Angeles F. Estévez

Impulsivity differences in recreational cannabis users and binge drinkers in a university population

BACKGROUND Recreational cannabis use and alcohol binge drinking are the most common drug consumption patterns in young adults. Impulsivity and several psychopathological signs are increased in chronic drug users, but the implications of recreational use are still poorly understood. METHODS We evaluated impulsivity, sensation-seeking traits, impulsive decision-making, inhibitory control and possible symptoms of depression, anxiety and psychosis in three groups of young university adults: recreational cannabis users (N=20), alcohol binge drinkers (N=22) and non-drug users (N=26). RESULTS The cannabis and binge drinking groups had increased scores for impulsivity and sensation-seeking traits. Both groups also exhibited increased impulsive decision-making on the two-choice task and the Iowa gambling task; however, only the cannabis group was significantly different from the non-drug group regarding inhibitory control (go/no-go and stop tasks). The cannabis and binge drinking groups did not show differences in the psychopathological symptoms evaluated. CONCLUSIONS Our observations of this population of non-dependent drug users are consistent with the increased impulsivity traits and behaviors that have been described previously in chronic drug abusers. In this study, compared to no drug use, the recreational use of cannabis was associated with a major dysfunction of the different facets of impulsive behaviors. However, alcohol binge drinking was related only to impulsive decision-making. These results suggest that impulsivity traits and behaviors are present not only in chronic drug abusers but also in recreational drug users. Future work should continue to investigate the long-term effects of these common consumption patterns on various impulsive behaviors and psychopathological symptoms.

Temperament and attention in the self-regulation of 7-year-old children

Abstract The present work assessed the implications of the posterior orienting and the anterior executive attentional networks on self-regulation abilities in children through studying the relations of 7-year-old children’s temperament characteristics to different forms of attentional control. Children were classified in terms of their temperament traits measured through the Children’s Behavior Questionnaire. Children carried out two Stroop tasks, with and without distracting stimuli, and flanker and Stroop interference effects were calculated as measures of the orienting and the executive attentional networks, respectively. Results indicated that children scoring high in Anger, Discomfort, Sadness (only girls) and Approach-Anticipation (only girls) showed a stronger flanker interference effect, exhibiting greater difficulty to filter out the non relevant information than children scoring low did. On the other hand, children scoring high in Activity Level and Impulsivity (only girls), and low in Inhibitory Control, showed a stronger Stroop interference effect, indicating less ability to suppress prepotent behaviors under instructions. Also, patterns of interactions between some pairs of scales revealed that negative emotionality and self-regulatory aspects of temperament predicted both Stroop and flanker interference performance.

Stroop interference and negative priming: Problems with inferences from null results

The Stroop color-naming effect has often been taken as evidence for the automaticity of word processing (MacLeod, 1991). Recently, Besner, Stolz, and Boutilier (1997) reported that coloring a single letter instead of the whole word eliminated the Stroop effect. From this finding, they concluded that word processing could not be purely automatic, since it can be prevented. We asked whether the elimination of the Stroop effect is sufficient evidence for concluding that the word is not processed. Combining Besner et al.’s manipulation with a negative-priming procedure, we found intact negative priming from the prime color word in the absence of a Stroop effect. This result clearly indicates that the meaning of the prime word was processed. The findings highlight the importance of using converging methods to evaluate lack of processing.

Differential Outcomes Effect in Children and Adults With Down Syndrome

In previous studies, researchers have demonstrated that learning of symbolic relations is facilitated when a particular outcome is associated with each relation to be learned. In the present study, we extend this differential outcomes procedure to children and adults with Down syndrome who had to learn a symbolic conditional discrimination task. Participants showed a better terminal accuracy and a faster learning of the task when the alternative correct responses were each followed by unique different outcomes than when nondifferential outcomes were arranged. These findings confirm that the differential outcomes procedure can be a useful tool to ameliorate discriminative learning deficits and demonstrate the benefits of this procedure for people with Down syndrome.

Word-based grouping affects the prime-task effect on semantic priming

Semantic priming between words is reduced or eliminated if a low-level task such as letter search is performed on the prime word (the prime task effect), a finding used to question the automaticity of semantic processing of words. This idea is critically examined in 3 experiments with a new design that allows the search target to occur both inside and outside the prime word. The new design produces the prime task effect (Experiment 1) but shows semantic negative priming when the target letter occurs outside the prime word (Experiments 2 and 3). It is proposed that semantic activation and priming are dissociable and that inhibition and word-based grouping are responsible for reduction of semantic priming in the prime task effect.

Enhancing challenged students' recognition of mathematical relations through differential outcomes training

Previous studies have reported that the differential outcomes procedure enhances learning and memory in special populations with cognitive deficits (see Goeters, Blakely, & Poling, 1992, for a review). In the present study we extend these findings to healthy adults who were asked to discriminate between the symbols “ > ” and “ < ” in mathematical statements. In Experiment 1, the performance of participants who showed difficulties in discriminating between these symbols was better (shorter response times) for the differential outcomes condition than for the nondifferential outcomes condition. In Experiment 2, the difficulty of the task was increased by using signed decimal numbers. Similar to Experiment 1, participants who initially had difficulties in discriminating between the symbols showed better performance (higher accuracy) for the differential outcomes condition than for the nondifferential outcomes condition, but only when both numbers were negative. These findings suggest that the differential outcomes procedure can be used to improve performance of challenged healthy adults on discrimination tasks with mathematical symbols and relations.

Enhancing recognition memory in adults through differential outcomes

It has been widely demonstrated that the differential outcomes procedure (DOP) facilitates both the learning of conditional relationships and the memory for the conditional stimuli in animal subjects. For conditional discriminations in humans, the DOP also produces an increase in the speed of acquisition and/or final accuracy. However, the potential facilitative effects of differential outcomes in human memory have not been fully assessed. In the present study, we aimed to test whether this procedure improves performance on a recognition memory task in healthy adults. Participants showed significantly better delayed face recognition when differential outcomes were used. This novel finding is discussed in the light of other studies on the differential outcomes effect (DOE) in both animals and humans, and implications for future research are presented.

Improving Delayed Face Recognition in Alzheimer's Disease by Differential Outcomes

OBJECTIVE Previous studies have demonstrated the benefit of the differential outcomes procedure (DOP) in human learning. In the present study we aimed to explore whether the DOP might also help to overcome the face recognition memory deficit commonly observed in Alzheimers disease (AD) patients. METHOD A delayed matching-to-sample task was used. Participants were instructed to choose which of the 4 alternative faces (comparison stimuli) matched the previously seen face (sample stimulus). Either short (5 seconds) or long (25 seconds) delays were interposed between the sample and the comparison stimuli. In the differential outcomes condition each sample face was paired with its own outcome. In contrast, in the nondifferential condition, outcomes were randomly arranged. RESULTS The differential outcomes effect (DOE) was evident in the AD patients with both accuracy and latency data. That is, they showed a significantly better and faster delayed face recognition when differential outcomes were arranged. The analyses also revealed a significant main effect of delay; participants were slower in the 25 seconds condition than in the 5 seconds condition, but the difference was higher in the patients than in the controls. CONCLUSIONS These findings demonstrate, to our knowledge for the first time, that face recognition memory in patients with Alzheimer is improved when differential outcomes are used and draw attention to the potential of this procedure as a therapeutic technique.

Minimizing sleep deprivation effects in healthy adults by differential outcomes.

Sleep deprivation reduces vigilance or arousal levels, affecting the efficiency of certain cognitive functions such as learning and memory. Here we assessed whether the differential outcomes procedure (DOP), a learning procedure that has proved useful to ameliorate episodic memory deficits, can also improve memory performance in sleep-deprived participants. Photographs were presented as sample faces. A probe face was then presented for recognition after either short or long delays. In the differential outcomes condition a unique reinforcer followed correct responses. In the non-differential outcomes condition reinforcers were provided in a random manner. The results indicated that the DOP prevented the recognition memory to decrement during the long delay in the control group, replicating previous findings. The sleep-deprived group showed DOP benefits mainly with the short delay, when working memory could be affected by low arousal. These findings confirm that the DOP can overcome impaired recognition memory due to sleep deprivation conditions.

Improving conditional discrimination learning and memory in five-year-old children: Differential outcomes effect using different types of reinforcement

Previous studies have demonstrated that discriminative learning is facilitated when a particular outcome is associated with each relation to be learned. When this training procedure is applied (the differential outcomes procedure; DOP), learning is faster and better than when the typical common outcomes procedure or nondifferential outcomes (NDO) is used. Our primary purpose in the two experiments reported here was to assess the potential advantage of DOP in 5-year-old children using three different strategies of reinforcement in which (a) children received a reinforcer following a correct choice (“ + ”), (b) children lost a reinforcer following an incorrect choice (“ − ”), or (c) children received a reinforcer following a correct choice and lost one following an incorrect choice (“ + / − ”). In Experiment 1, we evaluated the effects of the presence of DOP and different types of reinforcement on learning and memory of a symbolic delayed matching-to-sample task using secondary and primary reinforcers. Experiment 2 was similar to the previous one except that only primary reinforcers were used. The results from these experiments indicated that, in general, children learned the task faster and showed higher performance and persistence of learning whenever differential outcomes were arranged independent of whether it was differential gain, loss, or combinations. A novel finding was that they performed the task better when they lost a reinforcer following an incorrect choice (type of training “ − ”) in both experiments. A further novel finding was that the advantage of the DOP over the nondifferential outcomes training increased in a retention test.