A functional near-infrared spectroscopy study on the prefrontal correlates of cognitive offloading via a personal knowledge assistant.

The saving of previously encoded information boosts both memory for subsequent information (saving-enhanced memory; SEM) as well as cognitive performance in general (saving-enhanced performance; SEP). These findings have been replicated in a setting that involves the assistance by an intelligent software that automatically structures and saves work content in an interactive sidebar. It is assumed that beneficial effects on cognitive performance due to (automatic) saving are caused by a reduction in current workload by means of cognitive offloading. We tested this assumption by measuring neural activity in the dorsolateral prefrontal cortex (DLPFC) via functional near infrared spectroscopy (fNIRS)-once after saving and once after deleting of previously collected information that had to be recalled later-on. On a behavioral level, there was a brief benefit of saving. However, cognitive offloading became most apparent on a neural level: after saving, participants showed significantly lower activation in the right DLPFC. Also, the more participants benefited from cognitive offloading, the more they were able to re-access previously collected, saved information. Thus, fNIRS results indicated reduced mental load after saving, confirming the assumption that saving triggers cognitive offloading.

Protecting against mental impasses: Evidence of selective retrieval mitigating the impact of fixation in creative problem solving.

A common issue in creative problem solving is the unintended fixation on strongly associated, yet inappropriate solutions. In two experiments, we investigated whether lowering their accessibility by means of selective retrieval can positively affect subsequent problem-solving performance in a Compound Remote Associate test. Misleading associates were strengthened by letting participants memorize them alongside with neutral words. Half of the participants then selectively retrieved the neutral words in a cued recall test, temporarily weakening the activation level of induced fixation. In both experiments, this resulted in less impairment of subsequent performance for fixated CRA problems in early problem-solving stages (0-30 s). Additional results further revealed that participants who had engaged in prior selective retrieval perceived an increased feeling of having had immediate access to target solutions. These findings correspond to the assumption of inhibitory processes being a critical factor in both retrieval-induced forgetting and overcoming fixation in creative problem solving or preventing it from occurring in the first place. Also, they provide important insight into how strongly problem solving success is influenced by fixation.

How Disability Stereotypes Shape Memory for Personal Attributes.

Two experiments examined effects of including an information about a disability in a person description on memory about that person's traits. In Experiment 1, this information impaired correct recognition of traits of a person that had been described in correspondence to gender stereotypes. In Experiment 2, it induced false memories in accordance with stereotypes about people with disabilities. Participants' false alarms for traits belonging to the dimension of warmth increased, whereas false alarms for traits belonging to the dimension of competence decreased. Thus, activating stereotypes through a disability prime influenced what could be recognized correctly or falsely was assumed to be recognized about a person.

Suppression-induced forgetting of motor sequences.

Two experiments examined the effects of deliberately suppressing retrieval of motor sequences on their later recall, in the think/no-think paradigm (Anderson & Green, 2001). After several motor sequences had been associated with individual cues through repeated practice cycles, a subset of these sequences was retrieved in response to their respective cues (think trials), whereas other sequences were suppressed. In such no-think trials, cues were shown but participants were instructed to withhold the associated motor response and to suppress its recollection. We found that suppressing retrieval impaired later memory performance for the suppressed sequences in comparison to items that were not cued at all after their initial training (baseline sequences). Suppression impaired later sequence recall and sequence speed although in different ways depending on the training level: with higher initial training of sequences (Experiment 1), suppression impaired reaction time, but not recall accuracy; with lower initial training (Experiment 2), suppression reduced recall accuracy. Reaction time analyses revealed a consistent slowing of movement execution for suppressed sequences. These findings show that inhibitory control processes engaged during retrieval suppression can influence memory representations of motor actions, by not only reducing their accessibility but also by affecting their execution, once retrieved.

Electrophysiological correlates of saving-enhanced memory: Exploring similarities to list-method directed forgetting.

People regularly outsource parts of their memory onto external memory stores like computers or smartphones. Such cognitive offloading can enhance subsequent memory performance, as referred to the saving-enhanced memory effect (Storm & Stone, 2015). The cognitive mechanisms of this effect are not clear to date, however similarities to list-method directed forgetting (LMDF) have been stated. Here, we examined in 52 participants the electrophysiological (EEG) correlates of the saving-enhanced memory effect and compared our results to earlier LMDF findings (Hanslmayr et al., 2012). For this purpose, EEG alpha power and alpha phase synchrony during the encoding of two word lists were compared as a function of saving or no-saving. We hypothesised that if saving-enhanced memory was related to LMDF, saving in comparison to no-saving between lists should reduce alpha power and alpha phase synchrony during List 2 encoding, two effects that have been related to List 2 encoding benefits and List 1 inhibition in the earlier LMDF work. The results showed no statistically significant saving-enhanced memory effect and no significant effects in EEG alpha power or alpha phase synchrony. Possible explanations for and implications of these non-significant findings are discussed.

Selective directed forgetting of motor sequences.

We examined selective directed forgetting in motor memory using a new variant of a three-list approach, to distinguish between accounts of directed forgetting. Participants consecutively studied three lists (L1, L2, and L3) of four sequential four-finger movements each. After studying L2, participants in the forget group were instructed to selectively forget the just studied four items of L2 but to retain the previously studied four items of L1, whereas the remember group did not receive any forget instruction for L2 but was encouraged to retain the items of both lists. In addition, we switched (switch groups) or repeated the items-enacting hand (no-switch groups) between L2 and L3 for a manipulation of post-forget-cue material competition for L2. A final memory test assessed recall performance for all three lists. Selective directed forgetting (lower L2 recall in the forget group as compared to the remember group) only occurred if the same hand was used for L2 and L3 (high interference between L2 and L3 encoding) whereas no selective directed forgetting occurred if the hand switched between L2 and L3 (low interference between L2 and L3 encoding). These results suggest that an inhibitory mechanism caused (selective) directed-forgetting costs that was triggered when items studied after the forget instruction had the potential to interfere with already stored items (i.e. were to be enacted by the same hand). When subsequently studied items pertained to the other hand no directed-forgetting costs occurred.

Context-Dependent Memory of Motor Sequences.

To examine influences of context changes between encoding and retrieval of motor sequences, we varied a number of encoding and retrieval features in a two lists approach. Participants consecutively learned two sets of three-finger movements at two different computer working places, all enacted with fingers of the right hand. We varied keyboard and display orientation, stimuli, background color, response keys, position of the hand, and the used PC between the two sets. A final free recall test comprised either the same context features as present during study of the first item set or the ones present during study of the second item set or novel test context features. Results showed significant differences in overall recall performance between test conditions, indicating that context features of study episodes guided retrieval of motor sequences. In addition, the number of recalled items varied as a function of output position. Test context elements comprising context features of the first item set study episode were associated with initially lower but subsequently nearby stable recall performance, whereas test features comprising context elements of the second item set study episode were associated with initially higher and subsequently decreasing recall performance. This implies that a context reinstatement for list-1 items during the test phase does not immediately enhance accessibility of those items. However, access is subsequently facilitated over the course of retrieval attempts.

Disrupted memory inhibition in dementia of Alzheimer's type.

Cognitive inhibition has been suggested to deteriorate in Alzheimer's disease. While numerous studies with different experimental paradigms found evidence on impaired inhibition in attention and memory, evidence in favour of intact memory inhibition has been reported with regard to the phenomenon of retrieval-induced forgetting (Moulin et al., 2002). Here, we adapted the previously used paradigm in order to reduce the contribution of non-inhibitory processes and examined whether retrieval-induced forgetting could still be observed in a sample of participants with diagnosed Alzheimer's disease. In contrast to the previous finding, we found that retrieval-induced forgetting only occurred in an age-matched control group. These results suggest that inhibitory deficits in Alzheimer's disease also generalize to memory inhibition that resolves interference occurring during retrieval, whereas effects of retrieval-induced forgetting may still occur when non-inhibitory causes, such as, blocking by previously retrieved content, are not precluded.

Specifying the mechanisms behind benefits of saving-enhanced memory.

By saving information on external memory stores, we can offload temporarily irrelevant memories, we believe to be important in the future. The external saving of encoded items enhances subsequent memory performance for new information (Storm and Stone in Psychol Sci 26(2):182-188, 2015). Across three experiments, we replicated and specified this saving-enhanced memory effect. In Experiment 1, we replicated the benefits of saving and showed that they are robust against changes in instructions. In Experiment 2, we extended the saving-enhanced memory effect to motor material and more important, found evidence for better encoding after saving. In Experiment 3, a cost effect for saved verbal material was present, indicating that externally saving information can reduce the accessibility for this information afterwards. These findings suggest that at least two factors contribute to benefits of saving, better encoding and reduced interference at recall. Hereby, similarities of saving-enhanced memory to effects of the list-method directed forgetting phenomenon and useful implications for our daily information management are provided.

EEG beta power increase indicates inhibition in motor memory.

Beta power increase has been suggested to be an electrophysiological marker of response inhibition during voluntary action stopping. We examined whether beta power increase accompanies inhibition in human motor memory, focusing the phenomenon of retrieval-induced forgetting that has been assumed to be the consequence of inhibition in memory. Whereas most studies on this effect comprise word materials, a variant of the retrieval-induced-forgetting paradigm exists for examining motor memory. In the present study, we recorded scalp EEG during this motor-specific variant and examined EEG oscillatory correlates of retrieval-induced slowing of motor actions. Here, forgetting occurred in the form of significant slowing when executing motor sequences in a final recall test. Participants first learned to associate memory cues to sequential finger movements, half of which were performed with the left hand and half with the right hand. They then selectively retrieval-practiced half of the items of one hand before finally memory for all items was tested. On a behavioral level, selective retrieval practice induced slower execution of the non-retrieved items of the retrieval-practiced hand in a final memory test. On a physiological level, this retrieval-induced-slowing effect was predicted by an increase of EEG beta power during retrieval practice. The results suggest that motor retrieval-induced forgetting is a consequence of inhibition in human memory.

From A to Z? Retrieval-induced forgetting of non-verbal information indicates how writing systems can shape memory organisation.

We investigated retrieval-induced forgetting of motor sequences in samples of Chinese participants. Retrieval-induced forgetting occurs when selective retrieval of a subset of information stored in memory causes forgetting for the non-retrieved rest. This phenomenon critically depends on the organised storage of separate categories of memory representations. In studies with participants from a Western culture (Germany), a categorization in left- and right-hand movements previously had been supported by letter stimuli based on a spatial mental representation of the Roman alphabet. The same assignment of letters from the beginning or end of the alphabet to motor sequences performed either with the left- or the right-hand did not entail retrieval-induced forgetting in the present study, however (Experiment 1). In Experiment 2, visual features of displaying to-be-learned sequences additionally supported a distinction into left and right. In Experiment 3, learning trials provided verbal category labels. The occurrence of retrieval-induced forgetting in the latter two experiments suggests language-dependent organisation of non-verbal items in memory.

Retrieval-based skill learning: testing promotes the acquisition of scientific experimentation skills.

We investigated whether retrieval-based learning can facilitate the acquisition of cognitive skills, focusing on the control-of-variables strategy. This core scientific experimentation skill is regularly taught in science education classes because understanding it is essential for understanding experimental investigations in science. In the present study, participants initially read a text explaining the control-of-variables strategy. We compared the effects of subsequent retrieval practice and restudy of the text in performing a transfer test requiring the application of the control-of-variables strategy by judging the validity of a number of experimental designs. In addition, recall of the initially studied text was assessed as well. Repeated retrieval practice in combination with restudy opportunities resulted in better performance in both the transfer test and the recall test as compared to mere restudy or a single study opportunity. These findings demonstrate that retrieval practice is a useful tool for promoting deep conceptual learning.

Directed forgetting in problem solving.

In two experiments, we investigated intentional forgetting of problem-solving routines by adapting the list method of directed forgetting. In Experiment 1, participants practiced solving water-jar problems (Luchins, 1942). After working on a first series of problems that all could be solved by the same formula, one group of participants was instructed to forget the so-far presented items because these, allegedly, had only served as a warm-up, whereas another group did not receive a forget instruction. After practicing a different routine in a second series of problems, participants solved test problems that either could be solved by the formula previously practiced in the first or in the second series of problems. All test problems alternatively could be solved by a more direct formula. The forget instruction significantly reduced the number of test problems solved by the formula of the first series of practice problems. In Experiment 2, participants subsequently practiced two solution formulas in two series of to-be-solved anagrams. Here, a forget instruction regarding the first series of practice anagrams reduced solution speed for test anagrams that had to be solved by the same formula as the to-be-forgotten practice anagrams. Thus, in both experiments, participants relied less on a practiced routine after they had been instructed to intentionally forget the episode of acquiring that routine.

Saving-enhanced performance: saving items after study boosts performance in subsequent cognitively demanding tasks.

By saving and storing information, we use digital devices as our external memory stores, being able to offload and temporarily forget saved contents. Storm and Stone [2015. Saving-enhanced memory: The benefits of saving on the learning and remembering of new information. Psychological Science, 26(2), 182-188] showed that such memory offloading can be beneficial for subsequent memory performance. Saving already encoded items enhanced recall of items encoded after saving. In the present study, we did not only replicate saving-enhanced memory but found saving-enhanced performance for unrelated cognitively demanding tasks. Participants solved more modular arithmetic problems when they were able to offload a previously studied word list, compared to trials without the possibility to offload. Thus, saving of recently encoded items entailed a general benefit on subsequent cognitive performance, beyond encoding and retrieving word lists. We assume that offloading frees participants from the need to maintain offloaded items. Gained resources can then be used for subsequent tasks with high cognitive demands. In a nutshell, memory offloading can help to reduce the amount of information that has to be processed at a given time, efficiently delegating our limited cognitive resources to the most relevant tasks at hand while currently irrelevant information are safely stored outside our own memory.

Testing enhances motor practice.

We investigated how retrieval of a set of newly learned motor sequences influences subsequent learning of another set of motor sequences. In four experiments, retrieval reduced an acceleration of movement execution over subsequent study trials. This relative slowing-down was associated with better recall performance in a final memory test. Explicit retrievability of motor sequences benefited from longer study-trial response times (RTs), suggesting that retrieval caused more attentive encoding. The use of motor sequences requiring overt action during encoding allowed for this demonstration of a twofold forward effect of testing on encoding quality and on recall. Experiment 1 adopted a paradigm used in previous studies with verbal materials. Experiment 2 changed the test format to be less susceptible to interference. Experiments 3 and 4 additionally switched from a between-participants design to a within-participants design. These modifications did not affect the occurrence of the twofold forward effect of testing but enabled detecting a correlation between recall and study-trial performance that had been precluded by the strongly interference-dependent test format of the original paradigm. Our findings demonstrate an immediate learning benefit of testing. It enhances encoding in subsequent study trials.

Promoter haplotypes of the corticotropin-releasing hormone encoding gene modulate the physiological stress response in vitro and in vivo.

The corticotropin-releasing hormone (CRH) is a neuropeptide mediating stress responses. CRH exerts effects via the hypothalamus pituitary adrenal axis as well as immediate effects on the sympathetic-adrenal-medullary system. Genetic variants of the CRH promoter were previously found to be associated with altered CRH promoter activity and physiological reactions. Functional characterization of three CRH promoter haplotypes have been performed in vitro using a reporter gene assay under different stimulation conditions. Furthermore, 232 healthy subjects were genotyped and the influence of CRH haplotypes on basal parameters such as post-awakening cortisol and blood pressure as well as on stress reactivity measured after socially evaluated cold pressor test (SeCPT) was investigated. In vitro, CRH haplotype 2 showed the highest promoter activity under baseline conditions and after forskolin stimulation compared with other haplotypes. Forskolin treatment resulted in a two fold increase of haplotype 2 promoter activity compared with the baseline condition. Cell line-dependent promoter activation was found after hydrocortisone treatment. In vivo, CRH haplotype 2 carriers showed significant higher baseline blood pressure (p = .002) and blood pressure after SeCPT (p < .001), but did not differ in cortisol levels. This study provides converging evidence for the importance of CRH promoter variants on physiological stress response parameters.

Feedback increases benefits but not costs of retrieval practice: Retrieval-induced forgetting is strength independent.

We examined how the provision of feedback affected two separate effects of retrieval practice: strengthening of practiced information and forgetting of related, unpracticed information. Feedback substantially increased recall of retrieval-practiced items. This unsurprising result shows once again that restudy opportunities boost the benefits of testing. In contrast, retrieval-induced forgetting was unaffected by the manipulation and occurred in equal size with or without feedback. These findings demonstrate strength independence of retrieval-induced forgetting and thus support a theoretical account assuming that an inhibitory mechanism causes retrieval-induced forgetting. According to this theory, inhibition resolves competition that arises during retrieval attempts but is unrelated to the consequences of retrieval practice concerning practiced items. The present results match these assumptions and contradict the theoretical alternative that blocking by strengthened information might explain retrieval-induced forgetting. We discuss our findings against the background of previous studies.

Long-Term Memory Updating: The Reset-of-Encoding Hypothesis in List-Method Directed Forgetting.

People's memory for new information can be enhanced by cuing them to forget older information, as is shown in list-method directed forgetting (LMDF). In this task, people are cued to forget a previously studied list of items (list 1) and to learn a new list of items (list 2) instead. Such cuing typically enhances memory for the list 2 items and reduces memory for the list 1 items, which reflects effective long-term memory updating. This review focuses on the reset-of-encoding (ROE) hypothesis as a theoretical explanation of the list 2 enhancement effect in LMDF. The ROE hypothesis is based on the finding that encoding efficacy typically decreases with number of encoded items and assumes that providing a forget cue after study of some items (e.g., list 1) resets the encoding process and makes encoding of subsequent items (e.g., early list 2 items) as effective as encoding of previously studied (e.g., early list 1) items. The review provides an overview of current evidence for the ROE hypothesis. The evidence arose from recent behavioral, neuroscientific, and modeling studies that examined LMDF on both an item and a list level basis. The findings support the view that ROE plays a critical role for the list 2 enhancement effect in LMDF. Alternative explanations of the effect and the generalizability of ROE to other experimental tasks are discussed.

Corrigendum: Inhibitory Control in Speech Comprehension among Dai-Han Bilingual Children.

[This corrects the article on p. 1391 in vol. 8, PMID: 28861022.].

Inhibitory Control in Speech Comprehension among Dai-Han Bilingual Children.

We aimed to investigate differences in inhibitory control ability between proficient and non-proficient Dai-Han bilinguals. Two experiments used a combined stimulus-stimulus and stimulus-response compatibility paradigm for this purpose. Participants were Dai-Han bilingual primary-school students selected from a Dai-speaking town in Yunnan province, China. In Dai language interference condition, participants were asked to complete a picture category task. Results showed that the effect of attentional control for non-proficient bilinguals (NPBs) was significantly greater than that for proficient bilinguals (PBs), while the effect of response inhibition was not. This implied that a difference in inhibitory control between PBs and NPBs appeared at the attention control stage when interference by the Dai lexicon emerged. In Han language interference condition, however, participants were also asked to complete the same task. Results showed that the effect of response inhibition for NPBs was significantly greater than that for PBs, but the effect of attentional control was not. This demonstrated that a difference in inhibitory control emerged at the response inhibition stage when interference by the Han lexicon emerged. This pattern of results is opposite to previous researches, which indicated that the difference between PBs and NPBs occurred at the response inhibition stage under first language condition, whereas at the attentional control stage under second language (L2) condition. Based on these, this study suggests that Dai-Han bilinguals showed a remarkable L2 advantage. In addition, results showed that response times (RTs) of PBs were faster than RTs of NPBs while confounding variables (e.g., intelligence, etc.) were under control. This indicates that the inhibitory control ability of the PBs is superior to that of NPBs in this study.