (Experiment 1) or real (Experiment 2). In addition, all experiments found support for the underlying mechanism of personal control restoration. Notably, the benefits of restored personal control over one's environment do not generalize to anger (Experiments 2 and 3), because anger is associated with a sense that other people (rather than situational forces) are likely to cause negative outcomes, and these appraisals are not ameliorated by restoring personal control over one's environment.     

Explicit awareness supports conditional visual search in the retrieval guidance paradigm

In four experiments we explored whether participants would be able to use probabilistic prompts to simplify perceptually demanding visual search in a task we call the retrieval guidance paradigm. On each trial a memory prompt appeared prior to (and during) the search task and the diagnosticity of the prompt(s) was manipulated to provide complete, partial, or non-diagnostic information regarding the target's color on each trial (Experiments 1–3). In Experiment 1 we found that the more diagnostic prompts was associated with faster visual search performance. However, similar visual search behavior was observed in Experiment 2 when the diagnosticity of the prompts was eliminated, suggesting that participants in Experiment 1 were merely relying on base rate information to guide search and were not utilizing the prompts. In Experiment 3 participants were informed of the relationship between the prompts and the color of the target and this was associated with faster search performance relative to Experiment 1, suggesting that the participants were using the prompts to guide search. Additionally, in Experiment 3 a knowledge test was implemented and performance in this task was associated with qualitative differences in search behavior such that participants that were able to name the color(s) most associated with the prompts were faster to find the target than participants who were unable to do so. However, in Experiments 1–3 diagnosticity of the memory prompt was manipulated via base rate information, making it possible that participants were merely relying on base rate information to inform search in Experiment 3. In Experiment 4 we manipulated diagnosticity of the prompts without manipulating base rate information and found a similar pattern of results as Experiment 3. Together, the results emphasize the importance of base rate and diagnosticity information in visual search behavior. In the General discussion section we explore how a recent computational model of hypothesis generation (HyGene; Thomas, Dougherty, Sprenger, & Harbison, 2008), linking attention with long-term and working memory, accounts for the present results and provides a useful framework of cued recall visual search.     

Optimizing Contingency Management With Methamphetamine-Using Men Who Have Sex With Men

Among men who have sex with men (MSM), methamphetamine use is associated with multiple, overlapping syndemic conditions including increased risk for HIV seroconversion and onward HIV transmission. Contingency management (CM) is an evidence-based behavioral intervention implemented to curb methamphetamine use and optimize HIV/AIDS prevention among MSM in San Francisco since 2003. We conducted a program evaluation to document the evolution of this 12-week CM program to include delivery of brief, individual counseling incorporating motivational interviewing and behavioral skills. A drop-in group delivered concurrently with CM urine-screening visits also provides peer support as well as referrals for other social and medical services. From December 2011–October 2013, a total of 131 clients enrolled in the CM program and provided a median of 22 urine samples (Interquartile Range = 10–34) that were nonreactive for methamphetamine. Findings support the feasibility and acceptability of integrating individual and group counseling with community-based CM for methamphetamine-using MSM.