Prospective memory across the lifespan: Investigating the contribution of retrospective and prospective processes

Prospective memory performance follows an inverted U-shaped function across the lifespan. Findings on the relative contribution of purely prospective memory and retrospective memory processes within prospective memory to this trajectory are scarce and inconclusive. We analyzed age-related differences in prospective memory performance across the lifespan in a cross-sectional design including six age groups (N = 99, 7–83 years) and investigated possible mechanisms by experimentally disentangling the relative contributions of retrospective memory and purely prospective memory processes. Results confirmed the inverted U-shaped function of prospective memory performance across the lifespan. A significant interaction between process type and age group was observed indicating differential relative contributions of retrospective memory and purely prospective memory processes on the development of prospective memory performance. Our results showed that mainly the pure prospective memory processes within prospective memory lead to lower prospective memory performance in young children and old adults. Moreover, the relative contributions of the retrospective memory and purely prospective memory processes are not uniform at both ends of the lifespan, i.e., in later adulthood the purely prospective memory processes seem to determine performance to an even greater extent than in childhood. Nevertheless, age effects were also observed in the retrospective component which thus contributed to the prospective memory performance differences between the age groups.     

Does multitasking mediate the relationships between episodic memory,attention, executive functions and apathetic manifestations in traumatic brain injury?

Apathy is frequently described in patients with traumatic brain injury (TBI); its negative consequences particularly affect functional independence. Among apathetic manifestations, lack of initiative and lack of interest have mainly been associated with cognitive impairments. However, few studies have been conducted to precisely identify the underlying cognitive processes. Our aims were (1) to determine the best predictor of apathy from among several cognitive processes, including episodic memory and attention/executive mechanisms and multitasking, and (2) to examine to what extent multitasking could mediate the relationships between specific cognitive processes and lack of initiative/interest. Seventy participants (34 patients with TBI matched with 36 control participants) were given a questionnaire to assess anxio‐depressive symptoms, four tasks to assess specific cognitive processes, and one task to assess real‐life multitasking. Participants’ relatives completed an apathy questionnaire. Multitasking, as assessed by the number of goals not achieved, was the only significant predictor of apathetic manifestations. In addition, the mediation analyses revealed that multitasking performance mediated the relationships between verbal episodic memory and lack of initiative/interest, whereas executive and attentional functions were only indirectly related to lack of initiative/interest due to their significant impacts on multitasking. These results shed new light on the aetiology of apathetic manifestations in patients with TBI, indicating how specific cognitive deficits are expressed in real‐life multitasking, and consequently, how they may lead to the development and/or maintenance of apathetic manifestations.     

An analysis of factors affecting wrong-way driving at a highway entrance using a driving simulator among older drivers with cognitive decline

About 200 highway wrong-way driving cases occur annually in Japan, of which about 70% are caused by older drivers. The number of these cases has remained consistent despite adoption of full-fledged measures against wrong-way driving, thus demonstrating the need for further measures. Reports indicate that older drivers include those with cognitive decline. Moreover, it has been revealed that drivers over 75 years of age who caused wrong-way driving had lower test scores in the usual cognitive function tests performed at the time of licence renewal. However, there is no clear evidence on the relationship between cognitive decline and driving behaviour that stimulates wrong-way driving. In this paper, we reproduced a wrong-way driving approaching a right turn to an expressway exit in a virtual environment using a driving simulator for older drivers, including those with mild cognitive impairment (MCI). In addition to the measurement of driving behaviour and eye-tracking during simulator driving, we conducted a cognitive function test to investigate the relationship between driving behaviour and visual behaviour factors that initiate reverse running and cognitive decline. The results revealed that the reason for the start of a highway wrong-way driving may be a human error at the recognition stage of overlooking a visual wrong-way driving countermeasure, or a human error at the judgement stage of failing to suppress action despite noticing the visual countermeasure. Additionally, attentional and executive functions were related to the wrong-way initiative, although MCI did not affect it. This suggests that those who could not control their wrong-way driving behaviour despite observing the signs had specific executive function deficits.     

Linking vitamin D status,executive functioning and self‐perceived mental health in adolescents through multivariate analysis: A randomized double‐blind placebo control trial

The aim of the present randomized double‐blind placebo control trial was to investigate if vitamin D supplementation had an effect on vitamin D status, executive functioning and self‐perceived mental health in a group of Norwegian adolescents during winter time. Fifty adolescents were randomly assigned into an intervention group (vitamin D pearls) or a control group (placebo pearls). Before (pre‐test in December/January) and after (post‐test in April/May) the intervention period the participants were exposed to a test procedure, consisting of blood draw, completion of cognitive tests (Tower of Hanoi and Tower of London), and the Youth Self‐report version of the Child Behavior Checklist. Multivariate data analysis showed that participants with low vitamin D status scored worse on the Tower of London tests and the more difficult sub‐tasks on the Tower of Hanoi tests. They also had a tendency to report higher frequency of externalizing behavior problems and attention deficit. At pre‐test, the overall mean vitamin D status measured as 25‐hydroxy vitamin D was 42 nmol/L, defining deficiency (Intervention group = 44 nmol/L, Control group = 39 nmol/L). However, vitamin D supplementation caused a significant increase in vitamin D status resulting in a sufficient level in the Intervention group at post‐test (mean 62 nmol/L). The results also revealed that the intervention group improved their performance on the most demanding sub‐tasks on the ToH. Overall, the study indicates that vitamin D status in adolescents may be important for both executive functioning and mental health.     

The association between the behavior rating inventory of executive functioning and cognitive testing in children diagnosed with a brain tumor

Pediatric brain tumor survivors (PBTS) suffer from cognitive late effects, such as deteriorating executive functioning (EF). We explored the suitability of the Behavior Rating Inventory of Executive Function (BRIEF) to screen for these late effects. We assessed the relationship between the BRIEF and EF tasks, and between the BRIEF-Parent and BRIEF-Teacher, and we explored the clinical utility. Eighty-two PBTS (8–18 years) were assessed with EF tasks measuring attention, cognitive flexibility, inhibition, visual-, and working memory (WM), and with the BRIEF-Parent and BRIEF-Teacher. Pearson’s correlations between the BRIEF and EF tasks, and between the BRIEF-Parent and BRIEF-Teacher were calculated. The BRIEF-Parent related poorly to EF tasks (rs < .26, ps > .01), but of the BRIEF-Teacher the WM-scale, Monitor-scale, Behavioral-Regulation-Index, and Meta-cognition-Index, and Total-score (rs > .31, ps < .01) related significantly to some EF tasks. When controlling for age, only the WM scale and Total score related significantly to the attention task (ps < .01). The inhibit scales of the BRIEF-Parent and BRIEF-Teacher correlated significantly (r = .33, p < .01). Children with clinically elevated scores on BRIEF scales that correlated with EF tasks performed worse on all EF tasks (ds 0.56–1.23, ps < .05). The BRIEF-Teacher Total and Index scores might better screen general EF in PBTS than the BRIEF-Parent. However, the BRIEF-Teacher is also not specific enough to capture separate EFs. Solely relying on the BRIEF as a screening measure of EFs in BPTS is insufficient. Questionnaires and tasks give distinctive, valuable information.     

Response inhibition and interference control: Effects of schizophrenia,genetic risk,and schizotypy

The ability to inhibit inappropriate responses and suppress irrelevant information is a core feature of executive control. In this study, we provide a detailed analysis of prepotent response inhibition and interference in patients with schizophrenia. To further test the role of genetic factors and subclinical schizophrenia‐like traits, we additionally studied clinically unaffected, first‐degree relatives of schizophrenia patients and assessed dimensions of schizotypy in both relatives and healthy controls. Inhibition and interference control were assessed using a battery comprising the antisaccade, Stroop, stop signal, go/no‐go, flanker, and Simon tasks. Schizophrenia patients differed from both relatives and controls in making more errors on the antisaccade task and having longer response times on the Stroop task, especially the incongruent condition. Patients also had general, that is, condition independent, increases in reaction times on the go/no‐go and flanker tasks and made more errors on the flanker and Simon tasks, suggesting general performance impairments independent of inhibitory demand. Relatives were characterized by hypometric antisaccade amplitude gain despite normal prosaccades, suggesting a selective deficit in non‐standard sensorimotor transformations. Schizotypy was correlated with inhibitory performance across a number of tasks in both relatives and controls. Generally, these effects were independent of verbal intelligence levels. Overall, the findings point to rather selective impairments of inhibitory control in the schizophrenia spectrum and confirm a previously observed deficit in antisaccade spatial accuracy as an endophenotype of schizophrenia.     

Vagueness and Blurry Sets

This paper presents a new theory of vagueness, which is designed to retain the virtues of the fuzzy theory, while avoiding the problem of higher-order vagueness. The theory presented here accommodates the idea that for any statement S ₁ to the effect that Bob is bald is x true, for x in [0,1], there should be a further statement S ₂ which tells us how true S ₁ is, and so on – that is, it accommodates higher-order vagueness – without resorting to the claim that the metalanguage in which the semantics of vagueness is presented is itself vague, and without requiring us to abandon the idea that the logic – as opposed to the semantics – of vague discourse is classical. I model the extension of a vague predicate P as a blurry set, this being a function which assigns a degree of membership or degree function to each object o, where a degree function in turn assigns an element of [0,1] to each finite sequence of elements of [0,1]. The idea is that the assignment to the sequence 0.3,0.2, for example, represents the degree to which it is true to say that it is 0.2 true that o is P to degree 0.3. The philosophical merits of my theory are discussed in detail, and the theory is compared with other extensions and generalisations of fuzzy logic in the literature.     

On the evolutionary origins of executive functions

In this paper it is proposed that the prefrontal lobe participates in two closely related but different executive function abilities: (1) "metacognitive executive functions": problem solving, planning, concept formation, strategy development and implementation, controlling attention, working memory, and the like; that is, executive functions as they are usually understood in contemporary neuroscience; and (2) "emotional/motivational executive functions": coordinating cognition and emotion/motivation (that is, fulfilling biological needs according to some existing conditions). The first one depends on the dorsolateral prefrontal areas, whereas the second one is associated with orbitofrontal and medial frontal areas. Current tests of executive functions basically tap the first ability (metacognitive). Solving everyday problems (functional application of executive functions), however, mostly requires the second ability (emotional/motivational); therefore, these tests have limited ecological validity. Contrary to the traditional points of view, recent evidence suggests that the human prefrontal lobe is similar to other primates and hominids. Other primates and hominids may possess the second (emotional executive functions) prefrontal ability, -but not the first (metacognitive executive functions) one. It is argued that metacognitive executive functions are significantly dependent on culture and cultural instruments. They probably are the result of the development and evolution of some "conceptualization instruments"; language (and written language as an extension of oral language) may represent the most important one. The second executive function ability (emotional/motivational) probably is the result of a biological evolution shared by other primates.