Switch costs and related concepts

1. Switch costs and related concepts Christina Surdy

2. Task set: the cognitive representation of task requirements (aka stimulus-response mapping) Taskset reconfiguration (TSR): The partial retrieval of task ‘rules’ involved in task preparation– mental gear changing Mixed task blocks: fixed task sequences in which task switches every trial (e.g. ABABAB) Single task blocks: require only one task (e.g. AAA or BBB) Switch cost: difference in performance (RT) and accuracy (errors) between a repeated task (AA) and a task switch (AB) Components of switch costs: • Preparatory component • Residual component (aka residual switch cost) • Dissipating component Tasks typically used: • word reading • colour and object naming • categorizing digits (magnitude or parity) • categorizing letters (vowels or consonants) • categorizing words (living/non-living) • responding according to the location of a stimulus

3. Response-Stimulus Interval (RSI): the time interval from the completion of response in one trial to the presentation of the following stimulus. Cue-Stimulus Interval (CSI): amount of time participants have to prepare before a trial Response-Cue Interval (RCI):passive waiting period between two trials when participants do not know which task is next. Pure alternation design (Jersild, 1927): Switch costs are derived by comparing performance on blocks of trials in which participants are instructed to continually alternate between tasks from trial to trial (i.e ABABAB), with performance on blocks in which they complete the same task on all trials (i.e. AAA and BBB) Mixed block design: Repeated presentations of the same task and shifts between tasks are mixed within the same block (e.g. Alternating Runs, random mix, task-cuing, intermittent instruction)

4. Jersild’s(1927) compared performance in alternating trial blocks (ABABAB) with performance in single/pure blocks (AAA or BBB)via list presentation technique. • Calculated “shift loss” (switch cost). • Add 6 and subtract 3 vs. name antonym and subtract 3 • Interpreted switch cost as an index of the extra difficulty associated with reconfiguring a task-set. Spector & Biederman (1976)  revived Jersild(1927) • No cost or benefit when stimuli presented on cards • Large switch cost when adding 3 and subtracting 3 • Switch costs are determined by the extent to which the stimulus provides a retrieval cue for the appropriate/current task to be performed. Allport et al. (1994)  two ensembles of stimuli • Stroop colour words and digits • smaller switch costs when the participants switched between task ensembles than when they switched between tasks withinensembles • larger switch costs for word reading (‘automatic’ task) than for colour naming (‘controlled’ task) • Task Set Inertia hypothesis (aka proactive interference)

5. Rogers & Monsell (1995)  alternating runs paradigm • compare switch and non-switch trials trials in the same block (Participants know to switch tasks every “nth” trial) • if n = 2, sequence of trials = AABBAABB • Classify number (odd/even) or letter (consonant/vowel) • Large switch cost remains when RSI extended from 600ms to 1200ms • Large switch costs when RSI was unpredictable, but smaller costs when RSI was held constant • Switch costs interpreted in terms of task-set reconfiguration. Grange & Houghton(2010) Cue Switch Costs  target detection paradigm • Two cues are used per task (enables the separation of task switch costs from cue-switch costs) • Cue switch costs measured by comparing performance on cue-switch trials with cue-repetition trials (in neither case does the task switch). • Target (e.g. an oval) is determined by one of two valid cues (either a word that describes its distinctive property or ashape that depicts its visual property) • Cue-switch costs arise from active control processes that form a WM representation

6. Residual switch cost Residual switch cost: switch costs that remain after a participant has had time to prepare for the shift of tasks • Residual switch costs result from additional processes insensitive to preparation • Exogenous and endogenous components of reconfiguration (Rogers & Monsell, 1995) • Retrieval of relevant task goals and activation of relevant task rules (Rubinstein et al., 2001) • Task set inertia (Allport et al., 1994) • Long term priming (Waszak et al., 2003) 2. Residual switch costs result from uncompleted processed during preparation • Failure to engage theory (De Jong, 2000) • Cue-retrieval hypothesis (Logan & Bundesen, 2003)

7. Multitasking Individual differences in multitasking include: • Perceptual speed • Motivation • Neuroticism • Preference to multitask? • Multitasking ability:operationalized as a task-dependent metric of performance when the difficulty of a set of tasks is at baseline. • Multitasking adaptability: the capacity to adapt to changing task constraint relative to baseline performance (e.g. how performance is affected if the difficulty of one or more tasks changes, or if a new task is introduced, or if a task is dropped). • Scholastic aptitude and working memory shown to predict general multitasking ability (at baseline). • Spatial manipulation and working memory shown to predict multitasking adaptability. • Relation between multitasking and performance depends upon the metric used (Adler & Benbunan-Fich, 2012). • Strong correlation between number of switches and Sudoku ease.