Asymmetric switch costs in numeral naming and number word reading: Implications for models of bilingual language production

One approach used to gain insight into the processes underlying bilingual language comprehension and production examines the costs that arise from switching languages. For unbalanced bilinguals, asymmetric switch costs are reported in speech production, where the switch cost for Ll is larger than the switch cost for L2, whereas, symmetric switch costs are reported in language comprehension tasks, where the cost of switching is the same for L1 and L2. Presently, it is unclear why asymmetric switch costs are observed in speech production, but not in language comprehension. Three experiments are reported that simultaneously examine methodological explanations of task related differences in the switch cost asymmetry and the predictions of three accounts of the switch cost asymmetry in speech production. The results of these experiments suggest that (1) the type of language task (comprehension vs. production) determines whether an asymmetric switch cost is observed and (2) at least some of the switch cost asymmetry arises within the language system

Task-specific effects of reward on task switching

Although cognitive control and reinforcement learning have been researched extensively over the last few decades, only recently have studies investigated their interrelationship. An important unanswered question concerns how the control system decides what task to execute and how vigorously to carry out the task once selected. Based on a recent theory of control formulated according to principles of hierarchical reinforcement learning, we asked whether rewards can affect top-down control over task performance at the level of task representation. Participants were rewarded for correctly performing only one of two tasks in a standard task-switching experiment. Reaction times and error rates were lower for the reinforced task compared to the non-reinforced task. Moreover, the switch cost in error rates for the non-reinforced task was significantly larger compared to the reinforced task, especially for trials in which the imperative stimulus afforded different responses for the two tasks, resulting in a "non-paradoxical" asymmetric switch cost. These findings suggest that reinforcement at the task level resulted in greater application of top-down control rather than in stronger stimulus-response pathways for the rewarded task

A domain-general monitoring account of language switching in recognition tasks : evidence for adaptive control

Language switching experience is assumed to have an effect on domain-general control abilities in bilinguals, but previous studies on the relationship between these two variables have generated mixed results. The present study investigated the effects of bilingual experiences on the interaction between language switching and domain-general control. Thirty-two Dutch-French bilingual young adults executed a bilingual categorisation task to assess their language switching abilities and a Simon task to assess domain-general control. The results show that global response times on the Simon task were correlated to the forward switch cost (from L1 to L2); moreover, interestingly, the forward switch cost was found to be related to recent language exposure but not to the age of second language acquisition. We suggest a monitoring account of language switching to integrate the first finding with previous studies and we interpret the second finding as support for the adaptive control hypothesis

Human task switching and the role of inhibitory processes : a computational modelling and empirical approach

Task switching is a behavioural paradigm within cognitive psychology that has been claimed to reflect the activity of high-level cognitive control processes. However, classic behavioural markers such as the (n-1) switch cost have also been shown to reflect a multitude of other cognitive processes. The n-2 repetition paradigm has proven more successful, with a behavioural measure (the n-2 repetition cost) agreed to be reflective of a cognitive inhibition mechanism (‘backward inhibition’). The present thesis develops computational models of task switching, including a backward inhibition model. The models are developed within the interactive-activation and competition (IAC) framework, as a development of an existing task switching model. Modelling is constrained by the general computational principles of the IAC framework and default parameter settings where these are shared with earlier models. The effect of specific novel parameter settings on behaviour is explored systematically. The backward inhibition model predicts a range of empirically observed behavioural phenomena including both n-1 switch and n-2 repetition costs, and the modulation of the n-2 repetition cost under certain circumstances, including the manipulation of intertrial intervals. A specific prediction of the model, the modulation of n-2 repetition costs according to switch direction when tasks are of different difficulties, is tested empirically, with results confirming and providing validation of the model. Finally, consideration is given to how such a backward inhibition model could be adapted to maximise performance benefits in different task switching contexts, via a process of parameter tuning

Governance Issues in the Principal-Agent Framework: Producing Cellulosic Ethanol in Michigan

This article analyzes the incentives and compensation problems faced by cellulosic ethanol producer and logging firms and the consequent impact on the organization of the wood based cellulosic ethanol industry in the US. The success of this relationship is central to setting up the biofuel industry in Michigan and in the US at large. The theoretical results indicate that specification contract under the principal-agent framework is of limited utility due to’ metering’ problem when the principal contracts with multiple agents for the supply of feedstock.. Alternative arrangements including JVs have the potential to provide close to first best solutions.Principal-Agent, Cellulosic Ethanol, Michigan, Multiple agents, Asymmetric Information, Agribusiness, Institutional and Behavioral Economics, Resource /Energy Economics and Policy, D82, D86, L23, L24, Q42,

Language and Math: What If We Have Two Separate Naming Systems?

Producción CientíficaThe role of language in numerical processing has traditionally been restricted to counting and exact arithmetic. Nevertheless, the impact that each of a bilinguals’ languages may have in core numerical representations has not been questioned until recently. What if the language in which math has been first acquired (LLmath) had a bigger impact in our math processing? Based on previous studies on language switching we hypothesize that balanced bilinguals would behave like unbalanced bilinguals when switching between the two codes for math. In order to address this question, we measured the brain activity with magneto encephalography (MEG) and source estimation analyses of 12 balanced Basque-Spanish speakers performing a task in which participants were unconscious of the switches between the two codes. The results show an asymmetric switch cost between the two codes for math, and that the brain areas responsible for these switches are similar to those thought to belong to a general task switching mechanism. This implies that the dominances for math and language could run separately from the general language dominance.Departamento de Cultura y Política Lingüística del Gobierno Vasco (grant PRE_992)Junta de Castilla y León - FEDER (Project VA009P17

Task Switching Over the Lifespan

People often switch from one goal to another, in response to changing environmental demands. Task switching affords flexibility, but at a price. A robust switch cost ensues, whereby individuals are slower and less accurate when switching between tasks than when repeating tasks. The current dissertation investigated the factors that contribute to a switch cost, using an exceptionally large sample of over 25,000 individuals (ages 10 to over 65) collected online. Switch costs are interpreted as the duration of psychological processes that are recruited to shift between tasks. In Study 1, shifting a task took 576 ms (or 108%) longer than performing a single task. Shifting tasks resulted in a 34% immediate decrease in productivity. An additional 74% long-term decrease in productivity occurred from maintaining readiness for a shift, and for using a cue to select a task, both of which occur even without an actual shift taking place. The results show that the seemingly simple switch cost involves multiple processes. Understanding these processes is crucial to interpret how flexibility varies with age. In Study 2A, task switching process developed until adulthood and then declined, similar to general cognitive ability. However, each process changed differently with age. Findings show that decline is not simply development in reverse: The rate of decline in mid to late adulthood was up to 20 times slower than the rapid development in adolescence; Middle-aged adults were slower than young adults, but as accurate; They maintained less advance readiness but used contextual cues as well as their younger counterparts. In Study 2B, the effects of age were replicated in an independent sample using identical methodology. These findings highlight the usefulness of web-based data collection, effect size estimation, and segmented regression techniques