Toward specifying the attentional demands of recognition memory

Effects of Divided Attention at Retrieval on Conceptual Implicit Memory

This study investigated whether conceptual implicit memory is sensitive to process-specific interference at the time of retrieval. Participants performed the implicit memory test of category exemplar generation (CEG; Experiments 1 and 3), or the matched explicit memory test of category-cued recall (Experiment 2), both of which are conceptually driven memory tasks, under one of two divided attention (DA) conditions in which participants simultaneously performed a distracting task. The distracting task was either syllable judgments (dissimilar processes), or semantic judgments (similar processes) on unrelated words. Compared to full attention (FA) in which no distracting task was performed, DA had no effect on CEG priming overall, but reduced category-cued recall similarly regardless of distractor task. Analyses of distractor task performance also revealed differences between implicit and explicit memory retrieval. The evidence suggests that, whereas explicit memory retrieval requires attentional resources and is disrupted by semantic and phonological distracting tasks, conceptual implicit memory is automatic and unaffected even when distractor and memory tasks involve similar processes.

The effects of a distracting N-back task on recognition memory are reduced by negative emotional intensity

Memory performance is usually impaired when participants have to encode information while performing a concurrent task. Recent studies using recall tasks have found that emotional items are more resistant to such cognitive depletion effects than non-emotional items. However, when recognition tasks are used, the same effect is more elusive as recent recognition studies have obtained contradictory results. In two experiments, we provide evidence that negative emotional content can reliably reduce the effects of cognitive depletion on recognition memory only if stimuli with high levels of emotional intensity are used. In particular, we found that recognition performance for realistic pictures was impaired by a secondary 3-back working memory task during encoding if stimuli were emotionally neutral or had moderate levels of negative emotionality. In contrast, when negative pictures with high levels of emotional intensity were used, the detrimental effects of the secondary task were significantly attenuated.

The bilingual L2 advantage in recognition memory

To better understand the mechanisms by which bilingual proficiency impacts memory processes, two recognition memory experiments were conducted with matched monolingual and bilingual samples. In Experiment 1, monolingual speakers of English and Spanish studied high- and low-frequency words under full attention or cognitive load conditions. In Experiment 2, Spanish-English bilingual participants studied high- and low-frequency words under full-attention conditions in each language. For both monolinguals and bilinguals, low-frequency words were better recognized than high-frequency words. The central new findings were that bilingual recognition was more accurate in the less fluent language (L2) than in the more fluent language (L1) and that bilingual L2 recognition was more accurate than monolingual recognition. The bilingual L2 advantage parallels word frequency effects in recognition and is attributed to the greater episodic distinctiveness of L2 words, relative to L1 words.

When interference helps: increasing executive load to facilitate deception detection in the concealed information test

The possibility to enhance the detection efficiency of the Concealed Information Test (CIT) by increasing executive load was investigated, using an interference design. After learning and executing a mock crime scenario, subjects underwent three deception detection tests: an RT-based CIT, an RT-based CIT plus a concurrent memory task (CITMem), and an RT-based CIT plus a concurrent set-shifting task (CITShift). The concealed information effect, consisting in increased RT and lower response accuracy for probe items compared to irrelevant items, was evidenced across all three conditions. The group analyses indicated a larger difference between RTs to probe and irrelevant items in the dual-task conditions, but this difference was not translated in a significantly increased detection efficiency at an individual level. Signal detection parameters based on the comparison with a simulated innocent group showed accurate discrimination for all conditions. Overall response accuracy on the CITMem was highest and the difference between response accuracy to probes and irrelevants was smallest in this condition. Accuracy on the concurrent tasks (Mem and Shift) was high, and responses on these tasks were significantly influenced by CIT stimulus type (probes vs. irrelevants). The findings are interpreted in relation to the cognitive load/dual-task interference literature, generating important insights for research on the involvement of executive functions in deceptive behavior.

Available processing resources influence encoding-related brain activity before an event

Effective cognitive functioning not only relies on brain activity elicited by an event, but also on activity that precedes it. This has been demonstrated in a number of cognitive domains, including memory. Here, we show that brain activity that precedes the effective encoding of a word into long-term memory depends on the availability of sufficient processing resources. We recorded electrical brain activity from the scalps of healthy adult men and women while they memorized intermixed visual and auditory words for later recall. Each word was preceded by a cue that indicated the modality of the upcoming word. The degree to which processing resources were available before word onset was manipulated by asking participants to make an easy or difficult perceptual discrimination on the cue. Brain activity before word onset predicted later recall of the word, but only in the easy discrimination condition. These findings indicate that anticipatory influences on long-term memory are limited in capacity and sensitive to the degree to which attention is divided between tasks. Prestimulus activity that affects later encoding can only be engaged when the necessary cognitive resources can be allocated to the encoding process.

Attention during memory retrieval enhances future remembering

Memory retrieval is a powerful learning event that influences whether an experience will be remembered in the future. Although retrieval can succeed in the presence of distraction, dividing attention during retrieval may reduce the power of remembering as an encoding event. In the present experiments, participants studied pictures of objects under full attention and then engaged in item recognition and source memory retrieval under full or divided attention. Two days later, a second recognition and source recollection test assessed the impact of attention during initial retrieval on long-term retention. On this latter test, performance was superior for items that had been tested initially under full versus divided attention. More importantly, even when items were correctly recognized on the first test, divided attention reduced the likelihood of subsequent recognition on the second test. The same held true for source recollection. Additionally, foils presented during the first test were also less likely to be later recognized if they had been encountered initially under divided attention. These findings demonstrate that attentive retrieval is critical for learning through remembering.

The low-frequency encoding disadvantage: Word frequency affects processing demands

Low-frequency words produce more hits and fewer false alarms than high-frequency words in a recognition task. The low-frequency hit rate advantage has sometimes been attributed to processes that operate during the recognition test (e.g., L. M. Reder et al., 2000). When tasks other than recognition, such as recall, cued recall, or associative recognition, are used, the effects seem to contradict a low-frequency advantage in memory. Four experiments are presented to support the claim that in addition to the advantage of low-frequency words at retrieval, there is a low-frequency disadvantage during encoding. That is, low-frequency words require more processing resources to be encoded episodically than high-frequency words. Under encoding conditions in which processing resources are limited, low-frequency words show a larger decrement in recognition than high-frequency words. Also, studying items (pictures and words of varying frequencies) along with low-frequency words reduces performance for those stimuli.