Task-switching costs without task-switching

Li, Xiangqian (2018) Task-switching costs without task-switching. PhD thesis, University of Glasgow.

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It has been suggested that task-switching costs can be eliminated if participants memorise all stimulus-response mappings thereby avoiding task-switching altogether (Dreisbach, Goschke & Haider, 2006, 2007; Dreisbach & Haider, 2008). This has been labelled the “Look-Up Table” (LUT) approach. It has also been suggested that the LUT approach could potentially explain why animals such as monkeys (Stoet & Snyder, 2003; Avdagic et al., 2013) and pigeons (Castro & Wasserman, 2016; Meier, Lea & McLaren 2016) were able to perform task-switching without showing any task-switching costs (Dreisbach, et al., 2006, 2007; Dreisbach & Haider, 2008; Forrest, Monsell & Mclaren, 2014). In a series of eight experiments the following two questions were addressed: (1) Why do some participants show significant task-switching costs even when they do not switch between tasks (e.g., Forrest, Monsell & Mclaren, 2014)? (2) Can the LUT approach explain the absence of task-switching costs? In an attempt to answer both questions different sources of human task-switching costs are investigated in eight behavioural experiments.
Chapter 1 provides an overview of different task-switching paradigms and accounts to explain task-switching costs. Chapter 2 summarises previous attempts to remove human task-switching costs. Evidence for the absence of task-switching costs in animals is also introduced. Following up on previous studies that suggested the LUT approach can explain the absence of task-switching costs, I conducted two task-switching experiments using visual tasks (i.e., colour task and shape task) with bivalent stimuli in an attempt to re-examine the conclusions of previous LUT studies (i.e., Dreisbach, et al., 2006, 2007; Dreisbach & Haider, 2008; Forrest, Monsell & Mclaren, 2014). The results in Chapter 2 indicate that human participants cannot always eliminate task-switching costs and do not always apply the LUT approach when the task-switching strategy is controlled.
Therefore, the experiments in Chapter 3 and 4 sought to ascertain the requirements for eliminating task-switching costs when using the LUT approach. The experiments in Chapter 3 applied visual tasks where each task had a different stimulus-set. Experiments in Chapter 4 applied two classical mathematical tasks (i.e., big/small task, odd/even task) and used Chinese numbers as stimuli. The results of the experiments in Chapters 3 and 4 suggest that human participants must be able to give the correct answer without processing task-relevant features from the stimuli in order to eliminate task-switching costs. In the experiment of Chapter 5 the cue-stimulus-response mappings from Experiments 2.1 and 2.2 were rearranged so that switching between conventional tasks and rules became impossible. The results suggest that task-relevant features can trigger interferences thereby causing “task-switching costs” even when participants do not switch between tasks.
In Chapter 7, I compare a modified interference account, introduced in Chapter 5, with the compound retrieval account (e.g., Logan & Schneider, 2010) and associative learning account (Forrest et al., 2014; Meier et al., 2016) in order to explain why human participants show task-switching costs even when they do not switch between tasks. I conclude that the modified interference account provides an alternative explanation. It has been proposed that only humans are affected by strong and long-lasting interference from previous trials during task-switching. As a consequence, this interference may explain why human participants consistently show task-switching costs whereas monkeys and pigeons show no task-switching costs.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Task-switching.
Subjects: B Philosophy. Psychology. Religion > BF Psychology
H Social Sciences > H Social Sciences (General)
Colleges/Schools: College of Science and Engineering > School of Psychology
Supervisor's Name: Lages, Dr. Martin
Date of Award: 2018
Depositing User: Mr Xiangqian Li
Unique ID: glathesis:2018-8962
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 19 Apr 2018 08:59
Last Modified: 08 May 2018 10:50
URI: https://theses.gla.ac.uk/id/eprint/8962

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