Rethinking volitional control over task choice in multitask environments: Use of a stimulus set selection strategy in voluntary task switching

Under conditions of volitional control in multitask environments, subjects may engage in a variety of strategies to guide task selection. The current research examines whether subjects may sometimes use a top-down control strategy of selecting a task-irrelevant stimulus dimension, such as location, to guide task selection. We term this approach a stimulus set selection strategy. Using a voluntary task switching procedure, subjects voluntarily switched between categorizing letter and number stimuli that appeared in two, four, or eight possible target locations. Effects of stimulus availability, manipulated by varying the stimulus onset asynchrony between the two target stimuli, and location repetition were analysed to assess the use of a stimulus set selection strategy. Considered across position condition, Experiment 1 showed effects of both stimulus availability and location repetition on task choice suggesting that only in the 2-position condition, where selection based on location always results in a target at the selected location, subjects may have been using a stimulus set selection strategy on some trials. Experiment 2 replicated and extended these findings in a visually more cluttered environment. These results indicate that, contrary to current models of task selection in voluntary task switching, the top-down control of task selection may occur in the absence of the formation of an intention to perform a particular task.     

No-go trials can modulate switch cost by interfering with effects of task preparation

It has recently been shown that the cost associated with switching tasks is eliminated following ‘no-go’ trials, in which response selection is not completed, suggesting that the switch cost depends on response selection. However, no-go trials may also affect switch costs by interfering with the effects of task preparation that precede response selection. To test this hypothesis we evaluated switch costs following standard go trials with those following two types of non-response trials: no-go trials, for which a stimulus is presented that indicates no response should be made (Experiment 1); and cue-only trials in which no stimulus is presented following the task cue (Experiment 2). We hypothesized that eliminating no-go stimuli would reveal effects of task preparation on the switch cost in cue-only trials. We found no switch cost following no-go trials (Experiment 1), but a reliable switch cost in cue-only trials (i.e., when no-go stimuli were removed; Experiment 2). We conclude that no-go trials can modulate the switch cost, independent of their effect on response selection, by interfering with task preparation, and that the effects of task preparation on switch cost are more directly assessed by cue-only trials.     

The mental effort requirement of cumulative rehearsal: A developmental study

Three experiments were conducted examining the relationship between the mental effort requirement of cumulative rehearsal and spontaneous utilization of the strategy by children. Mental effort was assessed by measuring the interference produced by cumulative rehearsal with a simultaneously performed secondary task (finger-tapping). It was found in Experiment 1 that second- and third-grade children experienced significantly more finger-tapping interference during instructed cumulative rehearsal than did sixth-grade children, an effect which, Experiment 2 demonstrated, could not be attributed simply to developmental differences in time-sharing performance. In Experiment 3 it was found that, for children in grades 2 through 5, rehearsal set size during spontaneous rehearsal was negatively correlated with amount of finger-tapping interference during instructed cumulative rehearsal, suggesting that spontaneous use of a cumulative rehearsal strategy was negatively correlated with the mental effort requirement of strategy use. These findings support the view that the mental effort requirement of strategy use may influence children's strategy selection on memory tasks.     

Controlled forgetting in the retarded

Three experiments investigated selective rehearsal by retardates in a serial memory task which was an adaptation of Bjork's (1970) paradigm involving instructions to forget a subset of the material presented. Since previous research indicated that retarded children do not selectively rehearse, and since Bjork's paradigm requires the use of a selective rehearsal strategy, it seemed likely that retardates would fail in this task. Experiment 1 showed that retardates could perform this task, and there was substantial evidence for cumulative rehearsal. The possibility of an averaging artifact in the data of Expt 1 was eliminated in Expt 2 by showing evidence of primacy and facilitation due to the forget instruction for individual Ss. Experiment 3 indicated that the facilitation due to the forget instruction was likely due to the effective use of a selective rehearsal strategy. These results contrast with other findings of no rehearsal in retarded children. It is suggested that response biases may be involved in previous studies of rehearsal.     

Overriding stimulus-driven attentional capture

Theeuwes (1992) found a distracting effect of irrelevant-dimension singletons in a task involving search for a known target. He argued from this that selectivity is determined solely by stimulus salience; the parallel stage of visual processing cannot provide top-down guidance to the attentive stage sufficient to permit completely selective use of task-relevant information. We argue that in the task used by Theeuwes, subjects may have adopted the strategy of searching for an odd form even though the specific target form was known. In Experiment 1, we replicated Theeuwes’s findings. Search for a circle target among diamond nontargets was disrupted by the presence of a diamond nontarget that was uniquely colored. In two subsequent experiments, we discouraged the singleton detection strategy, forcing subjects to search for the target feature. There was no distracting effect of a color singleton in these experiments, even with displays physically identical to those of Experiment 1, demonstrating that top-down selectivity is indeed possible during visual search. We conclude that goal-directed selection of a specific known featural identity may override stimulus-driven capture by salient featural singletons.     

The effect of cue-familiarity, cue-distinctiveness, and retention interval on prospective remembering

Five experiments investigated the effects of cue familiarity, cue distinctiveness, and retention interval on prospective remembering. Results showed that (1) performance in a prospective memory task is facilitated when the cue is unfamiliar and/or distinctive; and (2) it is impaired by 3-minutes' delay between the instructions and the task (Experiment 1). A beneficial effect of distinctiveness was also found when perceptual rather than semantic distinctiveness was tested (Experiment 2). Experiments 3 and 4 ruled out the hypotheses that “unfulfilled expectancy” of an event (i.e. non-appearance of the cue during training) (Experiment 3), or some sort of “habituation” in the target context (Experiment 4), may have caused the low performance observed in the delayed conditions. Finally, results from Experiment 5 showed that delay negatively affected prospective remembering when it was filled with either a demanding interpolated activity (practice in a STM task) or an undemanding motoric activity (repetitive hands movements). Unfilled delay and an undemanding verbal activity (counting) were found not to affect prospective memory. Implications for the mechanisms underlying prospective remembering are discussed.     

Selection of strategies for narrowing choice options: Antecedents and consequences

This study investigates the antecedents (task and decision maker characteristics) and consequences (set size and decision quality) of prescreening strategy selection. In Experiment 1 we investigated which strategy, inclusion or exclusion, is more natural for narrowing choices in tasks with a single correct answer; about 70% of the participants selected exclusion. Experiment 2 directly contrasted correct answer tasks with personal judgment tasks, using the same foils for the two tasks. Participants were more likely to use exclusion for items with a correct answer than for personal judgments. In Experiment 3, participants could choose different strategies for different items and rated the difficulty of each item. The greater the perceived difficulty of an item, the more likely participants were to choose an exclusion strategy. In all three experiments exclusion led to larger set sizes, across task type and experimental design. There were no differences in decision quality as a function of strategy selection after correcting for set size. Individual differences based on personality inventories were not found to be good predictors of strategy selection, but had moderate effects on set size for personal judgment tasks. Results are discussed in terms of a status quo bias for adding or deleting options from an initial reference frame.     

Sensible reasoning in two tasks: Rule discovery and hypothesis evaluation

The hypothesis testing skills of undergraduates were measured in two tasks: the 2-4-6 rule discovery task in which students generate and assess hypotheses, and a hypothesis evaluation task, which requires only the assessment of hypotheses. The results of Experiments 1 and 2 show that the students consistently employed a disconfirmation strategy when assessing hypotheses, but employed a counterfactual inference strategy when they also were required to generate the hypotheses. The results of Experiment 3 suggest that the selection of the hypothesis testing strategy reflected a balance between the logical requirements of the task and the desirability of possible outcomes. Taken together, the findings support a more consistent picture of human rationality across tasks, and suggest alternatives to accounts of confirmation bias.     

Mixing costs in task shifting reflect sequential processing stages in a multicomponent task

We investigated the hypothesis that mixing costs intask shifting reflect th e sequential selection of task components (e.g., stimulus categories) during task execution. This proposition was supported by Hübner, Futterer, and Steinhauser (2001), who showed that the amount of mixing costsdepends on the number of mixed task components (e.g., stimulus level and judgment). However, their results could also be explained by a task set selection account, because task components and task sets were confounded. In Experiments 1 and 2, we compared conditions in which either the number of task sets varied and the number of mixed task components was constant or vice versa. Only the number of mixed task components was predictive for the mixing costs. In Experiment 3, we replicated the additivity of mixing costs from level a ndjudgment mixing. Our results suggest thatthe mixingcosts reflect a selection strategy in which interference is reduced in a stepwise manner.     

Social salience does not transfer to oculomotor visual search

ABSTRACT

Evidence suggests that socially relevant information, such as self-referential information, leads to perceptual prioritization that is considered to be similar to prioritization based on physical stimulus salience. The current study used an oculomotor visual search paradigm to investigate whether self-prioritization affects visual selection early in time, akin to physical salience, or later in time, where it would relate to processing of top-down strategies. We report three experiments. Prior to each experiment, observers first performed a manual line-label matching task where they were asked to form associations between two orientation lines (right-tilted and left-tilted) and two labels (“you” and “stranger”). Participants then had to make a speeded eye-movement to one of the two lines without any task instructions (Experiment 1), to a dot probe target located on one of the two lines (Experiment 2), or to the line that was validly cued by its associated label (Experiment 3). We replicate previous findings with the manual stimulus-matching task. However, we did not find any evidence for increased salience of the self-relevant “you” stimulus during visual search, nor did we observe any self-prioritization due to later goal-driven or strategic processing. We argue that self-prioritization does not affect overt visual selection. The results suggest that the effects found in the manual matching task are unlikely to reflect self-prioritization during perceptual processing but might rather act on higher-level processing related to recognition or decision-making.     

Information access in a dual-task context: testing a model of optimal strategy selection

Pilots were required to access information from a hierarchical aviation database by navigating under single-task conditions (Experiment 1) and when this task was time-shared with an altitude-monitoring task of varying bandwidth and priority (Experiment 2). In dual-task conditions, pilots had 2 viewports available, 1 always used for the information task and the other to be allocated to either task. Dual-task strategy, inferred from the decision of which task to allocate to the 2nd viewport, revealed that allocation was generally biased in favor of the monitoring task and was only partly sensitive to the difficulty of the 2 tasks and their relative priorities. Some dominant sources of navigational difficulties failed to adaptively influence selection strategy. The implications of the results are to provide tools for jumping to the top of the database, to provide 2 viewports into the common database, and to provide training as to the optimum viewport management strategy in a multitask environment.     

Blur detection is unaffected by cognitive load

Blur detection is affected by retinal eccentricity, but is it also affected by attentional resources? Research showing effects of selective attention on acuity and contrast sensitivity suggests that allocating attention should increase blur detection. However, research showing that blur affects selection of saccade targets suggests that blur detection may be pre-attentive. To investigate this question, we carried out experiments in which viewers detected blur in real-world scenes under varying levels of cognitive load manipulated by the N-back task. We used adaptive threshold estimation to measure blur detection thresholds at 0°, 3°, 6°, and 9° eccentricity. Participants carried out blur detection as a single task, a single task with to-be-ignored letters, or an N-back task with four levels of cognitive load (0, 1, 2, or 3-back). In Experiment 1, blur was presented gaze-contingently for occasional single eye fixations while participants viewed scenes in preparation for an easy picture recognition memory task, and the N-back stimuli were presented auditorily. The results for three participants showed a large effect of retinal eccentricity on blur thresholds, significant effects of N-back level on N-back performance, scene recognition memory, and gaze dispersion, but no effect of N-back level on blur thresholds. In Experiment 2, we replicated Experiment 1 but presented the images tachistoscopically for 200 ms (half with, half without blur), to determine whether gaze-contingent blur presentation in Experiment 1 had produced attentional capture by blur onset during a fixation, thus eliminating any effect of cognitive load on blur detection. The results with three new participants replicated those of Experiment 1, indicating that the use of gaze-contingent blur presentation could not explain the lack of effect of cognitive load on blur detection. Thus, apparently blur detection in real-world scene images is unaffected by attentional resources, as manipulated by the cognitive load produced by the N-back task.     

The role of space and time in object-based visual search

Recently we have provided evidence that observers more readily select a target from a visual search display if the motion trajectory of the display object suggests that the observer has dealt with it before. Here we test the prediction that this object-based memory effect on search breaks down if the spatiotemporal trajectory is disrupted. Observers searched a display for a target shape among multiple distractors. The entire search display then passed behind an occluder and reemerged in either the same or a different configuration. Experiment 1 shows that the same-object benefit for selection disappears whenever a spatial disruption is involved, but that it may survive a brief temporal disruption. Experiment 2 shows that with sufficiently long gaps, a temporal disruption also destroys the same-object benefit for selective attention. Experiment 3 demonstrates that the same-object effect is even stronger when there only is a very small probability that the target can be found at the same location as before. This also made the task sensitive to brief temporal disruptions. We conclude that a coherent spatiotemporal history of a display object supports the selection of its relevant subregions.     

Social influence on metacognitive evaluations: The power of nonverbal cues

Metacognitive evaluations refer to the processes by which people assess their own cognitive operations with respect to their current goal. Little is known about whether this process is susceptible to social influence. Here we investigate whether nonverbal social signals spontaneously influence metacognitive evaluations. Participants performed a two-alternative forced-choice task, which was followed by a face randomly gazing towards or away from the response chosen by the participant. Participants then provided a metacognitive evaluation of their response by rating their confidence in their answer. In Experiment 1, the participants were told that the gaze direction was irrelevant to the task purpose and were advised to ignore it. The results revealed an effect of implicit social information on confidence ratings even though the gaze direction was random and therefore unreliable for task purposes. In addition, nonsocial cues (car) did not elicit this effect. In Experiment 2, the participants were led to believe that cue direction (face or car) reflected a previous participant's response to the same question—that is, the social information provided by the cue was made explicit, yet still objectively unreliable for the task. The results showed a similar social influence on confidence ratings, observed with both cues (car and face) but with an increased magnitude relative to Experiment 1. We additionally showed in Experiment 2 that social information impaired metacognitive accuracy. Together our results strongly suggest an involuntary susceptibility of metacognitive evaluations to nonverbal social information, even when it is implicit (Experiment 1) and unreliable (Experiments 1 and 2).     

Response retrieval in a go/no-go priming-of-popout task

Priming of popout is the finding that singleton search is faster when features of a target and of nontargets are repeated across trials than when the features switch. Theoretical accounts suggest that intertrial repetition influences perceptual and attentional selection processes, episodic retrieval processes, or both. The present study combined a popout search task with a go/no-go task. In Experiment 1, the nontarget distractors in each display carried the go/no-go feature, and in Experiment 2, the texture of all items carried the go/no-go feature. Results showed that the go/no-go task moderated the intertrial repetition effects. In Experiment 1, the target color elicited retrieval of the preceding distractor color and associated no-go response, resulting in larger interference effects. In Experiment 2, the target color elicited retrieval of the preceding target color and no-go response, resulting in reduced facilitation effects. Additional results from both experiments showed that the colors in a search display also influenced target selection on the following trial. Taken together, the results of both experiments suggest that intertrial repetition influences both early selection and postselection retrieval processes.     

社会评价影响错误后调整效应

现有研究主要采用结果评价或结果反馈的方式考察评价对错误后调整效应的影响,但是任务前的社会评价怎样影响错误后调整效应尚不清楚。本研究采用社会评价任务,以错误后反应时和错误后正确率为指标,在两个实验中考察正性和负性评价对错误后调整效应的影响。结果发现,实验1和实验2中正性和负性评价条件下错误后减慢效应差异均不显著,说明正性和负性评价对错误后调整的作用是一致的,且不受实验任务的影响。在实验1中通过和无评价条件比较发现,评价条件下的正确后反应显著慢于无评价条件,但是评价条件下的错误后反应与无评价条件无差异,说明社会评价加速了个体错误后调整。而且在实验2中发现高低自我效能组个体错误后调整效应差异不显著,说明当前结果不受个体自我效能感的影响。因此,当前研究说明任务前的社会评价促进了个体错误后行为调整,但是错误后调整效应不受社会评价效价的影响。     

Unconscious biases in task choices depend on conscious expectations

Recent studies highlight the influence of non-conscious information on task-set selection. However, it has not yet been tested whether this influence depends on conscious settings, as some theoretical models propose. In a series of three experiments, we explored whether non-conscious abstract cues could bias choices between a semantic and a perceptual task. In Experiment 1, we observed a non-conscious influence on task-set selection even when perceptual priming and cue-target compound confounds did not apply. Experiments 2 and 3 showed that, under restrictive conditions of visibility, cues only biased task selection when the conscious task-setting mindset led participants to search for information during the time period of the cue. However, this conscious strategy did not modulate the effect found when a subjective measure of consciousness was used. Altogether, our results show that the configuration of the conscious mindset determines the potential bias of non-conscious information on task-set selection.     

The role of response selection for inhibition of task sets in task shifting

Response selection in task shifting was explored using a go/no-go methodology. The no-go signal occurred unpredictably with stimulus onset so that all trials required task preparation but only go trials required response selection. Experiment 1 showed that shift costs were absent after no-go trials, indicating that response processes are crucial for shift costs. In Experiment 2, backward inhibition was absent after no-go trials. Experiments 3 and 4 demonstrated that response selection, rather than execution, causes backward inhibition. All 4 experiments showed effects of preparation time in go trials, suggesting that advance preparation must have also occurred in no-go trials. The authors concluded that inhibition of irrelevant task sets arises only at response selection and that residual shift costs reflect such persisting inhibition.     

A quantitative model of optimal data selection in Wason's selection task.

The optimal data selection model proposed by Oaksford and Chater (1994) successfully formalized Wason's selection task (Wason, 1966). The model, however, involved some questionable assumptions and was also not sufficient as a model of the task because it could not provide quantitative predictions of the card selection frequencies. In this paper, the model was revised to provide quantitative fits to the data. The model can predict the selection frequencies of cards based on a selection tendency function (STF), or conversely, it enables the estimation of subjective probabilities from data. Past experimental data were first re-analysed based on the model. In Experiment 1, the superiority of the revised model was shown. However, when the relationship between antecedent and consequent was forced to deviate from the biconditional form, the model was not supported. In Experiment 2, it was shown that sufficient emphasis on probabilistic information can affect participants' performance. A detailed experimental method to sort participants by probabilistic strategies was introduced. Here, the model was supported by a subgroup of participants who used the probabilistic strategy. Finally, the results were discussed from the viewpoint of adaptive rationality.     

Strategy selection in question answering

There are multiple strategies for answering questions. For example, a statement is sometimes verified using a plausibility process and sometimes using a direct retrieval process. It is claimed that there is a distinct strategy selection phase and a framework is proposed to account for strategy selection. Six experiments support the assumptions of the proposed framework: The first three experiments show that strategy selection is under the strategic control of the subjects. These experiments also indicate what contextual variables affect this selection. Experiments 4 and 5 suggest that strategy selection also involves evaluating the question itself, while Experiment 6 suggests variables that influence the evaluation of the question. This model is shown to be consistent with processing strategies in domains other than question answering, viz., dual-task monitoring in divided attention situations.