The Role of Semantic Clustering in Optimal Memory Foraging

Recent studies of semantic memory have investigated two theories of optimal search adopted from the animal foraging literature: Lévy flights and marginal value theorem. Each theory makes different simplifying assumptions and addresses different findings in search behaviors. In this study, an experiment is conducted to test whether clustering in semantic memory may play a role in evidence for both theories. Labeled magnets and a whiteboard were used to elicit spatial representations of semantic knowledge about animals. Category recall sequences from a separate experiment were used to trace search paths over the spatial representations of animal knowledge. Results showed that spatial distances between animal names arranged on the whiteboard were correlated with inter‐response intervals (IRIs) during category recall, and distributions of both dependent measures approximated inverse power laws associated with Lévy flights. In addition, IRIs were relatively shorter when paths first entered animal clusters, and longer when they exited clusters, which is consistent with marginal value theorem. In conclusion, area‐restricted searches over clustered semantic spaces may account for two different patterns of results interpreted as supporting two different theories of optimal memory foraging.     

Reward prospect interacts with trial-by-trial preparation for potential distraction

When attending for impending visual stimuli, cognitive systems prepare to identify relevant information while ignoring irrelevant, potentially distracting input. Recent work showed that a supramodal distracter-filtering mechanism is invoked in blocked designs involving expectation of possible distracter stimuli, although this entails a cost (distraction-filtering cost) on speeded performance when distracters are expected but not presented. Here we used an arrow-flanker task to study whether an analogous cost, potentially reflecting the recruitment of a specific distraction-filtering mechanism, occurs dynamically when potential distraction is cued trial-to-trial (cued distracter-expectation cost). In order to promote the maximal utilization of cue information by participants, in some experimental conditions the cue also signalled the possibility of earning a monetary reward for fast and accurate performance. This design also allowed us to investigate the interplay between anticipation for distracters and anticipation of reward, which is known to engender attentional preparation. Only in reward contexts did participants show a cued distracter-expectation cost, which was larger with higher reward prospect and when anticipation for both distracters and reward were manipulated trial-to-trial. Thus, these results indicate that reward prospect interacts with the distracter expectation during trial-by-trial preparatory processes for potential distraction. These findings highlight how reward guides cue-driven attentional preparation.     

Collective interviewing: A transactive memory approach towards identifying signs of truthfulness

Group interviewing has been neglected in the deception literature, yet it coincides with recent collective memory research. The present experiment applied the transactive memory theory to a collective interviewing situation and explored whether signs of truthfulness emerged through measuring joint memory recall. Truth-tellers were real couples who had been in a relationship for at least one year and cohabiting. Lying pairs were friends who pretended to be in a relationship for at least one year and cohabiting. All couples were interviewed in their pairs about their ‘real’ or ‘fictitious’ relationships. It was found that truth-telling pairs posed questions to one another, provided cues to one another, handed over remembering responsibility, and finished each others’ sentences significantly more than lying pairs, supporting the idea that real couples have a transactive memory system, unlike pretending couples. Implications for a collective interview approach that considers memory within deception detection are discussed.     

Mental context reinstatement or drawing: Which better enhances children's recall of witnessed events and protects against suggestive questions?

The aim of this experiment was to examine the effectiveness of two techniques in enhancing children's recall of an event that they experienced approximately a week earlier. Younger (5–6 years) and older (8–9 years) children were interviewed about a magic show event in one of three conditions. Before recalling the event, some children were instructed to mentally reinstate the context of the event (MCR group), others were asked to draw the context of the event (DCR group), and others received no reinstatement instructions (NCR). Results showed that these instructions had no impact on children's free recall or responses to open‐ended prompts. However, reinstatement instructions impacted children's responses to suggestive questions: those in the DCR group gave more accurate responses than those in the NCR group. These findings provide preliminary support for the use of drawing as a potentially protective exercise that lessens the impact of biased questions with child witnesses.     

Influence of general and specific autobiographical recall on subsequent behavior: The case of cognitive performance

Two studies tested the impact of autobiographical recall of general versus specific academic success or failure on actual task performance. As expected, it was found that general memories of failure and specific memories of success resulted in worse performance than general memories of success and specific memories of failure. In Study 1, this performance pattern was obtained on a standard math test. In Study 2, it was replicated on a test of intellectual ability, and a mediation by fear of failure was documented. The present findings offer direct evidence that autobiographical memories of success and failure impact actual performance and also reveal the role of memory specificity in this influence.     

任务难度与老化对大脑激活的影响——以线索记忆编码为例

以汉语名词双字词对为材料,采用了两种性质、三种难度水平的线索回忆任务对12名老年被试和15名年轻被试的项目记忆编码过程进行fMRI扫描,考察在编码阶段大脑激活受任务难度变化和老化的影响。行为研究结果发现:年龄的主效应、难度的主效应以及难度与年龄交互作用均显著,即,随着任务难度的增加,老年人的成绩更加明显地低于年轻人。神经成像研究结果发现:(1)当词对的相关性降低时,大脑激活的增强主要表现为面积的增加,而当词对的频率降低时,主要表现在激活强度的增加上。(2)任务难度和大脑激活面积、强度之间均不存在对应的递增变化关系。(3)仅当词对的相关性降低时,老年人比年轻人调用了更多的额叶脑区。     

New Insights into the role of the phonological loop in task switching: evidence from three different age groups

ABSTRACT

The phonological loop plays an important role in task switching. Until now, however, it has been unclear whether it is the maintenance of the task sequence or the retrieval of the task goal that requires phonological processing. In the present study, 60 participants (20 children, 20 adolescents, 20 young adults) performed three phonological working-memory tests before they switched between two tasks in a cue-present condition (random task sequence) and in a cue-absent condition (predictable task sequence). Results revealed that better phonological and central-executive working-memory performance predicted lower switch costs. In line with age-differentiation of cognitive abilities switching was less coupled with working memory in adults compared to children and adolescents. Interestingly, however, relations were only demonstrated in the cue-present but not in the cue-absent condition, indicating that it is more the retrieval of the task goal than the maintenance of the task sequence that requires the involvement of phonological processing.     

Reliability in Dream Research: A Methodological Note

The coefficients of internal consistency and retest reliability had been rarely investigated within the methodology of dream content analysis. Analyzing a dream series of elderly, healthy persons obtained from weekly telephone interviews, the internal consistency of a series of 20 dreams and retests after 4 or 22 weeks, respectively, had been computed. The findings indicate that dream recall and dream length are quite stable, but dream characteristics such as bizarreness and emotional tone underlie large intraindividual fluctuations. In order to obtain reliable measures for these variables which will be important for correlational studies, including waking-life trait measures, one has to obtain as many dreams as possible (about 20) in a very short time period. Further research is needed to extend the present findings to diary dreams and laboratory dreams.     

Searching in the sand: Protracted video deficit in U.S. preschoolers' spatial recall using a continuous search space

Young children exhibit a video deficit for spatial recall, learning less from on-screen than in-person demonstrations. Some theoretical accounts emphasize memory constraints (e.g., insufficient retrieval cues, competition between memory representations). Such accounts imply memory representations are graded, yet video deficit studies measuring spatial recall operationalize memory retrieval as dichotomous (success or failure). The current study tested a graded-representation account using a spatial recall task with a continuous search space (i.e., sandbox) rather than discrete locations. With this more sensitive task, a protracted video deficit for spatial recall was found in children 4–5 years old (n = 51). This may be due to weaker memory representations in the screen condition, evidenced by higher variability and greater perseverative bias. In general, perseverative bias decreased with repeated trials. The discussion considers how the results support a graded-representation account, potentially explaining why children might exhibit a video deficit in some tasks but not others.

Research Highlights

• The task used a continuous search space (sandbox), making it more difficult and sensitive than spatial recall tasks used in prior video deficit research.
• Spatial recall among 4- and 5-year-old children was more variable after watching hiding events on screen via live video feed than through a window.
• Children's spatial recall from screens was more susceptible to proactive interference, evidenced by more perseverative bias in an A-not-B design.
• The results demonstrate memory representations blend experiences that accumulate over time and explain why the video deficit may be protracted for more difficult tasks.

     

Motor learning of cue-dependent pull-force changes during an isometric precision grip task

The “raspberry task” represents a precision grip task that requires continuous adjustment of grip and pull forces. During this task subjects grip a specialized grip rod and have to increase the pull force linearly while the rod is locked. The aim of this study was to determine whether an associated, initially neutral cue is able to evoke pull-force changes in the raspberry task. A standard delay paradigm was used to study cued pull-force changes during an ongoing movement resulting in unloading. Pull force and EMG activity of hand and arm muscles were recorded from 13 healthy, young subjects. The cue was associated with a complex change in motor behavior.In this task, cued force changes take place more rapidly than in protective reflex systems (in median after the second presentation of the cueing stimulus). A cued force change was detectable in two-thirds of paired trials. Although the force change is produced by a decrease of the EMG activity in several grip- and pull-force-producing muscles, the most significant effect in the majority of the subjects was an increase of the activity of the flexor carpi ulnaris muscle which antagonises corresponding pull-force-producing muscles. Cued force changes require adequately and precisely controlled activation of the muscle groups involved in the movement.