Maria Teresa Bajo

How Does Bilingualism Improve Executive Control? A Comparison of Active and Reactive Inhibition Mechanisms

It has been claimed that bilingualism enhances inhibitory control, but the available evidence is equivocal. The authors evaluated several possible versions of the inhibition hypothesis by comparing monolinguals and bilinguals with regard to stop signal performance, inhibition of return, and the attentional blink. These three phenomena, it can be argued, tap into different aspects of inhibition. Monolinguals and bilinguals did not differ in stop signal reaction time and thus were comparable in terms of active-inhibitory efficiency. However, bilinguals showed no facilitation from spatial cues, showed a strong inhibition of return effect, and exhibited a more pronounced attentional blink. These results suggest that bilinguals do not differ from monolinguals in terms of active inhibition but have acquired a better ability to maintain action goals and to use them to bias goal-related information. Under some circumstances, this ability may indirectly lead to more pronounced reactive inhibition of irrelevant information.

Articulatory Suppression in Language Interpretation: Working Memory Capacity, Dual Tasking and Word Knowledge.

How do interpreters manage to cope with the adverse effects of concurrent articulation while trying to comprehend the message in the source language? In Experiments 1–3, we explored three possible working memory (WM) functions that may underlie the ability to simultaneously comprehend and produce in the interpreters: WM storage capacity, coordination and word knowledge. In Experiments 1 and 2, interpreters, high span individuals and control participants performed free recall tasks under normal, articulatory suppression conditions (Experiment 1) or while performing a secondary task (Experiment 2). In Experiment 3, professional interpreters free recalled nonwords or words in their first (L1) and second language (L2). The results indicated that the ability of the interpreters to simultaneously comprehend and produce is related to word knowledge rather than to an increased WM storage capacity or to an enhanced ability to coordinate processes and tasks.

Long-term effects of chronic khat use: impaired inhibitory control

So far no studies have systematically looked into the cognitive consequences of khat use. This study compared the ability to inhibit and execute behavioral responses in adult khat users and khat-free controls, matched in terms of age, race, gender distribution, level of intelligence, alcohol and cannabis consumption. Response inhibition and response execution were measured by a stop-signal paradigm. Results show that users and non-users are comparable in terms of response execution but users need significantly more time to inhibit responses to stop signals than non-users.

Phonetic and semantic activation during picture and word naming

Abstract The present research examines whether phonetic and semantic priming can be obtained for pictorial material, and more importantly, if these effects can be obtained across modalities (picture primes—word targets and word primes—picture targets). In the experiment, pictures and words were used as primes and targets in a primed naming task. Cross-modality priming for both the phonetic and semantic dimension was obtained. Results are discussed as consistent with models that propose common semantic and phonetic representations for pictures and words.

Lexical and Semantic Search in Cued Recall, Fragment Completion, Perceptual Identification, and Recognition

Search processes in word-stem cued recall, fragment completion, perceptual identification, and recognition are contrasted. These retention tests involve letters as cues, but the lexical characteristics of these cues vary considerably. In word-stem cued recall, ending letters are presented as recall cues for studied targets (e.g., ONEY as a cue for HONEY). In fragment completion, the test cues consist of letters and spaces (e.g., HO__Y); in perceptual identification, they consist of letter features that survive the mask; and in recognition, they consist of all the letters of the studied word (e.g., HONEY). These differences in retention tests and lexical characteristics were evaluated by manipulating three variables with known effects in cued recall: (a) the presence of study context words emphasizing lexical information, (b) lexical set size corresponding to the number of words that fit the letter cue, and (c) meaning set size corresponding to the number of meaningful associates linked to the studied targets. The results indicated that (a) the presence of study contexts emphasizing lexical information reduced accuracy and response time equally in all tasks, (b) larger lexical set sizes reduced accuracy and response time in all tasks except recognition, and (c) larger meaning set size reduced accuracy in cued recall but not in the other tasks. Lexical search appears to be a significant component process in word-stem cued recall, fragment completion, and identification. Searching through meaning-related concepts encoded during study is a significant component process only in cued recall.

Cognitive substrates in semantic memory of formal thought disorder in schizophrenia

Formal thought disorder (FTD) has been associated with abnormalities in the semantic memory system. However, it is still unclear whether these abnormalities are related to the organization of the semantic system, or to the automatic spread of activation-inhibition in semantic networks. In this paper these alternative proposals are examined. Schizophrenic patients and healthy matched controls were given two semantic memory tasks. In the first task, participants were required to judge the similarity between pairs of natural concepts. These ratings are assumed to reflect the underlying knowledge organization. In the second task, participants were required to name pictures that were preceded by related or unrelated word primes. Interference is typically observed when pictures are preceded by semantically related primes, and it is explained as due to inhibitory processes from the word prime to the related picture target. The results showed that the semantic structures derived from the similarity ratings were similar for patients with and without FTD and for control participants. However, results from the picture-naming task indicated that both non-FTD and control participants showed the normal interference/inhibition effects from the related prime words, whereas the patients with FTD showed similar performance for pictures preceded by related words than for pictures preceded by unrelated words. These findings support the hypothesis that abnormalities in inhibitory processes in semantic memory underlie FTD.

Prior knowledge and cued recall: category size and dominance.

Previous work indicates that our ability to recall a recently experienced word is reduced by the number of related concepts that it activates in permanent memory. The purpose of this research was to evaluate the possibility that dominance of primary associates, and not category size, is responsible for this observation. The results of three experiments involving manipulations of target and cue set size, as well as meaning and rhyme, indicate that category size effects are independent of dominance. In fact, the advantage of smaller categories and fewer activated items is substantially reduced for words having very dominant primary associates. The findings are discussed in relation to the Sensory-Semantic model.

Inhibitory effects of thought substitution in the think/no-think task: Evidence from independent cues

When people try not to think about a certain item, they can accomplish this goal by using a thought substitution strategy and think about something else. Research conducted with the think/no-think (TNT) paradigm indicates that such strategy leads subsequently to forgetting the information participants tried not to think about. The present study pursued two goals. First, it investigated the mechanism of forgetting due to thought substitution, contrasting the hypothesis by which forgetting is due to blocking caused by substitutes with the hypothesis that forgetting is due to inhibition (using an independent cue methodology). Second, a boundary condition for forgetting due to thought substitution was examined by creating conditions under which the generation of appropriate substitutes would be impaired. In two experiments, participants completed a TNT task under thought substitution instructions in which either words or pseudo-words were used as original cues and memory was assessed with original and independent cues. The results revealed forgetting in both original and independent cue tests, supporting the inhibitory account of thought substitution, but only when cues were words, and not when they were non-words, pointing to the ineffectiveness of a thought substitution strategy when original cues lack semantic content.

Strategic associative priming in the lexical decision task

Two experiments explore the nature of prelexical expectancy processes in the lexical decision task. The strength of the prime-target relationship and the size of the associative set defined by the prime were manipulated in both experiments. In Experiment 1, the proportion of strong relative to weak primes induced subjects to include strong and weak candidate words in their expectancy set, whereas in Experiment 2 that proportion attempted to induce subjects to include mainly strongly related words. Results showed that priming depended on whether the primes were included in the set. Thus, in Experiment 1 facilitation was obtained for both strong and weak primes, whereas in Experiment 2 the facilitation of weak primes depended on the size of the associative set defined by the prime. Results are discussed within a theoretical framework that includes prelexical expectancy processes in the lexical decision task.

Chronic and recreational use of cocaine is associated with a vulnerability to semantic interference

RationaleLanguage production requires that speakers effectively recruit inhibitory control to successfully produce speech. The use of cocaine is associated with impairments in cognitive control processes in the non-verbal domain, but the impact of chronic and recreational use of cocaine on these processes during language production remains undetermined.ObjectivesThis study aims to observe the possible impairment of inhibitory control in language production among chronic and recreational cocaine polydrug users.MethodTwo experiments were carried out on chronic (experiment 1) and recreational (experiment 2) cocaine polydrug users performing a blocked-cycled naming task, yielding an index of semantic interference. Participants were matched for sex, age, and intelligence (Raven’s Standard Progressive Matrices) with cocaine-free controls, and their performance was compared on the blocked-cycled naming task.ResultsChronic and recreational users showed significantly larger semantic interference effects than cocaine-free controls, thereby indicating a deficit in the ability to inhibit interfering information.ConclusionEvidence indicates a relationship between the consumption of cocaine, even at recreational levels, and the inhibitory processes that suppress the overactive lexical representations in the semantic context. This deficit may be critical in adapting and responding to many real-life situations where an efficient self-monitoring system is necessary for the prevention of errors.