Stroop Inhibition Research Articles

Comparison of impulsivity and working memory in cocaine addiction and pathological gambling: Implications for cocaine-induced neurotoxicity

BackgroundThe aim of this study was to compare the cognitive performance of cocaine dependent individuals (CDI) with that of pathological gamblers (PG). Cocaine dependence and pathological gambling share neurobiological vulnerabilities related to addiction, but PG are relatively free of the toxic consequences, such that any additional deficits observed in CDI may be interpreted as pertaining to specific drug effects. MethodsWe used a case–control observational design contrasting multiple measures of impulsivity (UPPS-P trait impulsivity, delay discounting) and executive measures of response inhibition (Stroop) and working memory performance (N-back) between groups of CDI (n=29), PG (n=23), and healthy controls (n=20). We conducted one-way ANOVAs, followed by planned pairwise tests and calculations of Cohen's d to estimate significant differences between the groups. ResultsCDI, as compared to PG, had elevated scores on UPPS-P Negative Urgency and poorer performance on working memory (2-back). PG had steeper delay-discounting rates. Both groups had elevated Positive Urgency and poorer Stroop inhibition compared to controls. Peak amount of cocaine use was negatively correlated with working memory and response inhibition performance. ConclusionWe found cocaine-related specific elevations in Negative Urgency and working memory deficits, putatively identified as cocaine neurotoxicity effects. Other aspects of impulsivity (Positive Urgency, Stroop inhibition) were increased across CDI and PG groups and may reflect vulnerability factors for addiction.

Anti-Saccade Performance Predicts Executive Function and Brain Structure in Normal Elders

To assess the neuropsychological and anatomical correlates of anti-saccade (AS) task performance in normal elders. The AS task correlates with neuropsychological measures of executive function and frontal lobe volume in neurological diseases, but has not been studied in a well-characterized normal elderly population. Because executive dysfunction can indicate an increased risk for cognitive decline in cognitively normal elders, we hypothesized that AS performance might be a sensitive test of age-related processes that impair cognition. The percentage of correct AS responses was evaluated in 48 normal elderly subjects and associated with neuropsychological test performance using linear regression analysis and gray matter volume measured on magnetic resonance imaging scans using voxel-based morphometry. The percentage of correct AS responses was associated with measures of executive function, including modified trails, design fluency, Stroop inhibition, abstraction, and backward digit span, and correlated with gray matter volume in 2 brain regions involved in inhibitory control: the left inferior frontal junction and the right supplementary eye field. The association of AS correct responses with neuropsychological measures of executive function was strongest in individuals with fewer years of education. The AS task is sensitive to executive dysfunction and frontal lobe structural alterations in normal elders.

Differential effects of emotional information on interference task performance across the life span

While functioning in multiple domains declines with age, emotional regulation appears to remain preserved in older adults. The Emotion Inhibition (Emotional Stroop) Test requires participants to name the ink color in which neutrally and emotionally valenced words are printed. It was employed in the current investigation as a measure of affective regulation in the context of an interference task in relation to age. Results demonstrated that while participants ranging from 20 to 50 years of age performed significantly worse on the emotion Stroop Inhibition relative to the neutral Stroop Inhibition condition, subjects over 60 years of age displayed the converse of this pattern, performing better on the emotion than the neutral condition, suggesting that they are less affected by the emotional impact of the positive and negative words used in the former condition. This pattern of age-related change in the ability to manage emotion may be related to blunting of affective signaling in limbic structures or, at the psychological level, focusing on emotional regulation.

Inhibition and facilitation in schizotypy

Participants scoring high and low on a schizotypy scale (n = 18 in each group) switched between naming words and naming colors in a Stroop task in congruent, neutral, and incongruent conditions. The findings were that, while being slower and less accurate overall than low schizotypes, the high schizotypy group did not display disproportionately greater Stroop inhibition or facilitation, suggesting intact selective attention. However, the high schizotypy group suffered disproportionately larger switching costs. The results provide evidence for similarities between schizotypy and schizophrenia, specifically that the problem in schizotypy is to do with switching rather than selecting attention, because of a difficulty either in selecting task-relevant information or in inhibiting inappropriate response alternatives.

Immediate and Delayed Cognitive Responses to Moderate Intensity Physical Activity in Older Adults

Research on acute bouts of exercise is scarce and is limited by a focus on special populations and the failure to include a control condition. In addition, no research with any population has tested the duration of cognitive improvements as a function of the amount of time since an acute bout of exercise. PURPOSE: Therefore, the purpose of this study was to test the immediate and delayed effects of an acute bout of moderate intensity exercise on cognitive function in healthy older adults. Cognitive function was assessed using three conditions of the Stroop task. All three conditions of the Stroop task required participants to identify the color of visual stimuli. In the control condition the stimuli were neutral, in the interference condition the stimuli were color names, and in the inhibition condition the stimuli were color names and the color of each word was the same as the color name on the previous stimulus. METHODS: Older community-dwelling adults (60–90 yrs) who were self-reported to be healthy and had no diagnosed cognitive impairments, were randomly assigned to the exercise condition (5-min warm-up and 20 minutes of walking at 60% age-predicted HRR) or the control condition (25 minutes of sitting quietly). All three conditions of the Stroop task were administered at 13 test times (baseline and 12 post-treatment times: immediately, 5-, 10-, 15-, 20-, 30-, 45-, 60-, 75-, 90-, 105-, and 120-min post-treatment) in a random, counter-balanced order. Reaction times were analyzed using a mixed design analysis of variance with repeated measures on time, with treatment as the between-groups variable, and with baseline reaction time as a covariate. RESULTS: For the Stroop control and Stroop interference conditions, there were no significant effects. However, for the Stroop inhibition condition, there was a significant interaction of condition by time, F(11,88)=2.31, p <.02. An examination of the data demonstrated that the control group performed more quickly than the exercise group at every time point beginning at 5-min post-exercise. CONCLUSIONS: When inhibition is facilitated, performance on the inhibition condition should be slower. Therefore, although counter-intuitive, these results suggest that an acute bout of exercise has a beneficial effect on the inhibitory processes of older adults (as demonstrated by slower performance on the inhibition condition of the Stroop). Further, the time course of this effect is such that it is apparent 5-min post-exercise and lasts for up to 2 hours post exercise. Thus, it is concluded that a 5-min warm-up and 20-min of moderate intensity exercise benefit the inhibitory functions of older adults for 2-hrs following the exercise bout.

Suggestion Reduces the Stroop Effect

We examined the effects of suggestion on Stroop interference in highly suggestible individuals. Participants completed the Stroop task with and without a suggestion to perceive Stroop words as meaningless symbols. Half the participants were given this suggestion in hypnosis, and half were given the suggestion without the induction of hypnosis. Suggestion produced a significant reduction in Stroop inhibition, accounting for about 45% of the variance in Stroop responding, regardless of whether hypnosis had been induced. These findings indicate that suggestion can at least partially overcome the automaticity associated with the Stroop effect.

Context effects in Stroop-like word and picture processing.

Presents a series of 6 experiments in which Stroop-like effects were generated by modally pure color-color, picture-picture, and word-word stimuli instead of the usual modally mixed color-word or picture-word stimuli. Naming, reading, and categorization tasks were applied. The Stroop inhibition was preserved with these stimuli but unexpectedly showed a semantic gradient only in the naming and not in the reading task. Word categorizing was slower and more interference prone than picture categorizing. These and other results can be captured by a model with two main assumptions: (a) semantic memory and the lexicon are separate, and (b) words have privileged access to the lexicon, whereas pictures and colors have privileged access to the semantic network. Such a model is developed and put to an initial test.