Can we learn from errors? Retrieval facilitates the correction of false memories for pragmatic inferences.

Errorful learning suggests that, when perfect learning has not yet been attained, errors can enhance future learning if followed by corrective feedback. Research on memory updating has shown that after retrieval, memory becomes more malleable and prone to change. Thus, retrieval of a wrong answer might provide a good context for the incorporation of feedback. Here, we tested this hypothesis using sentences including pragmatic sentence implications, commonly used for the study of false memories. Across two experiments with young adults, we hypothesized that corrective feedback would be more efficient at reducing false memories if provided immediately after retrieval, when memory is more malleable than after being exposed to the material. Participants' memory was assessed as a function of the type of learning task (Experiment 1: retrieval vs. restudy; and Experiment 2: active vs. passive recognition); and whether participants received corrective feedback or not. In both experiments, we observed that retrieval not only improved correct recall (replicating the testing effect) but also promoted the correction of false memories. Notably, corrective feedback was more effective when given after errors that were committed during retrieval rather than after restudy (Experiment 1) or after passive recognition (Experiment 2). Our results suggest that the benefits of retrieval go beyond the testing effect since it also facilitates false memories correction. Retrieval seems to enhance memory malleability, thus improving the incorporation of feedback, compared to the mere presentation of the information. Our results support the use of learning strategies that engage in active and explicit retrieval because, even if the retrieved information is wrong-when immediate feedback is provided-memory updating is promoted and errors are more likely to be corrected.

Baseline capacities and motivation in executive control training of healthy older adults.

OBJECTIVES: Normal aging involves progressive prefrontal declines and impairments in executive control. This study aimed to examine the efficacy of an executive-control training focusing on working memory and inhibition, in healthy older adults, and to explore the role of individual differences in baseline capacities and motivation in explaining training gains. METHODS: Forty-four healthy older adults were randomly assigned to an experimental (training executive control) or active control group (training processing speed). Participants completed six online training sessions distributed across two weeks. Transfer effects to working memory (Operation Span test), response inhibition (Stop-Signal test), processing speed (Pattern Comparison) and reasoning (Raven's Advanced Progressive Matrices and Cattell Culture Fair test) were evaluated. Furthermore, we explored individual differences in baseline capacities and assessed motivation during and after the intervention. RESULTS: The experimental group, but not the active control, showed significant transfer to response inhibition. Moreover, a general compensation effect was found: older adults with lower baseline capacities achieved higher levels of training improvement. Motivation was not related to training performance. CONCLUSION: Our results encourage the use of executive control training to improve cognitive functions, reveal the importance of individual differences in training-related gains, and provide further support for cognitive plasticity during healthy aging.

Imagination Reduces False Memories for Everyday Action Sentences: Evidence From Pragmatic Inferences.

Human memory can be unreliable, and when reading a sentence with a pragmatic implication, such as "the karate champion hit the cinder block," people often falsely remember that the karate champion "broke" the cinder block. Yet, research has shown that encoding instructions affect the false memories we form. On the one hand, instructing participants to imagine themselves manipulating the to-be-recalled items increase false memories (imagination inflation effect). But on the other hand, instructions to imagine have reduced false memories in the DRM paradigm (imagination facilitation effect). Here, we explored the effect of imaginal encoding with pragmatic inferences, a way to study false memories for information about everyday actions. Across two experiments, we manipulated imaginal encoding through the instructions given to participants and the after-item filler task (none vs. math operations). In Experiment 1, participants were either assigned to the encoding condition of imagine+no filler; pay attention+math; or memorize+math. In Experiment 2, the encoding instructions (imagine vs. memorize) and the filler task (none vs. math) were compared across four separate conditions. Results from the two experiments showed that imagination instructions lead to better memory, by showing a higher proportion of correct responses and better performance in a memory benefit index. Similarly, a significant reduction of false memories was observed across both experiments, even though a complementary Bayesian analysis only supported this conclusion for Experiment 1. The findings show that imaginal encoding improves memory, suggesting the engagement of a distinctiveness heuristic and source-monitoring process.

Recognizing emotions in bodies: Vagus nerve stimulation enhances recognition of anger while impairing sadness.

According to the Polyvagal theory, the vagus nerve is the key phylogenetic substrate that supports efficient emotion recognition for promoting safety and survival. Previous studies showed that the vagus nerve affects people's ability to recognize emotions based on eye regions and whole facial images, but not static bodies. The purpose of this study was to verify whether the previously suggested causal link between vagal activity and emotion recognition can be generalized to situations in which emotions must be inferred from images of whole moving bodies. We employed transcutaneous vagus nerve stimulation (tVNS), a noninvasive brain stimulation technique that stimulates the vagus nerve by a mild electrical stimulation to the auricular branch of the vagus, located in the anterior protuberance of the outer ear. In two sessions, participants received active or sham tVNS before and while performing three emotion recognition tasks, aimed at indexing their ability to recognize emotions from static or moving bodily expressions by actors. Active tVNS, compared to sham stimulation, enhanced the recognition of anger but reduced the ability to recognize sadness, regardless of the type of stimulus (static vs. moving). Convergent with the idea of hierarchical involvement of the vagus in establishing safety, as put forward by the Polyvagal theory, we argue that our findings may be explained by vagus-evoked differential adjustment strategies to emotional expressions. Taken together, our findings fit with an evolutionary perspective on the vagus nerve and its involvement in emotion recognition for the benefit of survival.

The Effect of Transcutaneous Auricular Vagal Nerve Stimulation (taVNS) on P3 Event-Related Potentials during a Bayesian Oddball Task.

Transcutaneous auricular Vagal Nerve Stimulation (taVNS) is a non-invasive brain stimulation technique associated with possible modulation of norepinephrinergic (NE) activity. NE is suspected to contribute to generation of the P3 event-related potential. Recent evidence has produced equivocal evidence whether taVNS influences the P3 in healthy individuals during oddball tasks. We examined the effect of taVNS on P3 amplitudes using a novel visual Bayesian oddball task, which presented 200 sequences of three stimuli. The three consecutive stimuli in each sequence are labelled Draw 1, Draw 2 and Draw 3. In total, 47 Subjects completed this visual Bayesian oddball task under randomised sham and active taVNS stimulation in parallel with an electroencephalographic (EEG) recording. We conducted exploratory analyses of the effect of taVNS on P3 amplitudes separately for Draws. We found typical oddball effects on P3 amplitudes at Draws 1 and 2, but not Draw 3. At Draw 2, the oddball effect was enhanced during active compared to sham taVNS stimulation. These data provide evidence that taVNS influences parietal P3 amplitudes under specific circumstances. Only P3 amplitudes at Draw 2 were affected, which may relate to closure of Bayesian inference after Draw 2. Our findings seemingly support previously reported links between taVNS and the NE system.

Transcutaneous vagus nerve stimulation modulates attentional resource deployment towards social cues.

Transcutaneous vagus nerve stimulation (tVNS) has been shown to promote inferences of emotional states based on eye-related information provided by facial expressions of emotions. Eye gaze direction can influence the allocation of attentional sources when processing facial emotional stimuli. Here we sought for further evidence indicating whether tVNS effects would be specific to emotional expressions or to gaze - both socially relevant stimuli - and whether they reflect the enhancement of attention. In two separate sessions receiving either active or sham tVNS, forty-three healthy young volunteers completed a Rapid Serial Visual Presentation task in which participants identified the gender of a target face (T1) with direct (salient social cue) or averted gaze (subtler social cue) with different emotional expressions or a neutral expression, and then judged the orientation of a landscape (T2) that appeared at different temporal lags after T1. Active tVNS, compared to sham stimulation, enhanced conditional T2 accuracy for both neutral and emotional faces and independently of the temporal lag, but only when gaze was directed at the participant. This suggests that tVNS modulates attention to a direct gaze (salient social cue) irrespective of the expressed emotion. We interpret that the effects of tVNS seem to reflect enhanced perception of gaze direction, which in turn attracts attention, making the observer more sensitive and increasing the impact of the socially relevant facial cue. We conclude that tVNS is a promising technique for enhancing social information processing in healthy humans.

Vagal signaling and the somatic marker hypothesis: The effect of transcutaneous vagal nerve stimulation on delay discounting is modulated by positive mood.

Controlling impulsivity and delaying gratifications are key features of effective self-control. Delay Discounting (DD) indexes the ability to delay rewards and previous research has shown that discounting is influenced by affective states such as mood. According to the Somatic Marker Hypothesis (SMH), afferent somatic signals, such as mood, are carried by the vagus and can influence decision making. In the current study, we employed transcutaneous vagus nerve stimulation (tVNS), a novel non-invasive brain stimulation technique that stimulates the auricular branch of the afferent vagus nerve (located in the outer ear), to assess its effects on decision impulsivity, while taking into account individuals' mood and resting-state HRV as a possible confounding factor. Employing a within-subjects cross-over design, 94 participants received active or sham tVNS while performing delay discounting in two separate sessions. As compared to sham, active tVNS increased discounting, but only for individuals reporting lower positive mood, regardless of the level of negative mood reported. We evidence that the effect of tVNS on reward discounting depends on the level of positive mood. This result suggests that positive mood state might be a proxy of task-relevant arousal, likely influencing the effectiveness of afferent vagal stimulation on self-control processes, as temporal discounting.

Theta oscillations show impaired interference detection in older adults during selective memory retrieval.

Seemingly effortless tasks, such as recognizing faces and retrieving names, become harder as we age. Such difficulties may be due to the competition generated in memory by irrelevant information that comes to mind when trying to recall a specific face or name. It is unknown, however, whether age-related struggles in retrieving these representations stem from an inability to detect competition in the first place, or from being unable to suppress competing information once interference is detected. To investigate this, we used the retrieval practice paradigm, shown to elicit memory interference, while recording electrophysiological activity in young and older adults. In two experiments, young participants showed Retrieval-Induced Forgetting (RIF), reflecting the suppression of competing information, whereas older adults did not. Neurally, mid-frontal theta power (~4-8 Hz) during the first retrieval cycle, a proxy for interference detection, increased in young compared to older adults, indicating older adults were less capable of detecting interference. Moreover, while theta power was reduced across practice cycles in younger adults, a measure of interference resolution, older adults did not show such a reduction. Thus, in contrast with younger adults, the lack of an early interference detection signal rendered older adults unable to recruit memory selection mechanisms, eliminating RIF.

Training on Working Memory and Inhibitory Control in Young Adults.

Different types of interventions have focused on trying to improve Executive Functions (EFs) due to their essential role in human cognition and behavior regulation. Although EFs are thought to be diverse, most training studies have targeted cognitive processes related to working memory (WM), and fewer have focused on training other control mechanisms, such as inhibitory control (IC). In the present study, we aimed to investigate the differential impact of training WM and IC as compared with control conditions performing non-executive control activities. Young adults were divided into two training (WM/IC) and two (active/passive) control conditions. Over six sessions, the training groups engaged in three different computer-based adaptive activities (WM or IC), whereas the active control group completed a program with low control-demanding activities that mainly involved processing speed. In addition, motivation and engagement were monitored through the training. The WM-training activities required maintenance, updating and memory search processes, while those from the IC group engaged response inhibition and interference control. All participants were pre- and post-tested in criterion tasks (n-back and Stroop), near transfer measures of WM (Operation Span) and IC (Stop-Signal). Non-trained far transfer outcome measures included an abstract reasoning test (Raven's Advanced Progressive Matrices) and a well-validated experimental task (AX-CPT) that provides indices of cognitive flexibility considering proactive/reactive control. Training results revealed that strongly motivated participants reached higher levels of training improvements. Regarding transfer effects, results showed specific patterns of near transfer effects depending on the type of training. Interestingly, it was only the IC training group that showed far transfer to reasoning. Finally, all trained participants showed a shift toward a more proactive mode of cognitive control, highlighting a general effect of training on cognitive flexibility. The present results reveal specific and general modulations of executive control mechanisms after brief training intervention targeting either WM or IC.