M. Teresa Bajo

Retrieval-Induced Forgetting and Executive Control

Retrieving information from long-term memory can lead people to forget previously irrelevant related information. Some researchers have proposed that this retrieval-induced forgetting (RIF) effect is mediated by inhibitory executive-control mechanisms recruited to overcome interference. We assessed whether inhibition in RTF depends on executive processes. The RIF effect observed in a standard retrieval-practice condition was compared to that observed in two different conditions in which participants had to perform two concurrent updating tasks that demanded executive attention. Whereas the usual RIF effect was observed when retrieval practice was performed singly, no evidence of forgetting was found in the dual-task conditions. Results strongly suggest that inhibition involved in RIF is the result of executive-control processes.

Retrieval-induced forgetting in recall and recognition of thematically related and unrelated sentences

In three experiments, we assessed the effects of type of relation and memory test on retrieval-induced forgetting of facts. In Experiments 1 and 2, eight sets of four shared-subject sentences were presented for study. They were constructed so that half were thematically related and half were unrelated. A retrieval practice phase required participants to recall a subset of the studied sentences. In the final test, the participants were prompted to recall all the sentences (character cued in Experiment 1 and character plus stem cued in Experiment 2). The results showed that the retrieval- induced forgetting (RIF) effect was similar for thematically related and unrelated sentences, indicating that the presence of episodic relations among the sentences was sufficient to produce the effect. In Experiment 3, a recognition task was introduced and the RIF effect emerged in accuracy as well as in latency measures. The presence of this effect with item-specific cues is difficult to accommodate for noninhibitory theories of retrieval.

Inhibitory processes in memory are impaired in schizophrenia: evidence from retrieval induced forgetting

Schizophrenic patients are known to exhibit inhibitory impairments in response suppression and selective attention. However, the impairment of inhibitory control in memory retrieval has not clearly been documented. In two experiments, we investigate inhibition in memory retrieval by using the retrieval practice procedure. In Expt 1, a cued recall final test was used. Consistent with previous research, we found similar retrieval-induced forgetting (RIF) effects in schizophrenic patients and in controls. However, these effects could be the result of interference/blocking or the results of inhibition. In order to reduce the influence of blocking in Expt 2, we used a recognition test. We found that RIF was reduced in patients, compared to healthy controls. The elimination of RIF effect in patients, when the influence of blocking is reduced, indicates that inhibitory processes in memory are altered in schizophrenia. Result suggest that schizophrenic patients suffer from critical impairments in inhibitory processes involved in memory retrieval, similar to the inhibitory deficits found in other cognitive domains.

Dual mechanisms of cognitive control in bilinguals and monolinguals

Growing evidence shows that executive functioning benefits from bilingual experience. However, the nature of the mechanisms underlying this advantage remains to be clarified. Whereas some have put forward single process accounts to explain the superior performance of bilinguals relative to monolinguals in executive control tasks, recent findings have been interpreted by considering the dynamic combination of monitoring and inhibitory processes to overcome interference from distractor information. In the present study we explored this idea by comparing monolinguals and highly proficient bilinguals in the AX-CPT. This task requires individuals to adjust proactive (monitoring) and reactive (inhibition) control to achieve efficient performance. We also examined the extent to which a well-known index of inhibitory capacity, the stop-signal reaction time, predicts accuracy in the AX-CPT. Results showed that bilinguals outperformed monolinguals in the experimental condition where higher requirement of proactive-reactive control adjustment was required. Interestingly, the inhibition index predicted errors in this condition only in the sample of bilinguals. These findings suggest that a better understanding of the cognitive benefits of bilingualism may require consideration of how bilinguals adjust different executive control mechanisms to cope with interference.

Retrieval-Induced Forgetting in Perceptually Driven Memory Tests.

Recent data (T. J. Perfect, C. J. A. Moulin, M. A. Conway, & E. Perry, 2002) have suggested that retrieval-induced forgetting (RIF) depends on conceptual memory because the effect is not found in perceptually driven tasks. In 3 experiments, the authors aimed to show that the presence of RIF depends on whether the procedure induces appropriate transfer between representations and competition rather than on the nature of the final test. The authors adapted the standard paradigm to introduce lexical categories (words that shared the first 2 letters) at study and practice. Direct and indirect fragment completion tests were used at retrieval. The results showed significant RIF effects in perceptually driven tasks. Furthermore, they indicated that the presence of RIF effects depended on using adequate cuing to induce competition during the retrieval practice and on the final memory test tapping the inhibited representation.

Memory inhibition, aging and the executive deficit hypothesis

Although memory inhibition seems to underlie retrieval-induced forgetting (RIF), there is some controversy about the precise nature of this effect. Because normal RIF is observed in people with deficits in executive control (i.e., older adults), some have proposed that an automatic-like inhibitory process is responsible for the effect. On the contrary, neurocognitive and dual-task findings with young people support the view that an executive control process underlies RIF. In the present study, we address this apparent controversy by comparing young and older participants under different dual-task conditions. Our results indicate that memory inhibition in older adults also depends on executive control, which is more easily disrupted by a secondary task in older than in young adults. Thus, the fact that RIF in older adults is sometimes present is not incompatible with a decline in executive control with aging. The results also shed some light into the discussion regarding the effect of dual tasking on retrieval.

Bilingualism modulates dual mechanisms of cognitive control: Evidence from ERPs

Recent behavioral findings with the AX-Continous Performance Task (AX-CPT; Morales et al., 2013) show that bilinguals only outperform monolinguals under conditions that require the highest adjustment between monitoring (proactive) and inhibitory (reactive) control, which supports the idea that bilingualism modulates the coordination of different control mechanisms. In an ERP experiment we aimed to further investigate the role that bilingualism plays in the dynamic combination of proactive and reactive control in the AX-CPT. Our results strongly indicate that bilingualism facilitates an effective adjustment between both components of cognitive control. First, we replicated previous behavioral results. Second, ERP components indicated that bilingualism influences the conflict monitoring, response inhibition and error monitoring components of control (as indexed by the N2 and P3a elicited by the probe and the error-related negativity following incorrect responses, respectively). Thus, bilinguals exerted higher reactive control than monolinguals but only when they needed to overcome the competing cue-information. These findings join others in suggesting that a better understanding of the cognitive benefits of bilingualism may require consideration of a multi-component perspective.

Simultaneous interpretation selectively influences working memory and attentional networks

Recent research has shown that becoming an expert in a certain domain may lead to a transfer of the acquired skills to other domains requiring similar abilities. Thus, the cognitive skills acquired by professional interpreters after intensive training may also transfer to other domains. Simultaneous interpreters are known to develop high working memory capacity (e.g., Christoffels, de Groot, & Kroll, 2006; Signorelli, Haarmann, & Obler, 2012). However, little is known about transfer of other processes such us updating and some aspects of attention also involved in interpretation. In Experiment 1, we found that interpreters outperformed a control group in updating skills, as measured through a dual version of the n-back task (Jaeggi et al., 2007). In Experiment 2, use of the ANTI-V allowed us to reveal that interpreting differentially modulates the interactions between attentional networks. Thus, we found no group differences in conflict resolution, but the interaction between the alertness and orienting networks differed between interpreters and non-interpreters. Taken together, these results suggest that experience in simultaneous interpreting transfers to other domains, but this transfer seems specific to the cognitive processes more closely involved in the interpreting tasks.

Inhibition and Retrieval of Facts in Young and Older Adults

Inhibition is considered to have an important role in memory retrieval. However, many experimental results suggest that its efficiency declines with aging. In this study, the authors tested this hypothesis by using the retrieval-practice task. The retrieval-induced forgetting (RIF) observed with this paradigm is normally explained in terms of inhibition. Young (mean age 21.5 years) and older (mean age 71.6 years) adults studied sets of four shared-subject sentences. A retrieval-practice phase required participants to repeatedly recall a subset of the studied sentences. In the final test, participants were provided item-specific cues and told to recall all the studied sentences. RIF was similar for both age groups, suggesting comparable inhibitory efficiency in young and older adults.

Normative data on the n-back task for children and young adolescents.

The n-back task is a frequently used measure of working memory (WM) in cognitive neuroscience research contexts, and it has become widely adopted in other areas over the last decade. This study aimed to obtain normative data for the n-back task from a large sample of children and adolescents. To this end, a computerized verbal n-back task with three levels of WM load (1-back, 2-back, and 3-back) was administered to 3722 Spanish school children aged 7–13 years. Results showed an overall age-related increase in performance for the different levels of difficulty. This trend was less pronounced at 1-back than at 2-back when hits were considered. Gender differences were also observed, with girls outperforming boys although taking more time to respond. The theoretical implications of these results are discussed. Normative data stratified by age and gender for the three WM load levels are provided.