Josée Turcotte

Age and synchrony effects in visuospatial working memory

Younger and older adults were administered a computerized version of the Corsi Block visuospatial working memory (VSWM) span task at either their peak or off-peak time of day and in either a high-interference (ascending order of administration, starting with short lists first) or low-interference (descending order, starting with longest lists first) format. Young adults’ span scores were highest in the ascending format. By contrast, older adults performed better in the low-interference format, replicating findings with verbal memory span studies. Although both age groups benefited from being tested at their peak time, the advantage was far greater for older adults, but only in the low-interference format; their scores on the high-interference format were not helped by peak-time testing. These findings are consistent with the suggestion that young adults’ performance on span tasks is influenced by practice and strategies, but the performance of older adults is heavily influenced by interference—which is best controlled at peak times of day. Our findings suggest that both time of testing and interference play critical roles in determining age differences in VSWM span, and both a reduction in interference and peak-time testing may be necessary to optimize older adults’ performance and to maximize the reduction in age differences.

The effect of old age on supra-span learning of visuo-spatial sequences under incidental and intentional encoding instructions.

Recent findings [Turcotte, Gagnon, & Poirier, 2005. The effect of old age on the learning of supra-span sequences. Psychology and Aging, 20, 251-260.] indicate that incidental learning of visuo-spatial supra-span sequences through immediate serial recall declines with old age (Hebbs paradigm). In this study, we examined whether strategies induced by awareness of the repeated sequence might explain age differences. Young (18-35 years old) and older (65-80 years old) participants underwent either incidental or intentional learning instructions. Results indicated that older adults demonstrated reduced learning of the repeated sequence under both incidental and intentional instructions. In comparison, young adults showed superior learning of the repeated sequence in both conditions but intentional instructions triggered faster and greater learning in this age group. The results strongly indicated that knowledge of the repeated sequence enhanced learning only in the group of young adults. Older adults were unable to translate the knowledge of the repetition into elaborate strategies that would increase recall of the repeated sequence. Other findings suggest that incidental learning in young adults was mediated by both non-conscious and conscious recollection processes.

The TNF-α-238G > A single-nucleotide polymorphism protects against memory decline in older adults with type 2 diabetes

Inflammatory markers predict memory dysfunction in elderly patients, but their contribution to memory deficits in adults with Type 2 diabetes mellitus (T2DM) is less well understood. The present study determined whether specific single-nucleotide polymorphisms in the promoter region of tumor necrosis factor-alpha (TNF-alpha) predict verbal memory in older patients with T2DM. Immediate and delayed verbal memory were assessed using word list and paragraph recall tests in a cohort of subjects with T2DM during 2 sessions, separated by 48 weeks. The presence of the TNF-alpha-238A allele, which has been shown to decrease gene expression, consistently predicted better baseline performance and protected against memory decline over a period of 48 weeks. Therefore, inflammatory mediators may be important modulators of memory function in individuals with T2DM.

Immunity to proactive interference is not a property of the focus of attention in working memory

The Focus of Attention (FOA) is the latest incarnation of a limited capacity store in which a small number of items, in this case four, are deemed to be readily accessible and do not need to be retrieved. Thus a corollary of these ideas is that those items in the FOA are always immune to proactive interference. While there is empirical support for instances of immunity to PI in short-term retention tasks that involve memory for four-item lists, there are also many instances in which PI is observed with four-item lists as well as instances where PI and immunity to PI can be shown in the same experiment. In contrast to the FOA assumptions, an alternative cue-based account predicts both the presence of PI and immunity to PI as a function of the relation between the cues available and the particular test. Three experiments contrasted the FOA assumptions and the cue-based approach in a short-term cued recall task in which PI is manipulated by testing whether the presentation of previous, similar items would interfere with immediate recall of three list items. The results indicated that even with very short lists, both PI and immunity to PI could be observed. The PI effects observed in our experiment are at odds with the FOA approach and are more readily explained using the cueing account.

A possible physiological correlate for mental flow

The relationship between mental flow and physiological coherence was investigated in three tasks. Coherence is a state defined by a particular pattern of low frequency heart rate variability (HRV), which has been related to optimal performance and positive mental states. Flow is a pleasurable performance-enhancing psychological state. In the first task, participants answered questionnaires. In the second, they played a coherence-inducing biofeedback game, and in a third, they played a flow-inducing videogame. HRV was used to measure coherence while flow was assessed using the Flow State Scales. The data revealed that coherence could be induced without flow and vice versa. More surprising, the correlations between flow and coherence were different in each of the tasks. We conclude that coherence and flow are discrete constructs despite their theoretical similarities.

Word length effects are not due to proactive interference.

In immediate serial recall short words are better recalled than long words. The word length effect has become pivotal in the development of short-term memory models. The current research tests one explanation of the word length effect; that it is related to proactive interference (PI). We report two experiments in which the relationship is directly tested. In the first experiment we show that word length effects can be observed over the first few trials in an experiment and that the effect shows itself primarily in the number of omissions made. In the second experiment we simultaneously test for PI and word length effects. Strong word length effects were present but there was little evidence for PI influencing either overall levels of recall or the word length effect. In short, no empirical support was found for PI as an explanation of the word length effect.