The synergy of working memory and inhibitory control: behavioral, pharmacological and neural functional evidences

Concomitant deficits in working memory and behavioral inhibition in several psychiatric disorders like attention-deficit/hyperactivity disorder, addiction or mania, suggest that common brain mechanisms may underlie their etiologies. Based on the theoretical assumption that a continuum exists between health and mental disorders, we explored the relationship between working memory and inhibition in healthy individuals, through spontaneous inter individual differences in behavior, and tested the hypothesis of a functional link through the fronto-striatal dopaminergic system. Rats were classified into three groups, showing good, intermediate and poor working memory and were compared for their inhibitory abilities. These two functions were simultaneously modulated by a dose-effect of d-amphetamine and in situ hybridization was used to quantify dopaminergic receptor (RD1) mRNAs in prefrontal cortex and striatal areas. A functional relationship between working memory and inhibition abilities was revealed. Both functions were similarly modulated by d-amphetamine according to an inverted-U shaped relationship and depending on initial individual performances. D-amphetamine selectively improved working memory and inhibition of poor and intermediate performers at low doses whereas it impaired both processes in good performers at a higher dose. D1 receptors were less expressed in prelimbic, infralimbic and anterior cingulate cortices of good compared to intermediate and poor performers, whereas no difference was observed between groups in striatal areas. The synergy of working memory and inhibitory abilities, observed in both healthy and psychiatric populations, may originate from endogenous variability in dopaminergic prefrontal cortex activity. Such findings confirm the validity of a dimensional approach, based on the concept of continuity between health and mental disorders for identifying endophenotypes of mental disorders.     

Reconnecting cognition in the lab and cognition in real life: The role of compensatory social and motivational factors in explaining how cognition ages in the wild

The papers in this Special Issue compellingly show that older adults' everyday cognitive life is governed not by the decline in elementary cognitive processes as measured in the lab, but by a multitude of compensatory mechanisms, most of which are of the social/motivational variety. Much of this compensatory behavior can be elicited with no or only little experimental prodding, underscoring the self-organizing or self-initiated nature of this type of behavior, even in advanced old age. We suggest that the study of compensation and the orchestration of cognitive, social, and motivational compensatory mechanisms in effective and healthy aging provides a meaningful challenge to traditional ways of examining developmental changes in cognitive performance.     

Information retrieval with semantic memory model

Psycholinguistic theories of semantic memory form the basis of understanding of natural language concepts. These theories are used here as an inspiration for implementing a computational model of semantic memory in the form of semantic network. Combining this network with a vector-based object-relation-feature value representation of concepts that includes also weights for confidence and support, allows for recognition of concepts by referring to their features, enabling a semantic search algorithm. This algorithm has been used for word games, in particular the 20-question game in which the program tries to guess a concept that a human player thinks about. The game facilitates lexical knowledge validation and acquisition through the interaction with humans via supervised dialog templates. The elementary linguistic competencies of the proposed model have been evaluated assessing how well it can represent the meaning of linguistic concepts. To study properties of information retrieval based on this type of semantic representation in contexts derived from on-going dialogs experiments in limited domains have been performed. Several similarity measures have been used to compare the completeness of knowledge retrieved automatically and corrected through active dialogs to a “golden standard”. Comparison of semantic search with human performance has been made in a series of 20-question games. On average results achieved by human players were better than those obtained by semantic search, but not by a wide margin.     

Bias in self-motion perceived speed can enhance episodic memory

Prior experiences of a stimulus facilitate reprocessing of that stimulus on a subsequent occasion. This relative ease and speed with which information is processed is defined as fluency and can constitute a basis for memory judgment. Fluency can also be manipulated on line by perceptual bias (e.g., levels of noise), leading to an increase in recognition for items processed more fluently (e.g., items with less noise). Previous experiments using Remember-Know paradigm have shown an impact of perceptual fluency only on familiarity and not on recollection. Recent episodic memory models have postulated a strong link between episodic memory and spatial processes, especially with egocentric updating (Gomez et al. in Acta Psychol 132(3):221-227, 2009). The present experiment was conducted to determine whether self-motion fluency affects recognition performance and particularly has an impact on "Remember" responses. Thirty participants learned a 4-min path movie and then had to recognize among short paths if they were part of the learned path, followed by a Remember-Know procedure for recognized items. Self-motion fluency was manipulated with the presence of nimble acceleration applied on a small part of the recognition paths. Results show that the presence of a self-motion fluency increases significantly the proportion of remember responses solely on learned paths. This study spotlights for the first time a specific fluency effect on recollection and indicates an implication of egocentric-updating processing in episodic memory retrieval.     

Development of a Facebook Addiction Scale

The Bergen Facebook Addiction Scale (BFAS), initially a pool of 18 items, three reflecting each of the six core elements of addiction (salience, mood modification, tolerance, withdrawal, conflict, and relapse), was constructed and administered to 423 students together with several other standardized self-report scales (Addictive Tendencies Scale, Online Sociability Scale, Facebook Attitude Scale, NEO-FFI, BIS/BAS scales, and Sleep questions). That item within each of the six addiction elements with the highest corrected item-total correlation was retained in the final scale. The factor structure of the scale was good (RMSEA = .046, CFI = .99) and coefficient alpha was .83. The 3-week test-retest reliability coefficient was .82. The scores converged with scores for other scales of Facebook activity. Also, they were positively related to Neuroticism and Extraversion, and negatively related to Conscientiousness. High scores on the new scale were associated with delayed bedtimes and rising times.     

Development of a work addiction scale

Andreassen, C. S., Griffiths, M. D., Hetland, J. & Pallesen, S. (2012). Development of a work addiction scale. Scandinavian Journal of Psychology 53, 265–272. Research into excessive work has gained increasing attention over the last 20 years. Terms such as “workaholism,”“work addiction” and “excessive work” have been used interchangeably. Given the increase in empirical research, this study presents the development of the Bergen Work Addiction Scale (BWAS), a new psychometrically validated scale for the assessment of work addiction. A pool of 14 items, with two reflecting each of seven core elements of addiction (i.e., salience, mood modification, tolerance, withdrawal, conflict, relapse, and problems) was initially constructed. The items were then administered to two samples, one recruited by a web survey following a television broadcast about workaholism (n = 11,769) and one comprising participants in the second wave of a longitudinal internet‐based survey about working life (n = 368). The items with the highest corrected item‐total correlation from within each of the seven addiction elements were retained in the final scale. The assumed one‐factor solution of the refined seven‐item scale was acceptable (root mean square error of approximation = 0.077, Comparative Fit Index = 0.96, Tucker‐Lewis Index = 0.95) and the internal reliability of the two samples were 0.84 and 0.80, respectively. The scores of the BWAS converged with scores on other workaholism scales, except for a Work Enjoyment subscale. A suggested cut‐off for categorization of workaholics showed good discriminative ability in terms of working hours, leadership position, and subjective health complaints. It is concluded that the BWAS has good psychometric properties.     

Asymmetric switch-costs and ERPs reveal facial identity dominance over expression

Previous studies on face processing have revealed an asymmetric overlap between identity and expression, as identity is processed irrespective of expression while expression processing partly depends on identity. To investigate whether this relative interaction is caused by dominance of identity over expression, participants performed familiarity and expression judgments during task switching. This paradigm reveals task-set dominance with a paradoxical asymmetric switch-cost (i.e., greater difference between switch and repeat trials when switching toward the dominant task). Event-related potentials (ERPs) were recorded to find the neural signature of the asymmetric cost. As expected, greater switch-cost was shown in the familiarity task with respect to response times, indicating its dominance over the expression task. Moreover, a left-sided ERP correlate of this effect was observed at the level of the frontal N2 component, interpreted as an index of modulations in endogenous executive control. Altogether, these results confirm the overlap between identity and expression during face processing and further indicate their relative dominance.     

Safety behavior can hamper the extinction of fear of movement-related pain: An experimental investigation in healthy participants

Excessive fear of movement-related pain (FMRP), and its associated avoidance behavior, is considered a major risk factor for disability in chronic musculoskeletal pain. The current study aimed to investigate whether engaging in safety behavior, conceptualized as an avoidance response, hampers the extinction of FMRP. In a differential conditioning paradigm, we used joystick movements as conditioned stimuli (CSs) and a painful electrocutaneous stimulus as the unconditioned stimulus (US). In the Safety group, participants received the opportunity to avoid the pain-US by pressing a safety button during the extinction phase, whereas in the Control group, this option was not included. In a subsequent test phase, this safety button was no longer available. In two experiments, results demonstrate successful acquisition and extinction. Retrospective FMRP ratings in both experiments revealed a return of fear of pain in the test phase in the Safety group, but not in the Control group. In Experiment 1, mean eyeblink startle reflex amplitudes partly corroborated the self-report findings on fear of pain. The present results suggest that performing safety behavior during cognitive-behavioral interventions, i.e., exposure, might increase the risk of a return of FMRP.     

Evidence for multiple routes in learning to read

We describe a multiple-route model of reading development in which coarse-grained orthographic processing plays a key role in optimizing access to semantics via whole-word orthographic representations. This forms part of the direct orthographic route that gradually replaces phonological recoding during the initial phases of reading acquisition. The model predicts distinct developmental trajectories for pseudo-homophone and transposed-letter effects - two benchmark phenomena associated with phonological recoding and coarse-grained orthographic processing, respectively. Pseudo-homophone effects should decrease over the first years of reading acquisition, whereas transposed-letter effects should initially increase. These predictions were tested in a lexical decision task with 334 children in grades 1-5, and 29 skilled adult readers. In line with the predictions, we found that the pseudo-homophone effect diminished as reading level increased, whereas the transposed-letter effect first increased and then diminished.     

How to say "no" to a nonword: a leaky competing accumulator model of lexical decision

We describe a leaky competing accumulator (LCA) model of the lexical decision task that can be used as a response/decision module for any computational model of word recognition. The LCA model uses evidence for a word, operationalized as some measure of lexical activity, as input to the YES decision node. Input to the NO decision node is simply a constant value minus evidence for a word. In this way, evidence for a nonword is a function of time from stimulus onset (as in standard deadline models) modulated by lexical activity via the competitive dynamics of the LCA. We propose a simple mechanism for determining the value of this constant online during the first trials of a lexical decision experiment, such that the model can rapidly optimize speed and accuracy in discriminating words from nonwords. Further optimization is achieved via trial-by-trial adjustments in response criteria as a function of task demands and list context. We show that the LCA model can simulate mean response times and response distributions for correct and incorrect YES and NO decisions for a number of benchmark experiments that have been shown to be fatal for deadline models of lexical decision. Finally, using lexical activity calculated by a computational model of word recognition as input to the LCA decision module, we provide the first item-level simulation of both word and nonword responses in a large-scale database.