Biomedical subjects

Nader Amir

Publications and source records attributed to Nader Amir.

6 recordsLinked to original sources

PubMed2005

Increased activation of the anterior cingulate cortex during processing of disgust faces in individuals with social phobia.

BACKGROUND: Researchers have examined the role of differential activation of various brain regions involved in processing emotional information in subjects with social phobia. These studies have focused mostly on the activation of the amygdala. The anterior cingulate cortex (ACC) also has been implicated in processing emotional information, but its role in social phobia has not been examined. METHODS: We recruited subjects with social phobia and matched them with non-anxious control subjects. Participants viewed facial expressions of disgust ("disgust faces") and neutral facial expressions ("neutral faces"). We measured brain activation, focusing on the ACC, using functional magnetic resonance imaging. We also recorded participants' ratings of emotional valence of faces, as well as response latencies to make these valence judgments. We repeated this procedure using three different sets of facial expressions. RESULTS: Individuals with social phobia exhibited a significant increase in ACC activity compared with non-anxious control subjects when processing disgust versus neutral faces. Additionally, compared with control subjects, subjects with social phobia were faster in their ratings of disgust faces and rated the neutral faces more negatively. CONCLUSIONS: Our findings demonstrate that the ACC might be involved in affective processing of negative information in socially phobic subjects.

Adult↗

PubMed2005

Resolving ambiguity: the effect of experience on interpretation of ambiguous events in generalized social phobia.

The authors examined the effect of learning on multiple encounters with sources of social ambiguity in individuals with generalized social phobia (GSP). The authors modified G. B. Simpson and H. Kang's (1994) paradigm and presented prime-target word pairs to individuals with GSP and nonanxious controls (NACs) to prime threat and nonthreat meanings of homographs and examine the effect of this priming on later encounters with that homograph. Consistent with previous research, NACs showed faster response latencies naming a target primed by a homograph with the same meaning activated in two successive trials than naming the same target primed by an unrelated word. Furthermore, NACs showed slower response latencies naming a target when a different meaning of the homograph prime was activated in successive trials than naming a target primed by an unrelated word. GSP participants did not show this pattern in learning a nonthreat meaning of a homograph. These results support the hypothesis that a faulty learning mechanism may be involved in social anxiety.

Adult↗

PubMed2005

The taxometrics of marriage: is marital discord categorical?

This study used taxometric methods to investigate the latent structure of the construct of marital adjustment as indexed by the Marital Adjustment Test (MAT; H. J. Locke & K. M. Wallace, 1959). That is, the authors examined whether marital adjustment is best thought of as a "dimension" of adjustment only or whether there also are categorical differences between "discordant" and "nondiscordant" couples. Analyses of data provided by 447 couples married for approximately 2 years provided converging evidence for a latent category of marital discord, suggesting that marital discord can be viewed as a qualitatively distinct state experienced by approximately 20% of the couples in the current sample. Implications for marital assessment are outlined.

Adolescent↗

PubMed2005

Can sample-specific simulations help detect low base-rate taxonicity?

The authors examined the role of the sample-specific simulations (SSS; A. M. Ruscio & J. Ruscio, 2002; J. Ruscio & A. M. Ruscio, 2004) procedure in detecting low base-rate taxa that might otherwise prove elusive. The procedure preserved key distributional characteristics for moderate to high base-rate taxa, but it performed inadequately for low base-rate taxa, with low to moderate nuisance covariance, decreasing indicator validity, and increasing average nuisance covariance. Visual inspection of the curves produced by the SSS procedure, combined with the expectation that the inchworm test should produce a clear peak for low base-rate taxonic samples, led to inappropriate conclusions about the suitability of data. The authors speculate that examination of low base-rate taxa using SSS may require other algorithms for generating comparison distributions, consideration of the shape of the whole curve, and/or relaxation of the expectation that a clear peak will emerge with the inchworm test.

Algorithms↗

PubMed2003

Is depression taxonic, dimensional, or both?

The current investigation examines the potential importance of item selection in the ongoing discussion regarding the taxonicity of depression. Following J. C. Coyne (1994), we contrast the taxonicity of "distress" with the taxonicity of a syndrome more focused on somatic symptoms (i.e., the involuntary defeat syndrome). Using 4 samples of 984 undergraduates, we first replicate the J. Ruscio and A. M. Ruscio (2000) results by showing that distress item indicators are dimensional. We then demonstrate taxonicity using items focused on somatic symptoms and reflective of disruption of multiple homeostatic mechanisms. Results suggest that item selection is central to the determination of taxonicity in depression.

Depression↗

PubMed2002

Inflated perception of responsibility for harm in OCD patients with and without checking compulsions: a replication and extension.

In a follow-up study to [J. Anxiety Disord., in press] examination of inflated perception of responsibility for harm among individuals with obsessive compulsive disorder (OCs), 22 OC checkers, 24 OC non-checkers, and 25 non-anxious controls (NACs) completed the Obsessive Compulsive Responsibility Scale (OCRS), which consisted of written descriptions of Low-Risk (LR), Moderate-Risk (MR), and High-Risk (HR) scenarios. In LR and MR scenarios, OC checkers reported greater perception of responsibility for harm and greater relief upon rectifying the situation, than did NACs. OC checkers also reported greater urges to rectify LR situations than did NACs. OC non-checkers did not differ from NACs on any of the scales. No group differences emerged for HR scenarios. The results suggest that, compared to OC non-checkers and to NACs, OC checkers have an inflated perception of responsibility for harm; and that this perception leads to a need to rectify potentially harmful situations.

Analysis of Variance↗