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1.
Article En | MEDLINE | ID: mdl-36317287

BACKGROUND: Psychosocial interventions improve the wellbeing and quality of life of People Living with Dementia (PLWD) and their family carers; but due to their complexity it can be challenging to identify mechanisms of action. We reviewed process evaluations that have sought to elucidate how these interventions work, to inform their implementation. METHOD: We systematically reviewed process evaluations of studies evaluating psychosocial interventions for PLWD in their own home and/or their family carers. We rated study quality using the Mixed Methods Appraisal Tool. We described, with reference to Medical Research Council (2015) process evaluation guidance, how implementation, mechanisms of impact and contextual factors were investigated; and describe commonalities in the mechanisms of action identified across studies. RESULTS: Twenty four included studies evaluated the processes of 22 interventions. These studies collectively applied five frameworks; almost all frameworks' advised evaluations were theory-based and used mixed-methods analyses, but only 5/24 evaluation designs were informed by the intervention theory and 8/24 used mixed methods. 8/24 evaluations considered contextual factors in their design, though 20/24 cited contextual factors in findings. Interventions were more successful where PLWD were motivated and aware of potential benefits, and when carers could support engagement and were themselves supported by the intervention. How the intervention aligned with participants' current needs and stage of dementia were key influencing factors. CONCLUSION: Knowing how interventions can influence change for community-dwelling people with dementia and their family carer's will improve translation of trial findings into practice. Robust, theory-driven process evaluations can enable this.


Caregivers , Dementia , Humans , Caregivers/psychology , Quality of Life/psychology , Independent Living , Dementia/therapy , Dementia/psychology , Psychosocial Intervention
2.
BMJ Open ; 12(6): e054613, 2022 06 09.
Article En | MEDLINE | ID: mdl-35680268

INTRODUCTION: New Interventions for independence in Dementia Study (NIDUS)-Family is an Alzheimer's Society funded new manualised, multimodal psychosocial intervention to support people living with dementia (PLWD) to achieve goals that they and their family carers set, towards living as independently and as well as possible at home for longer. This process evaluation will be embedded within the NIDUS-Family Randomised Controlled Trial intervention-arm (n=199), testing how the intervention influences change, as measured by goal attainment. The evaluation will test, refine and develop the NIDUS-Family theoretical model, associated causal assumptions and logic model to identify key mechanisms of impact, implementation and contextual factors influencing the intervention's effectiveness. Findings will inform how the programme is implemented in practice. METHODS AND ANALYSIS: The process evaluation will be theory driven and apply a convergent mixed-methods design. Dyads (PLWD and family carer) will be purposively sampled based on high or low Goal Attainment Scaling scores (trial primary outcome). Qualitative interviews with dyads (approx. n=30) and their respective facilitators post-trial will explore their experiences of receiving and delivering the intervention. Interviews will be iteratively thematically analysed. Matching observational quantitative data will be collected concurrently from videorecordings and/or audiorecordings of NIDUS-Family dyad trial sessions. Further quantitative data will be collected through an acceptability questionnaire for all intervention-arm dyads (n=199). Mixed-method integration will use an interactive analysis strategy, considering qualitative and quantitative findings through mixed-method matrix for dyadic level 'case studies', and a joint display for 'population' level analysis and interpretation. ETHICS AND DISSEMINATION: Ethical approval was received from Camden & Kings Cross Research Ethics Committee (REC). Study reference: 19/LO/1667. IRAS project ID: 271 363. This work is carried out within the UCL Alzheimer's Society Centre of Excellence (grant 300) for Independence at home, NIDUS programme.Findings will be disseminated through publications and conferences, and as recommendations for the implementation study and strategy. TRIAL REGISTRATION NUMBER: ISRCTN11425138.


Alzheimer Disease , Dementia , Alzheimer Disease/therapy , Caregivers/psychology , Dementia/psychology , Dementia/therapy , Humans , Randomized Controlled Trials as Topic , Rivers , Surveys and Questionnaires
3.
J Exp Child Psychol ; 217: 105351, 2022 05.
Article En | MEDLINE | ID: mdl-35093667

Infants growing up in an environment where more than one language is spoken tend to follow the early milestones of early language development. This is an impressive achievement given that they are learning two languages while receiving reduced exposure to each of these languages compared with monolingual infants. This increased variability in their linguistic environment may lead to adjustments in the way bilingual infants process visual and auditory speech. This study aimed to clarify the influence of infant bilingualism on the development of audiovisual speech integration. Using eye tracking and a McGurk paradigm, we studied face scanning patterns when 7- to 10-month-old infants were viewing articulation of audiovisually congruent and incongruent syllables. We found that monolingual infants decreased their attention to the mouth and increased their attention to the eyes of speaking faces when presented with incongruent articulation, typically leading to the McGurk illusion during adulthood. In bilingual infants, no differences in face scanning patterns were observed between audiovisually congruent and incongruent articulation, suggesting that the increased variability in their speech experience may lead to more tolerance to articulatory inconsistencies. These results suggest that the development of audiovisual speech perception is influenced by infants' language environment.


Illusions , Multilingualism , Speech Perception , Adult , Humans , Infant , Mouth , Visual Perception
4.
Neuropsychol Rehabil ; 32(10): 2534-2543, 2022 Dec.
Article En | MEDLINE | ID: mdl-34323664

ABSTRACTIn this study, we validate an earlier proposal for an abridged 17-item National Adult Reading Test (NART) by comparing its performance in estimating full-scale IQ against both the full test and the Spot-the-Word 2 (STW-2) test in a new cohort. We also compare the performance of the 17-item NART to two previous attempts to shorten this test, the Mini-NART and the Short NART. Findings include that NART 17 is numerically stronger and statistically equivalent to the other short variants, the full 50-word NART, and STW-2. Unlike the Short NART, the 17-item NART is usable for participants of all ability levels rather than only those with low reading ability, while offering equally precise premorbid estimates. We also compute that two-thirds of STW-2 is ostensibly redundant for full-scale IQ estimation and we, therefore, propose that, subject to additional verification in an independent sample, an abridged version of this test may also benefit clinical practice.


Intelligence , Reading , Adult , Humans , Intelligence Tests , Wechsler Scales , Cognition
5.
Q J Exp Psychol (Hove) ; 75(1): 130-147, 2022 Jan.
Article En | MEDLINE | ID: mdl-34092150

The development of verbal fluency is associated with the maturation of executive function skills, such as the ability to inhibit irrelevant information, shift between tasks, and hold information in working memory. Some evidence suggests that multilinguistic upbringing may underpin disadvantages in verbal fluency and lexical retrieval, but can also afford executive function advantages beyond the language system including possible beneficial effects in older age. This study examined the relationship between verbal fluency and executive function in 324 individuals across the lifespan by assessing the developmental trajectories of English monolingual and multilingual children aged 7-15 years (N = 154) and adults from 18 to 80 years old (N = 170). The childhood data indicated patterns of improvement in verbal fluency and executive function skills as a function of age. Multilingual and monolingual children had comparable developmental trajectories in all linguistic and non-linguistic measures used in the study with the exception of planning, for which monolingual children showed a steeper improvement over the studied age range relative to multilingual children. For adults, monolinguals and multilingual participants had comparable performance on all measures with the exception of nonverbal inhibitory control and response times on the Tower of London task: monolinguals showed a steeper decline associated with age. Exploratory factor analysis indicated that verbal fluency was associated with working memory and fluid intelligence in monolingual participants but not in multilinguals. These findings raise the possibility that early acquisition of an additional language may impact on the development of the functional architecture serving high-level human cognition.


Executive Function , Multilingualism , Adolescent , Adult , Aged , Aged, 80 and over , Child , Cross-Sectional Studies , Humans , Language , Language Tests , Middle Aged , Young Adult
7.
Q J Exp Psychol (Hove) ; 73(11): 1757-1773, 2020 Nov.
Article En | MEDLINE | ID: mdl-32419614

The modern understanding of the term metacognition encompasses two levels of processing: a lower level awareness or knowledge of one's own thoughts and a higher level regulation or control of our thinking. Metacognition, therefore, bears conceptual similarity with executive function: both are concerned with top-down monitoring and control of cognition in the service of ongoing goal-directed behaviour. Previous studies have shown a possible executive function advantage in multilingual speakers but also a possible disadvantage in metacognitive processing. To progress theory on metacognitive processing and the relationship with executive function and linguistic experience across the lifespan, we conducted a study testing 330 healthy individuals in four age groups from 7 to 80 years old. All participants performed a metacognition task and two measures of executive function, which included the Simon task and the Tower of London task. Half the participants were multilingual speakers since birth. We built developmental trajectories of metacognitive and executive function across the lifespan. The best metacognitive efficiency was observed in mid-adulthood, whereas the best executive function processing reached its peak in young adulthood. A steep cognitive decline was observed in older age, while metacognitive efficiency was preserved. Exploratory factor analysis indicated that metacognition and executive function are served by different factors across all ages. Contrary to previous findings in the bilingual literature, a multilinguistic experience conferred neither any significant advantage nor disadvantage in both executive function and metacognitive processing across the lifespan.


Executive Function , Metacognition , Multilingualism , Adolescent , Adult , Aged , Aged, 80 and over , Child , Humans , Middle Aged , Young Adult
8.
Headache ; 60(6): 1124-1131, 2020 06.
Article En | MEDLINE | ID: mdl-32282067

OBJECTIVE: We studied the color of lighting chosen as comfortable for reading by individuals with migraine and controls. We explored the effects of the chosen color on visual performance. BACKGROUND: It has been reported that individuals who experience migraine with aura (MWA) choose, as comfortable for reading, light that is more strongly saturated in color than that chosen by individuals without migraine. METHODS: A convenience sample of 18 individuals who experienced MWA, 18 without aura, and 18 controls without migraine participated in a cross-sectional laboratory study at Anglia Ruskin University. We used an Intuitive Colorimeter that illuminated text with colored light and permitted the separate control of hue (color) and saturation (strength of color) without a change in luminance. We selected individuals with migraine and healthy controls from the general population. They were headache-free in the 48 hours prior to testing. We used a routine that permitted the selection of the most comfortable hue from 12 alternatives and then alternately optimized the saturation and hue using small changes, thereby allowing for color adaptation. Visual performance at a word search task was measured under white light and under light of a color chosen as comfortable, using colored lenses. RESULTS: Healthy individuals chose light with chromaticity close to the Planckian locus, which approximates the chromaticities of daylight and most electric lighting. The distance from the locus averaged 0.029 (SD 0.021). Individuals who experienced MWA chose strongly saturated colors well away from the Planckian locus (average distance 0.056, SD 0.022). Individuals who experienced migraine without aura chose intermediate chromaticities (average distance 0.034, SD 0.022). Overall there was a large statistically significant difference between participant groups that explained 24% variance. Visual search time of individuals with migraine aura decreased from 22.5 to 16.8 s when light of the chosen color was provided using tinted lenses (the average increase in search speed was 45.7%). The lenses had no statistically significant effect on the performance of individuals without migraine aura. CONCLUSIONS: Individuals who experienced MWA selected as comfortable colors that deviated from the lighting typically experienced in everyday life. Possibly, individuals who experience MWA may be more susceptible to photophobia under typical lighting. Visual performance was improved using lenses that provided light of the chosen comfortable color. The spectral power of that choice showed no evident relationship to melanopic energy (energy captured by the intrinsically photosensitive retinal ganglion cells).


Choice Behavior/physiology , Color Perception/physiology , Lighting , Migraine with Aura/physiopathology , Pattern Recognition, Visual/physiology , Adolescent , Adult , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Migraine without Aura/physiopathology , Reading , Young Adult
9.
PLoS One ; 15(4): e0231288, 2020.
Article En | MEDLINE | ID: mdl-32315339

We evaluate brain structure sensitivity to verbal interference in a sentence interpretation task, building on previously reported evidence that those with better control of verbal interference show higher grey matter density in the posterior paravermis of the right cerebellum. We compare brain structure sensitivity to verbal interference control across two groups, English monolingual (N = 41) and multilingual (N = 46) adults. Using voxel-based morphometry, our primary goal was to identify and explore differences in regional patterns of grey matter sensitivity to performance on the sentence interpretation task, controlling for group variability in age, nonverbal reasoning and vocabulary knowledge. There was no group difference in performance but there was a significant group effect in grey matter sensitivity to task performance in our region of interest: stronger sensitivity in the paravermis in bilinguals compared to monolinguals in accuracy performance in the high (relative to low) verbal interference condition. This effect was observed when the linguistic interference was presented in an unfamiliar language (Greek) but not when presented in the familiar language (English). Our findings suggest that multilanguage acquisition mediates regional involvement within the language network, conferring enhanced functional plasticity within structures (including the paravermis) in the service of control of linguistic interference.


Gray Matter/physiology , Multilingualism , Speech Perception , Adolescent , Adult , Aged , Aged, 80 and over , Brain Mapping , Female , Humans , Magnetic Resonance Imaging/methods , Male , Middle Aged , United Kingdom , Young Adult
10.
Cognition ; 200: 104252, 2020 07.
Article En | MEDLINE | ID: mdl-32151855

Research on speech comprehension in noise indicates that a multilinguistic experience may confer advantages in filtering out verbal interference, an effect observed both in children acquiring two or more languages since birth (Filippi, Morris, Richardson, et al., 2015) and in second language learner adults (Filippi, Leech, Thomas, et al., 2012). A possible interpretation for this advantage is that the multilingual mind is "trained" to control interference from the language not in use. This constant effort may support optimization of cognitive resources that are necessary for successfully selecting, processing and interpreting complex linguistic information. The present study aimed to extend this line of research by including a non-verbal interference condition. 209 typically developing children (132 English monolinguals and 77 multilinguals from different linguistic backgrounds) carried out a sentence interpretation task in the presence of verbal and non-verbal interference. We found no evidence for a reliable group difference in our data. Instead, findings indicated that background cognitive ability and socioeconomic status were the best indicators of successful control of interference, irrespective of whether participants were bilingual or monolingual. These findings are discussed in the light of previous research and, more widely, on the account of the current debate on the bilingual advantage.


Multilingualism , Speech Perception , Adult , Child , Comprehension , Humans , Language , Speech
11.
Neuropsychol Rehabil ; 30(1): 1-14, 2020 Jan.
Article En | MEDLINE | ID: mdl-29526134

To evaluate impact of neurological injury on cognitive performance it is typically necessary to derive a baseline (or "premorbid") estimate of a patient's general cognitive ability prior to the onset of impairment. In this paper, we consider a range of common methods for producing this estimate, including those based on current best performance, embedded "hold/no-hold" tests, demographic information, and word reading ability. Ninety-two neurologically healthy adult participants were assessed on the full Wechsler Adult Intelligence Scale - Fourth Edition (WAIS-IV; Wechsler, D. (2008). Wechsler Adult Intelligence Scale (4th ed.). San Antonio, TX: Pearson Assessment.) and on two widely used word reading tests: National Adult Reading Test (NART; Nelson, H. E. (1982). National Adult Reading Test (NART): For the assessment of premorbid intelligence in patients with dementia: Test manual. Windsor: NFER-Nelson.; Nelson, H. E., & Willison, J. (1991). National Adult Reading Test (NART). Windsor: NFER-Nelson.) and Wechsler Test of Adult Reading (WTAR; Wechsler, D. (2001). Wechsler Test of Adult Reading: WTAR. San Antonio, TX: Psychological Corporation.). Our findings indicate that reading tests provide the most reliable and precise estimates of WAIS-IV full-scale IQ, although the addition of demographic data provides modest improvement. Nevertheless, we observed considerable variability in correlations between NART/WTAR scores and individual WAIS-IV indices, which indicated particular usefulness in estimating more crystallised premorbid abilities (as represented by the verbal comprehension and general ability indices) relative to fluid abilities (working memory and perceptual reasoning indices). We discuss and encourage the development of new methods for improving premorbid estimates of cognitive abilities in neurological patients.


Intelligence Tests , Adolescent , Adult , Aged , Educational Status , Humans , Intelligence , Middle Aged , Neuropsychological Tests , Occupations , Young Adult
12.
Behav Sci (Basel) ; 9(8)2019 Aug 19.
Article En | MEDLINE | ID: mdl-31430913

Bilingual individuals have been reported to show enhanced executive function in comparison to monolingual peers. However, the role of adverse emotional traits such as trait anxiety and rumination in bilingual cognitive control has not been established. Attentional Control Theory holds that anxiety disproportionately impacts processing efficiency (typically measured via reaction time) in comparison to accuracy (performance effectiveness). We administered eye tracking and behavioural measures of inhibition to young, healthy monolingual and highly proficient bilingual adults. We found that trait anxiety was a reliable risk factor for decreased inhibitory control accuracy in bilingual but not monolingual participants. These findings, therefore, indicate that adverse emotional traits may differentially modulate performance in monolingual and bilingual individuals, an interpretation which has implications both for ACT and future research on bilingual cognition.

14.
Q J Exp Psychol (Hove) ; 72(6): 1354-1363, 2019 Jun.
Article En | MEDLINE | ID: mdl-30081734

Recent evidence has challenged long-standing claims that multi-language acquisition confers long-term advantages in executive function and may protect against age-related cognitive deterioration. We assessed evidence for a bilingual advantage in older monolingual and bilingual residents matched on age, gender, and socioeconomic status. A comprehensive battery of tests was administered to measure non-verbal reasoning, working memory capacity, visuo-spatial memory, response inhibition, problem solving, and language proficiency. Analyses, including Bayes factors, revealed comparable performance in both groups, with no significant differences on any task (and the only trend, found for the Tower of London task performance, indicated a monolingual advantage). Overall, therefore, our findings run counter to the bilingual advantage hypothesis. We consider the implications of our study and offer suggestions for future work in this area.


Aging/physiology , Cognitive Reserve/physiology , Executive Function/physiology , Memory, Short-Term/physiology , Memory/physiology , Multilingualism , Thinking/physiology , Aged , Bayes Theorem , Female , Humans , Male
15.
Front Psychol ; 9: 1943, 2018.
Article En | MEDLINE | ID: mdl-30459671

Faces capture and maintain infants' attention more than other visual stimuli. The present study addresses the impact of early language experience on attention to faces in infancy. It was hypothesized that infants learning two spoken languages (unimodal bilinguals) and hearing infants of Deaf mothers learning British Sign Language and spoken English (bimodal bilinguals) would show enhanced attention to faces compared to monolinguals. The comparison between unimodal and bimodal bilinguals allowed differentiation of the effects of learning two languages, from the effects of increased visual communication in hearing infants of Deaf mothers. Data are presented for two independent samples of infants: Sample 1 included 49 infants between 7 and 10 months (26 monolinguals and 23 unimodal bilinguals), and Sample 2 included 87 infants between 4 and 8 months (32 monolinguals, 25 unimodal bilinguals, and 30 bimodal bilingual infants with a Deaf mother). Eye-tracking was used to analyze infants' visual scanning of complex arrays including a face and four other stimulus categories. Infants from 4 to 10 months (all groups combined) directed their attention to faces faster than to non-face stimuli (i.e., attention capture), directed more fixations to, and looked longer at faces than non-face stimuli (i.e., attention maintenance). Unimodal bilinguals demonstrated increased attention capture and attention maintenance by faces compared to monolinguals. Contrary to predictions, bimodal bilinguals did not differ from monolinguals in attention capture and maintenance by face stimuli. These results are discussed in relation to the language experience of each group and the close association between face processing and language development in social communication.

16.
Front Psychol ; 9: 1818, 2018.
Article En | MEDLINE | ID: mdl-30319512

Between-group variability in socioeconomic status (SES) has been identified as a potentially important contributory factor in studies reporting cognitive advantages in bilinguals over monolinguals (the so called "bilingual advantage"). The present study addresses the potential importance of this alternative explanatory variable in a study of low and high SES bilingual and monolingual performance on the Simon task and the Tower of London (TOL) task. Results indicated an overall bilingual response time advantage on the Simon task, despite equivalent error rates. Socioeconomic status was an important modulator in this effect, with evidence that bilingualism may be particularly important in promoting speed of processing advantages in low status individuals but have little impact in high status individuals. However, there was a monolingual advantage on the TOL test of executive planning ability. Together, our findings run counter to the central assertion of the bilingual advantage account, that the process of multi-language acquisition confers a broad cognitive advantage in executive function. We discuss these findings in the context of SES as an important modulator in published studies advocating a bilingual cognitive advantage.

17.
PLoS One ; 13(10): e0205754, 2018.
Article En | MEDLINE | ID: mdl-30335801

In clinical neuropsychology the cognitive abilities of neurological patients are commonly estimated using well-established paper-based tests. Typically, scores on some tests remain relatively well preserved, whilst others exhibit a significant and disproportionate decline. Scores on those tests that measure preserved cognitive functions (so-called 'hold' tests) may be used to estimate premorbid abilities, including scores in non-hold tests that would have been expected prior to the onset of cognitive impairment. Many hold tests entail word reading, with each word being graded as correctly or incorrectly pronounced. Inevitably, such tests are likely to contain words that provide little or no diagnostic power (i.e., can be eliminated without negatively affecting prediction accuracy). In this paper, a genetic algorithm is developed and demonstrated, using n = 92 neurologically healthy participants, to identify optimal word subsets from the National Adult Reading Test that minimize the mean error in predicting the most widely used clinical measure of IQ and cognitive ability, the Wechsler Adult Intelligence Scale Fourth Edition IQ. In addition to requiring only 17-20 of the original 50 words (suggesting that this test could be revised to be up to 66% shorter) and minimizing mean prediction error, the algorithm increases the proportion of the variance in the predicted variable explained in comparison to using all words (from r2 = 0.46 to r2 = 0.61). In a clinical setting this would improve estimates of premorbid cognitive function and, if an abbreviated revision to this test were to be adopted, reduce the arduousness of the test for patients. The proposed method is evaluated with jackknifing and leave one out cross validation. The general approach may be used to optimize the relationship between any two psychological tests by finding the question subset in one test that minimizes the prediction error in a second test by training the genetic algorithm using data collected from participants upon whom both tests have been administered. This approach may also be used to develop new predictive tests, since it provides a method to identify an optimal subset of a set of candidate questions (for which empirical data have been collected) that maximizes prediction accuracy and the proportion of variance in the predicted variable that can be explained.


Cognitive Dysfunction/diagnosis , Models, Biological , Neuropsychology/methods , Reading , Wechsler Scales , Adult , Aged , Algorithms , Cognition , Female , Healthy Volunteers , Humans , Intelligence , Logistic Models , Male , Middle Aged , Predictive Value of Tests , Young Adult
18.
Neuropsychol Rehabil ; 28(6): 1019-1027, 2018 Sep.
Article En | MEDLINE | ID: mdl-27624393

Since publication in 1982, the 50-item National Adult Reading Test (NART; Nelson, 1982; NART-R; Nelson & Willison, 1991) has remained a widely adopted method for estimating premorbid intelligence both for clinical and research purposes. However, the NART has not been standardised against the most recent revisions of the Wechsler Adult Intelligence Scale (WAIS-III; Wechsler, 1997, and WAIS-IV; Wechsler, 2008). Our objective, therefore, was to produce reliable standardised estimates of WAIS-IV IQ from the NART. Ninety-two neurologically healthy British adults were assessed and regression equations calculated to produce population estimates of WAIS-IV full-scale IQ (FSIQ) and constituent index scores. Results showed strong NART/WAIS-IV FSIQ correlations with more moderate correlations observed between NART error and constituent index scores. FSIQ estimates were closely similar to the published WAIS and WAIS-R estimates at the high end of the distribution, but at the lower end were approximately equidistant from the highly discrepant WAIS (low) and WAIS-R (high) values. We conclude that the NART is likely to remain an important tool for estimating the impact of neurological damage on general cognitive ability. We advise caution in the use of older published WAIS and/or WAIS-R estimates for estimating premorbid WAIS-IV FSIQ, particularly for those with low NART scores.


Cognition/physiology , Intelligence Tests , Intelligence/physiology , Wechsler Scales/standards , Adolescent , Adult , Aged , Female , Humans , Male , Middle Aged , Neuropsychological Tests , Reference Values , Statistics as Topic , Young Adult
19.
Nurs Educ Perspect ; 37(4): 242-243, 2016.
Article En | MEDLINE | ID: mdl-27740588

A recent teaching and learning innovation using new technologies involves the use of quick response codes, which are read by smartphones and tablets. Integrating this technology as a teaching and learning strategy in nursing and midwifery education has been embraced by academics and students at a regional university.


Education, Nursing, Baccalaureate , Electronic Data Processing , Midwifery/education , Smartphone , Female , Humans , Learning , Pregnancy , Students, Nursing , Universities
20.
Acta Psychol (Amst) ; 170: 112-26, 2016 Oct.
Article En | MEDLINE | ID: mdl-27387874

Strong correlations between measures of fluid intelligence (or Spearman's g) and working memory are widely reported in the literature, but there is considerable controversy concerning the nature of underlying mechanisms driving this relationship. In the four experiments presented here we consider the role of response conflict and task complexity in the context of real-time task execution demands (Experiments 1-3) and also address recent evidence that g confers an advantage at the level of task conceptualisation rather than (or in addition to) task execution (Experiment 4). We observed increased sensitivity of measured fluid intelligence to task performance in the presence (vs. the absence) of response conflict, and this relationship remained when task complexity was reduced. Performance-g correlations were also observed in the absence of response conflict, but only in the context of high task complexity. Further, we present evidence that differences in conceptualisation or 'modelling' of task instructions prior to execution had an important mediating effect on observed correlations, but only when the task encompassed a strong element of response inhibition. Our results suggest that individual differences in ability reflect, in large part, variability in the efficiency with which the relational complexity of task constraints are held in mind. It follows that fluid intelligence may support successful task execution through the construction of effective action plans via optimal allocation of limited resources.


Concept Formation/physiology , Memory, Short-Term/physiology , Psychomotor Performance/physiology , Adult , Aged , Aging/psychology , Color Perception/physiology , Conflict, Psychological , Female , Form Perception/physiology , Humans , Inhibition, Psychological , Intelligence , Male , Middle Aged , Photic Stimulation
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