Enhanced perceived responsibility decreases metamemory but not memory accuracy in obsessive-compulsive disorder (OCD)

Mixed findings have been obtained in prior research with respect to the presence and severity of memory and metamemory deficits in obsessive-compulsive disorder (OCD). We tested the hypothesis that experimentally induced increments of subjective responsibility would lead to a disproportionately strong decline of memory confidence and enhanced response latencies in OCD while leaving memory accuracy unaffected. Twenty-eight OCD patients and 28 healthy controls were presented a computerized memory test framed with two different scenarios. In the neutral scenario, the participant was requested to imagine purchasing 15 items from a do-it-yourself store. In the recognition phase, the 15 needed items were presented along with 15 distractor items. The participant was asked to decide whether items were on his or her shopping list or not, graded by subjective confidence. In the responsibility scenario, the general experimental setup was analogous except that the participant now had to envision that he or she was a helper in a region recently struck by an earthquake, dispatched to provide 15 urgently needed goods from a nearby town. In line with prior work by our group, samples did not differ in either condition on memory accuracy in a subsequent recognition task. As hypothesized, OCD participants were less certain in their responses for the high responsibility condition than controls. Whereas patients and controls did not differ in their subjective estimates for memorized items, patients expressed stronger doubt that their earthquake mission was successful. The findings indicate that low memory confidence in OCD may only be elicited in situations where perceived responsibility is high and that patients may share higher performance standards ("good is not good enough") than controls when perceived responsibility is inflated.     

Does providing props during preparation help children to remember a novel event?

We investigated the conditions under which preparatory information presented 1 day before a novel event influenced 6-year-olds' recall 1 week later. Children were assigned to one of six experimental conditions. Three conditions involved preparatory information that described the event accurately but differed according to the presence and type of props (verbal, real props, and toy props). In two conditions, which also differed according to whether verbal information was supplemented with real props, half of the preparatory information described the event accurately, whereas the other half was thematically similar to, but inconsistent with, the event (misleading verbal and misleading props). Compared with the attentional control condition, all forms of preparation that described the event accurately increased correct recall. Preparation that included props improved photograph recognition. When half of the accurate information was replaced by misleading information, the positive benefit on recall was reduced, and when misleading props accompanied the misleading information, errors increased. The potential underlying mechanisms and implications for pediatric settings are discussed.     

The development of memory for own- and other-race faces

This study demonstrates that experience and development interact to influence the "cross-race effect." In a multination study (n=245), Caucasian children and adults of European ancestry living in the United States, Norway, or South Africa, as well as biracial (Caucasian-African American) children and adults living in the United States, were tested for recognition of Asian, African, and Caucasian faces. Regardless of national or biracial background, 8- to 10-year-olds, 12- to 14-year-olds, and adults recognized own-race faces more accurately than other-race faces, and did so to a similar extent, whereas 5- to 7-year-olds recognized all face types equally well. This same developmental pattern emerged for biracial children and adults. Thus, early meaningful exposure did not substantially alter the developmental trajectory. During young childhood, developmental influences on face processing operate on a system sufficiently plastic to preclude, under certain conditions, the cross-race effect.     

Recent Innovative Studies of Memory in Temporal Lobe Epilepsy

Investigations of patients with temporal lobe epilepsy continue to result in significant advancements in the neuroscience of human memory, as they have for over 50 years. Recent reviews describing the state of the art in the clinical neuropsychology of TLE generally have emphasized (1) lateralization of cognitive deficits and the material-specific model of memory and/or (2) the relationships among pre- and post-surgery performance on standardized measures of anterograde memory, demographic and epilepsy variables and neuroimaging, neuropathology, and neurosurgery data. As information continues to accumulate about the pattern of performance on standard laboratory memory tests and the implications of these data before and after anterior temporal lobectomy for the treatment of TLE, innovative assessment techniques also are increasingly being applied. This review focuses on English language publications that addressed selected novel topics in adult TLE memory research. These topics are: (1) remote memory; (2) accelerated forgetting or long term amnesia; and (3) lateral versus mesial temporal lobe contributions to memory.     

Enhanced spatial ability in aged dogs following dietary and behavioural enrichment

We examined the benefits of a broad spectrum antioxidant diet and enrichment comprised of physical exercise, environmental stimulants and cognitive testing, on spatial memory performance in beagle dogs. Both aged (N=48) and young (N=16) beagle dogs (Canus familiaris) were tested yearly on a three-component delayed non-match to position spatial task for three consecutive years. The results showed that young enriched animals acquired the task in fewer sessions, made fewer errors, responded slower and made fewer positional responses, compared to aged enriched animals. An analysis restricted to aged animals revealed that antioxidant administration and enrichment resulted in fewer errors, slower responses and decreased positional responses, particularly in Year 3. Finally, cohort differences emerged, which exemplify the significance of early environmental intervention. Aged dogs that were housed with other animals and exposed to an outdoor environment in early development displayed greater benefits from both interventions. These findings indicate that long-term dietary intervention and enrichment can buffer age-associated cognitive decline.     

Susceptibility to induction of long-term depression is associated with impaired memory in aged Fischer 344 rats

The current study employed aged and young male Fischer 344 rats to examine the relationship between long-term depression (LTD), age, and memory. Memory performance was measured on two tasks that are sensitive to hippocampal function; inhibitory avoidance and spatial discrimination on the Morris water maze. The slope of the extracellular excitatory postsynaptic field potential was recorded from CA3-CA1 synapses in hippocampal slices. Low frequency stimulation (LFS) induced a modest LTD only in aged animals under standard recording conditions. The decrease in synaptic transmission examined only in aged animals correlated with memory scores on the spatial task and LTD was not observed in aged animals with the highest memory scores. LTD induction was facilitated by increasing the Ca(2+)/Mg(2+) ratio of the recording medium or employing a paired-pulse stimulation paradigm. Age differences disappeared when LFS was delivered under conditions of elevated Ca(2+)/Mg(2+) in the recording medium. Using multiple induction episodes under conditions which facilitate LTD-induction, no age-related difference was observed in the maximum level of LTD. The results indicate that the increased susceptibility to LTD induction is associated with impaired memory and results from a shift in the induction process. The possible relationship between LTD and memory function is discussed.     

Opposing effects of age and reading ability on pseudoword priming

Repetition priming refers to the facilitation of stimulus processing due to prior processing of the same or similar stimulus, and is one of the most primitive ways in which experience and practice can affect performance. Previous studies have produced contradictory results regarding the stability of repetition priming across development. Drawing on models of word priming that suggest decreased priming with increased reading ability, the present experiment investigated the possibility that null effects of age in priming are due to opposing effects of age and reading ability on priming magnitude. Forty-eight participants between 7 and 22 years old read aloud primed and unprimed pseudowords, after completing a reading ability assessment. In line with predictions, the magnitude of priming for pseudowords increased with increased age when reading ability was controlled, and decreased with increased reading ability when age was controlled. Moreover, neither the age nor ability effect was significant when tested without the other. Results were not influenced by explicit memory for primed pseudowords. Thus, the present experiment provides evidence for developmental increases in word priming, as well as a potential explanation for the lack of developmental effects in previous studies.     

A new dynamical model of brainstorming: Linear, nonlinear, continuous (simultaneous) and impulsive (sequential) cases

In this paper, we extended the linear dynamical model of [Brown, V., Paulus, P. B. (1996). A simple dynamic model of social factors in group brainstorming. Small Group Research, 27, 91-114] on two accounts. First, we modelled the sequential type brainstorming using impulsive differential equations by treating each category as an impulse and tested its validity in the two experiments that investigated and demonstrated the beneficial effects of sequential priming and memory in individual brainstorming. Finally, we considered the nonlinear case of brainstorming in writing or brainwriting where dyads exchanged their ideas in a written format and that eliminated negative factors occurring in oral brainstorming (e.g., evaluation apprehension, free-riding, production blocking) and enhanced the upward performance matching, and conducted the second experiment in order to test its validity in this paradigm with the effects of sequential priming and memory. Comparisons showed good agreement between results of experiments and those of the mathematical model.     

Counterfactual thinking and confidence in blackjack: A test of the counterfactual inflation hypothesis

This research tests the idea that repeatedly generating counterfactual thoughts in response to recurring events can lead to impairments in memory for actual outcomes (i.e., counterfactual inflation hypothesis). Participants (N = 56) played 40 games of blackjack and listed their thoughts after each win. They were instructed to list evaluative counterfactuals, reflective counterfactuals, or any thoughts that came to mind following each loss. Because reflective counterfactuals focus only on the alternatives to reality, and not in addition to reality (like evaluative counterfactuals), they were expected to lead to the greatest degree of overestimations of performance and confidence for future blackjack playing. The results confirmed this hypothesis, and also demonstrated that the relationship between thought-listing instructions and confidence for the future was mediated by overestimations of performance. Thus, repeatedly generating reflective counterfactual thoughts appears to lead to a special case of imagination inflation with dysfunctional implications for future confidence and risk-taking.     

A model of working memory capacity in the radial-arm maze task

The radial arm maze is one of the most commonly used tests for assessing working memory in laboratory animals. However, to date, there exists no quantitative method of estimating working memory capacity from performance on this task. Here, we present a mathematical model of performance on the radial arm maze from which we can derive estimates of capacity. We derive explicit results for the two most commonly used measures of performance as functions of number of arms in the maze and memory capacity, assuming a uniform random search. We simulate random non-uniform search strategies. Comparing our model to previous experiments, we show that our model predicts a working memory capacity in the range of 3-9 at the level of performance observed in these experiments. This estimate is within the typical estimate of human working memory capacity. Performance of rats on large mazes (e.g. 48 arms) has been used as evidence that the working memory capacity of rats may be significantly larger than that of humans. We report that memory capacity in the range 3-9 is sufficient to explain the performance of rats in very large radial mazes. Furthermore, when we simulate non-uniform random search strategies observed in the experiments, the resulting estimates do not differ significantly from those assuming a uniform random search. We conclude that a list-based model of working memory with modest capacity is more powerful than previously expected.