Brian T Stollery

There are stable individual differences in performance variability, both from moment to moment and from day to day

Individual differences in decision speed have been regarded as direct reflections of a “primitiv” functional neurophysiological characteristic, which affects performance on all cognitive tasks and so may be regarded as the “biological basis of intelligence”, or of age-related changes in mental abilities. More detailed analyses show that variability within an experimental session (WSV) is a stable individual difference characteristic and that mean choice reaction times (CRTs) are gross summary statistics that reflect variability, rather than maximum speed of performance. A total of 98 people aged from 60 to 80 years completed 36 weekly sessions on six different letter categorization tasks. After effects of practice and of circadian variability had been eliminated, individuals with lower scores on the Cattell Culture Fair intelligence test had slower CRTs and greater WSV on all tasks. A simulation study showed that the greater WSVs of low Cattell scorers led directly to the significantly greater variability of their mean CRTs from session to session. However because CRTs on tasks co-varied from session to session it was apparent that, besides being affected by WSV, individuals’ between-session variabilities (BSVs) also vary because of state changes that affect their performance from day to day. It seems that both variability in performance from trial to trial during a session and variability in average performance from day to day are correlated, stable, individual difference characteristics that vary inversely with intelligence test performance. Methodological consequences of these results for interpretations of age-related cognitive changes, for variability between as well as within individuals, for individual differences in decision speed, and for circadian variability in performance are discussed.

Smoking, drinking, and other life style factors and cognitive function in men in the Caerphilly cohort.

STUDY OBJECTIVES: To examine the cognitive function in a large, ongoing cohort study of older men, and to identify associations with social and lifestyle factors. DESIGN: A cross sectional study of cognitive function was conducted within the Caerphilly Prospective Study of Heart Disease and stroke. SETTING: The Caerphilly Study was originally set up in 1979-83 when the men were 45-59 years of age. Extensive data are available on a wide range of lifestyle and other factors of possible relevance to cognitive decline. Associations between some of these and cognitive function are reported. PARTICIPANTS: A representative sample of 1870 men aged 55-69 years. MAIN RESULTS: Age, social class, medication, and mood were found to be powerful determinants of performance. Self report data on the involvement of the men in leisure pursuits were examined by factor analysis. This indicated that the more intellectual leisure pursuits are the most strongly linked with performance. A measure of social contact showed a weak positive association with the test scores. Current cigarette smokers gave lower test cognitive function scores than either men who had never smoked, or ex-smokers. There was however no evidence of any gradient in function with the total lifetime consumption of tobacco. The disparity between these two data sets suggests that there had been prior selection of men who had originally started to smoke, but more particularly selection of those who later quit smoking. There was no significant association between alcohol consumption and cognitive function, though ex-drinkers had markedly lower test scores than either current drinkers or men who had never drunk alcohol. This seemed probably to be a consequence of an high prevalence of illness among the ex-drinkers. CONCLUSIONS: Age and social class show strong associations with cognitive function. Leisure persuits and social contact are also both positively associated. Neither tobacco smoking nor the drinking of alcohol seem to be associated with cognitive function, though there is evidence suggestive of self selection of both men who had never smoked and ex-smokers.

Cognitive function in the Caerphilly study: Associations with age, social class, education and mood

Baseline cognitive function was established for a study of pre- symptomatic cognitive decline in 1870 men from the general population aged 55–69 years as part of the third examination of the Caerphilly Study. Cognitive assessment included the AH4, a four choice serial reaction time task, a modified CAMCOG, MMSE, NART and various memory tests. Distributions and relationships with age, social class, education and mood at time of testing are presented for a younger population than has previously been available. Multiple linear regression showed cognitive function to be independently associated with all four factors. The age effect was equivalent to one half of a standard deviation (SD) in CRT and AH4 scores. Only the NART score was not associated with age, supporting the use of NART score as an estimate of pre-morbid IQ. The largest age adjusted differences between men with low and normal mood were for the AH4 (3 points, t=5.6, p<0.0001) and the CAMCOG (2 points, t=5.8, p<0.0001). The smallest age adjusted effect of mood was for the CRT (33ms, t=2.14, p=0.32) and the MMSE (0.4 points, t=2.97, p=0.003). Age, mood and education adjusted social class effects were very large ranging between around 0.5 SD for the CRT, and 1.0 SD for the AH4 and NART, respectively. For educational status age, mood and social class adjusted differences were also substantial with tests for trend showing the largest differences for the NART (t=12, p<0.0001) and modified CAMCOG (t=10.6, p<0.0001) with the smallest differences for the CRT (t=2.73, p=0.006).

The effects of age and task domain on dual task performance: A meta-analysis

Recent research has provided mixed findings as to whether older adults find dual tasking problematic. Here, we examined whether methodological variations across studies can account for the discrepancies in the literature. Meta-analyses conducted on the results of 34 studies conducted between 1981 and 2003 found a strong overall effect size (d = .68), which indicated a clear age-related dual tasking impairment. However, this effect size was not representative of all the individual studies reported. Subsequent analyses, using an analysis of variance analogue (Hedges & Olkin, 1985), investigated potential moderators responsible for the variability in the effect sizes across studies. These secondary analyses included a comparison of dependent measure used, whether baseline differences in performance had been controlled for, and task domain. Task domain was found to be the critical moderator variable. Notably, tasks with a substantial controlled processing, or motor component showed greater dual task impairment than tasks that were relatively simple or relied on automatic processing.

Memory processing and the glucose facilitation effect: The effects of stimulus difficulty and memory load

Abstract Previous research has consistently found enhancement of memory after the ingestion of a glucose containing drink. The aims of the present study were to specify more precisely the nature of this facilitation by examining the cognitive demand hypothesis. This hypothesis predicts greater glucose induced facilitation on tasks that require significant mental effort. In two experiments, both employing an unrelated sample design, participants consumed either 25 g of glucose or a control solution. In experiment 1, participants first studied low and high imagery word-pairs and memory was assessed 1-, 7- and 14-days later by cued recall. Overall, glucose enhanced both encoding and consolidation processes only for the more difficult low imagery pairs. In experiment 2, the degree of mental effort in a verbal memory task was manipulated in two ways: (1) by varying the phonological similarity of the words; and (2) by varying the length of word lists. Glucose was found to enhance memory only for longer word lists. These data are consistent with the idea that glucose is especially effective in demanding memory tasks, but place some limits on the forms of difficulty that are susceptible to enhancement.

The Automated Cognitive Test (ACT) system

The ACT system is a key-press, menu-driven system for selecting, administering, and storing raw data from a series of specially designed psychological tasks. Associated task analysis programs process the raw data and store the resulting summary data for later statistical analysis. The system utilizes a cognitive approach to assessments of marginal toxicity by employing multiple performance parameters to specify a profile of deficits that, on the basis of a tasks internal structure, can be related to functionally discrete cognitive systems. The tasks have been developed from a consideration of current cognitive theory and the areas of cognition include those of learning, memory, attention, reasoning, verbal, and spatial abilities. The ACT system is described in terms of its four major components: the cognitive tasks, the stimulus materials, the analysis methods, and the process of saving and combining summary data into files suitable for transfer to statistical analysis programs. The system thus automates the data collection to statistical analysis process.

An Exploration of the Existential Experiences of Patients Following Curative Treatment for Cancer: Reflections from a U.K. Sample

The existential experiences associated with cancer diagnosis and treatment are well researched, but the posttreatment phase is relatively underexplored. Using semistructured interviews and theory-led thematic analysis this qualitative study investigated the existential experiences of eight cancer survivors who had successfully completed curative treatment. Being in remission had led to deep existential reflections (i.e., death anxiety, freedom, isolation, and meaning making), and some participants faced considerable challenges that affected their emotional well-being. Understanding cancer survivors’ existential challenges should enable health care professionals to engage with the emerging shift from the predominantly medically focused posttreatment care to a more holistic approach.

Cognitive neurotoxicology: A luxury or necessity?

Impaired psychological test performance is often observed at concentrations of a neurotoxicant below those producing harmful effects on other organ systems. The importance of this distinctive susceptibility lies in the opportunity it provides for the early detection of dysfunction. From this perspective, it is essential to evolve sensitive psychological methods for studying these states of marginal toxicity. It is argued that a cognitive approach provides the necessary degree of sensitivity and specificity for characterizing these states. Given the growing interest in using cognitive models to assess minor dysfunction in areas outside neurotoxicology, it is further argued that theoretically motivated methods can no longer be considered a luxury for neurotoxicological work. It is concluded that there are at least two advantages to this approach. First, it provides a theoretical framework for organising data. Second, establishing and developing links to substantive areas of cognitive investigation outside neurotoxicology will allow cross-fertilization to occur on a scientific level and provide a more convincing basis for action on a regulatory level.

Glucose and memory: The influence of drink, expectancy, and beliefs

RationaleAn increasing number of studies suggest that glucose can enhance aspects of memory and the central methodology is the use of the glucose–placebo design. One critical issue therefore is separating the pharmacological effects of glucose from the expectancies created by consuming a drink that might contain glucose.ObjectiveA modified balanced placebo design examined the role that expectancy and belief about the drink consumed has on the pharmacological changes observed following glucose consumption.MethodNinety-three participants, allocated according to a drink (glucose, placebo) × message (told glucose, told nothing, told placebo) unrelated design, were administered tasks assessing immediate and delayed verbal free recall, spatial recognition and semantic verification. Each task has some evidence for hippocampus involvement, and variations in task difficulty were used to assess the idea that glucose effects are sensitive to task difficulty.ResultsWhile the messages biased drink judgements in the expected direction, judgements of drink content were at chance and glucose only enhanced delayed free recall. The subtle effects of the messages did not modify the glucose enhancement. However, believing glucose had been consumed showed an independent improvement in delayed free recall. There was no evidence that task complexity enhanced the glucose effect.ConclusionsThe findings indicate that expectancy effects are unlikely to be confused with glucose enhancements, but beliefs about consuming glucose can augment performance on delayed free recall. The discussion considers the hippocampus and complexity hypotheses of glucose’s mode of action and proposes the routine collection of drink beliefs in future studies.

Between-sex differences in romantic jealousy: substance or spin? A qualitative analysis

An influential evolutionary account of romantic jealousy proposes that natural selection shaped a specific sexually-dimorphic psychological mechanism in response to relationship threat. However, this account has faced considerable theoretical and methodological criticism and it remains unclear whether putative sex differences in romantic jealousy actually exist and, if they do, whether they are consistent with its predictions. Given the multidimensional nature of romantic jealousy, the current study employed a qualitative design to examine these issues. We report the results of sixteen semi-structured interviews that were conducted with heterosexual men and women with the purpose of exploring the emotions, cognitions and behaviors that formed their subjective, lived experience in response to relationship threat. Interpretative phenomenological analysis revealed four super-ordinate themes (“threat appraisal”, “emotional episodes”, “sex-specific threat” and “forgive and forget”) and unequivocal sex differences in romantic jealousy consistent with the evolutionary account. Self-esteem, particularly when conceptualized as an index of mate value, emerged as an important proximal mediator for both sexes. However, specific outcomes were dependent upon domains central to the individuals self concept that were primarily sex-specific. The findings are integrated within the context of existing self-esteem and evolutionary theory and future directions for romantic jealousy research are suggested.