Differential contributions of set-shifting and monitoring to dual-task interference

It is commonly argued that complex behaviour is regulated by a number of "executive functions", which work to coordinate the operation of disparate cognitive systems in the service of an overall goal. However, the identity, roles, and interactions of specific putative executive functions remain contentious, even within widely accepted tests of executive function. The authors present two experiments that use dual-task interference to provide further support for multiple distinct executive functions and to establish the differential contributions of those functions in two relatively complex executive tasks-random generation and the Wisconsin Card Sorting Test. Results are interpreted in terms of process models of the complex executive tasks.     

Sequential dependencies in the Eriksen flanker task: A direct comparison of two competing accounts

In the conflict/control loop theory proposed by Botvinick, Braver, Barch, Carter, and Cohen (2001), conflict monitored in a trial leads to an increase in cognitive control on the subsequent trial. The critical data pattern supporting this assertion is the so-called Gratton effect—the decrease in flanker interference following incongruent trials—which was initially observed in the Eriksen flanker task. Recently, however, the validity of the idea that this pattern supports a general conflict/control mechanism has been questioned on the grounds that the Gratton effect is only observed with stimulus repetition. We present an experiment testing whether the Gratton effect reflects a stimulus-independent increase in cognitive control or stimulus-specific repetition priming. Although our results support the latter hypothesis, the priming effect is modulated by the congruency of the previous trial. We discuss a new mechanism through which monitored conflict is used to exert executive control by modulating stimulus-response associations.     

Delayed reconfiguration of a non-emotional task set through reactivation of an emotional task set in task switching: an ageing study

ABSTRACT

In our everyday life, we frequently switch between different tasks, a faculty that changes with age. However, it is still not understood how emotion impacts on age-related changes in task switching. Using faces with emotional and neutral expressions, Experiment 1 investigated younger (n?=?29; 18–38 years old) and older adults’ (n?=?32; 61–80 years old) ability to switch between an emotional and a non-emotional task (i.e. responding to the face's expression vs. age). In Experiment 2, younger and older adults also viewed emotional and neutral faces, but switched between two non-emotional tasks (i.e. responding to the face's age vs. gender). Data from Experiment 1 demonstrated that switching from an emotional to a non-emotional task was slower when the expression of the new face was emotional rather than neutral. This impairment was observed in both age groups. In contrast, Experiment 2 revealed that neither younger nor older adults were affected by block-wise irrelevant emotion when switching between two non-emotional tasks. Overall, the findings suggest that task-irrelevant emotion can impair task switching through reactivation of the competing emotional task set. They also suggest that this effect and the ability to shield task-switching performance from block-wise irrelevant emotion are preserved in ageing.     

Short-term memory after all: comment on Sederberg, Howard, and Kahana (2008)

P. B. Sederberg, M. W. Howard, and M. J. Kahana have proposed an updated version of the temporal-context model (TCM-A). In doing so, they accepted the challenge of developing a single-store model to account for the dissociations between short- and long-term recency effects that were reviewed by E. J. Davelaar, Y. Goshen-Gottstein, A. Ashkenazi, H. J. Haarmann, and M. Usher (2005). In this commentary, the authors argue that the success of TCM-A in addressing the dissociations is dependent not only on an episodic encoding matrix but--critically--also on its implicit use of a short-term memory store--albeit exponential rather than buffer-like. The authors also highlight some difficulties of TCM-A in accounting for these dissociations, and they argue that TCM-A fails to account for critical data--the presentation-rate effect--that dissociates exponential and buffer-like models.     

Phonological encoding in the lexical decision task

In lexical decision experiments, subjects have difficulty in responding NO to non-words which are pronounced exactly like English words (e.g. BRANE). This does not necessarily imply that access to a lexical entry ever occurs via a phonological recoding of a visually-presented word. The phonological recoding procedure might be so slow that when the letter string presented is a word, access to its lexical entry via a visual representation is always achieved before phonological recoding is completed. If prelexical phonological recodings are produced by using grapheme-phoneme correspondence rules, such recodings can only occur for words which conform to these rules (regular words), since applications of the rules to words which do not conform to the rules (exception words) produce incorrect phonological representations. In two experiments, it was found that time to achieve lexical access (as measured by YES latency in a lexical decision task) was equivalent for regular words and exception words. It was concluded that access to lexical entries in lexical decision experiments of this sort does not proceed by sometimes or always phonologically recoding visually-presented words.     

Variability and standardized test profiles in typically developing children and children with Williams Syndrome

Williams Syndrome (WS) is a developmental disorder, which due to its specific cognitive profile, has been of interest to multidisciplinary research in order to study the pathways between cognition, brain, and genes. Previous studies investigating individual performance on cognitive tasks have reported large variability within the WS cognitive profile, which has encouraged the investigation of WS subgroups. The current study compared the variability in performance scores on five verbal and non‐verbal standardized tests in 33 children with WS and in 33 typically developing (TD) children of a similar chronological age (CA). In contrast to previous studies, the current study did not find significant differences in variability in performance on British Picture Vocabulary scale, Test Reception of Grammar and Digit span Forward between WS and TD groups when CA was controlled for. However, there was significantly less variability in younger WS participants for performance scores on Pattern Construction compared to the TD group. In light of these results, methodological issues and the importance of taking CA into account in analyses will be discussed.     

Word identification: Imageability, semantics, and the content-functor distinction

It has often been suggested that different special-purpose mechanisms underlie the processing of content words and function words. The received view is that processing differences in various tasks arise because of differences between these word classes in terms of their semantic/syntactic function, despite the fact that these tasks often involve word processing in the absence of any sentence context. It is also well known that the ease with which a word arouses a sensory impression is often a good predictor of word-processing performance, yet the literature largely ignores the fact that, typically, imageability and word class are confounded factors. A series of three experiments shows that in the context of a Stroop task, the typical content-function word difference can be obtained, but that this word class difference disappears completely when the items are matched on the dimension of imageability. It is suggested that the processing of decontextualized content and function words does not necessarily engage distinct special purpose processing mechanisms. Implications for understanding previously published work on word class effects in other paradigms are briefly noted.