On the limits of advance preparation for a task switch: do people prepare all the task some of the time or some of the task all the time?

This study investigated the nature of advance preparation for a task switch, testing 2 key assumptions of R. De Jong's (2000) failure-to-engage theory: (a) Task-switch preparation is all-or-none, and (b) preparation failures stem from nonutilization of available control capabilities. In 3 experiments, switch costs varied dramatically across individual stimulus-response (S-R) pairs of the tasks-virtually absent for 1 pair but large for others. These findings indicate that, across trials, task preparation was not all-or-none but, rather, consistently partial (full preparation for some S-R pairs but not others). In other words, people do not prepare all of the task some of the time, they prepare some of the task all of the time. Experiments 2 and 3 produced substantial switch costs even though time deadlines provided strong incentives for optimal advance preparation. Thus, there was no evidence that people have a latent capability to fully prepare for a task switch.     

Is the truth table task mistaken?

There is ample evidence that in classical truth table task experiments false antecedents are judged as “irrelevant”. Instead of interpreting this in support of a suppositional representation of conditionals, Schroyens (2010a Schroyens, W. 2010a. Mistaking the instance for the rule: A critical analysis of the truth-table evaluation paradigm. Quarterly Journal of Experimental Psychology, 63: 246–259. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar], 2010b Schroyens, W. 2010b. A meta-analytic review of thinking about what is true, possible, and irrelevant in reasoning from or reasoning about conditional propositions. European Journal of Cognitive Psychology, 22: 897–921. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) attributes it to the induction problem: the impossibility of establishing the truth of a universal claim on the basis of a single case. In the first experiment a truth table task with four options is administered and the correlation with intelligence is inspected. It is observed that “undetermined” is chosen in one third of the judgements and “irrelevant” in another third. A positive correlation is revealed between intelligence and the number of “irrelevant” and “undetermined” judgements. The data do not exclude that a part of the “irrelevant” judgements in classical truth table task experiments might be caused by the induction problem. In the second experiment participants are presented with a simplified four-option truth table task and asked for a justification of their judgements. These justifications show the induction problem is not the reason for choosing the “irrelevant” or “undetermined” option, which is supportive for a suppositional representation of conditionals.     

Rats’ acquisition of the ephemeral reward task

The ephemeral reward task provides a subject with a choice between two alternatives A and B. If it chooses alternative A, reinforcement follows and the trial is over. If it chooses alternative B, reinforcement follows but the subject can also respond to alternative A which is followed by a second reinforcement. Thus, it would be optimal to choose alternative B. Surprisingly, Salwiczek et al. (PLoS One 7:e49068, 2012. doi: 10.1371/journal.pone.00490682012) reported that adult fish (cleaner wrasse) mastered this task within 100 trials, whereas monkeys and apes had great difficulty with it. The authors attributed the species differences to ecological differences in the species foraging experiences. However, Pepperberg and Hartsfield (J Comp Psychol 128:298–306, 2014) found that parrots too learned this task easily. We have found that with a similar task pigeons are not able to learn to choose optimally within 400 trials (Zentall et al. in J Comp Psychol 130:138–144, 2016). In Experiment 1 of the present study, we found that rats did not learn to choose optimally in 840 trials; however, in Experiment 2 we added a prior commitment to the initial choice by increasing delay to reinforcement for the choice response from a single lever press to the first lever press after 20 s (FI20 s). In a comparable amount of training to Experiment 1, the rats learned to choose optimally. Although the use of a prior commitment increases the delay to reinforcement, it appears to reduce impulsive responding which in turn leads to optimal choice.     

Is the go/no-go lexical decision task preferable to the yes/no task with developing readers?

The lexical decision task is probably the most common laboratory visual word identification task together with the naming task. In the usual setup, participants need to press the “yes” button when the stimulus is a word and the “no” button when the stimulus is not a word. A number of studies have employed this task with developing readers; however, error rates and/or response times tend to be quite high. One way to make the task easier for young readers is by employing a go/no-go procedure: “If word, press ‘yes’; if not, refrain from responding.” Here we conducted a lexical decision experiment that systematically compared the yes/no and go/no-go variants of the lexical decision task with developing readers (second- and fourth-grade children). Results showed that (a) error rates for words and nonwords were much lower in the go/no-go task than in the yes/no task, (b) lexical decision times were substantially faster in the go/no-go task, and (c) there was less variability in the latency data of the go/no-go task for high-frequency words. Thus, the go/no-go lexical decision task is preferable to the “standard” yes/no task when conducting experiments with developing readers.     

Is the go/no-go lexical decision task an alternative to the yes/no lexical decision task?

In the go/no-go lexical decision task (LDT), participants are instructed to respond as quickly as they can when a word is presented and not to respond if a nonword is presented. By minimizing part of the response selection process in the experimental task, the impact of response decision time on the obtained lexical decision time is probably reduced relative to the standard yes/no LDT (Gordon, 1983). Experiments 1 and 2 show that the go/no-go LDT is sensitive to the effects of word frequency and associative priming--the magnitude of these effects is similar with the two tasks. More important, the go/no-go LDT has a number of advantages with respect to the "standard" yes/no LDT: It offers faster response times, more accurate responding, and fewer processing demands than does the yes/no task. Accordingly, the go/no-go task appears to be an excellent alternative to the standard yes/no task.     

The role of task rules and stimulus–response mappings in the task switching paradigm

Switch costs occur whenever participants are asked to switch between two or more task sets. In a typical task switching experiment, participants have to switch between two task sets composed of up to four different stimuli per task set. These 2 (task sets) x 4 (stimuli) contain only 8 different stimulus-response (S-R) mappings, and the question is why participants base their task performance on task sets instead of S-R mappings. The current experiments compared task performance based on task rules with performance based on single stimulus-response mappings. Participants were led to learn eight different S-R mappings with or without fore-knowledge about two underlying task sets. Without task set information no difference between shifts and repetitions occurred, whereas introducing task sets at the beginning led to significant switch costs. Most importantly, introducing task sets in the middle of the experiment also resulted in significant switch costs. Furthermore, introducing task rules at the beginning of the experiment lead to slower RTs when simple stimuli (Experiment 1) had to be processed. This detrimental effect disappeared with more complex stimuli (Experiment 2). Results will be discussed with respect to cognitive control.     

When the voluntary mind meets the irresistible event: Stimulus–response correspondence effects on task selection during voluntary task switching

In the present study, we investigated how task selection is biased by inherent stimulus characteristics in the voluntary task-switching paradigm. We used digits as the task stimuli, since they may automatically induce spatially horizontal representations of numbers. Specifically, we examined whether an irrelevant spatial representation of a number coincides with its associated response codes and whether such a stimulus–response (S–R) correspondence effect biases task selection for a digit. Participants were randomly assigned to one of two different action code layout conditions: Two numerical tasks were arranged as inner/outer in the horizontal layout condition or as upper/down in the vertical layout condition. Participants in the horizontal layout condition were more likely to choose a task when the task’s action code and the digit’s spatial representation corresponded, as compared with when they did not. On the other hand, no selection bias was observed in the vertical layout condition, since there was no overlapping spatial representation between the stimulus and response. The present study extends previous findings by considering the influence of the stimulus-driven effect on task selection with regard to the S–R correspondence effect.     

Prioritizing—The task strategy of the powerful?

Previous research has shown that power increases focus on the main goal when distractor information is present. As a result, high-power people have been described as goal-focused. In real life, one typically wants to pursue multiple goals at the same time. There is a lack of research on how power affects how people deal with situations in which multiple important goals are present. To address this question, 158 participants were primed with high or low power or assigned to a control condition, and were asked to perform a dual-goal task with three difficulty levels. We hypothesized and found that high-power primed people prioritize when confronted with a multiple-goal situation. More specifically, when task demands were relatively low, power had no effect; participants generally pursued multiple goals in parallel. However, when task demands were high, the participants in the high-power condition focused on a single goal whereas participants in the low-power condition continued using a dual-task strategy. This study extends existing power theories and research in the domain of goal pursuit.     

Signal detection models for the same–different task

Signal detection models for the same–different task are presented. In contrast to the standard approach that only considers the proportion correct, the models apply to the full four by two same–different table. The approach allows one to consider models that recognize bias and other effects. Two basic signal detection models, associated with different decision rules, are presented. A version of the covert decisions rule is introduced that directly allows for same–different bias, in contrast to earlier versions. It is shown how to fit the models with standard software for nonlinear mixed models. The models are applied to data from a recent same–different study.     

Measuring “intuition” in the SRT generation task

We address some concerns related to the use of post-trial attribution judgments, originally developed for artificial grammar learning (AGL), during the version of the serial reaction time (SRT) task used by Fu, Dienes, and Fu (2010). In particular, intuition attributions, which are central to Fu et al.’s arguments, seem problematic: This attribution is likely to be made when stimuli contain several competing sources of information to which subjective feelings could be attributed. The interpretation of intuition attributions in Fu et al.’s SRT generation task is problematic because the procedure involved a 2-element sequence where items varied only in position. In our view, responses categorised as intuitions might have been a variety of guess response where neither judgement knowledge nor structural knowledge were conscious. The results would then be compatible with previous findings showing that people can control the use of unconscious structural knowledge even when judgement knowledge is unconscious.     

Cue–task associations in task switching

Cognitive flexibility can be studied using the task-switching paradigm. This paradigm requires subjects to adapt behaviour to changing contexts as indicated by a cue. In our study, we addressed the question of how cue-based implementation of mental “task sets” occurs. We assumed that cues build up associations to the tasks that they indicate. These associations lead to retrieval of the associated task set once the cue shows up again. In three experiments, we tested this assumption using a negative transfer paradigm. First participants were exposed to one cue–task mapping. After a training phase, the cue–task mapping changed in either of two ways. Whereas one group of participants got new cues, the other experienced a reversal of the learnt cue–task mapping. Our results show that participants build up cue–task associations and that these formerly learnt associations can hamper the implementation of new cue–task mappings (particular with mapping reversal). Prolonged preparation time decreased the cost of changing the cue–task mapping but did not change the overall pattern of results.     

Implicit task sets in task switching?

In 2 experiments, the authors compare stimulus-based versus task-rule-based task performance. Participants practiced 8 stimulus-response mappings either with or without knowledge about 2 underlying task sets. After practice, 2 transfer blocks with 8 new stimuli were presented. Results show that rule knowledge leads to significant switch and transfer costs, whereas without rule knowledge neither switch nor transfer costs occur. However, significant Task Type x Response Type interactions occurred in both conditions. In a second experiment including only the no rule condition, half of the stimulus-response mappings in the transfer blocks were incongruent to the underlying task rule. Slower response times for these incongruent stimuli as compared with congruent stimuli and the absence of switch costs suggest that participants acquired (presumably implicit) knowledge about 4 different stimulus-response categories.     

“Smart inhibition”: electrophysiological evidence for the suppression of conflict-generating task rules during task switching

A major challenge for task switching is maintaining a balance between high task readiness and effectively ignoring irrelevant task rules. This calls for finely tuned inhibition that targets only the source of interference without adversely influencing other task-related representations. The authors show that irrelevant task rules generating response conflict are inhibited, causing their inefficient execution on the next trial (indicating the presence of competitor rule suppression[CRS];Meiran, Hsieh, & Dimov, Journal of Experimental Psychology: Learning, Memory and Cognition, 36, 992–1002, 2010). To determine whether CRS influences task rules, rather than target stimuli or responses, the authors focused on the processing of the task cue before the target stimulus was presented and before the response could be chosen. As was predicted, CRS was found in the event-related potentials in two time windows during task cue processing. It was also found in three time windows after target presentation. Source localization analyses suggest the involvement of the right dorsal prefrontal cortex in all five time windows.     

An examination of the continuous distractor task and the “long-term recency effect”

The continuous distractor task has yielded a so-called "long-term recency effect" that appears to call into question the dual-storage explanation of serial position effects in free recall. In this study, we show that the "long-term recency effect" is really a short-term storage effect, resulting from adaptation to the repeated presentation of a particular type of distractor throughout the list. This adaptation, a time-sharing process, permits short-term storage to carry out its normal functions. Experiment 1 shows that an appropriate postlist distractor task does in fact eliminate the "long-term recency effect." This finding supports the assertion that the effect is a product of short-term storage. Experiment 2 demonstrates the benefits and costs of the time-sharing process, relative to standard free recall, for both long-term and short-term storage. The findings support the time-sharing hypothesis. Experiment 3 replicates Experiment 2, with a change in procedure that rules out output interference as a mechanism responsible for the results of Experiment 2. Data are also presented on the development of the adaptation over trials. It is concluded that the adaptation and time-sharing processes need to be included in the dual-storage model of short-term storage.     

Inducing an availability heuristic on the Wason selection task overrides the matching bias

A long history of examining reasoning using the Wason selection task has revealed that many respondents are biased towards choices that match the items expressed in the rule. One reason for this particular heuristic may be that no better information is immediately available, and thus matching items win over the competing choice simply via recognition. In two experiments, we sought to examine whether a stronger memory trace could override the matching bias. We created rules from common, easily recognisable nursery rhymes and varied the degree to which the presented rules matched the commonly known rhymes. The components of the remembered rhyme had a strong influence on the participants’ selections, suggesting that a strong memory trace can override the usual matching bias. We provide an interpretation of these results in light of answer fluency, mental models, and probabilistic estimates.     

Repetition priming in task switching: Do the benefits dissipate?

In task-switching research, one process that has been implicated as a possible source of switch cost is repetition priming. In four experiments, an examination was made of the claim that repetition priming dissipates over the interval between trials and thereby causes switch cost to decrease with increases in the response-cue interval (RCI). In Experiments 1 and 2, RCI was manipulated within participants, producing the standard RCI effect on switch cost. In Experiments3 and 4, RCI was manipulated between participants and had no effect on switch cost. The role of experimental design and the mixed pattern of effects on switch and repeat trials in Experiments1 and 2 suggest that a passive architectural process such as priming dissipation is not responsible for the RCI effect on switch cost. Repetition priming may still be responsible for some or all of switch cost, but it appears to be more stable over time than was previously thought.     

Does sunshine prime loyal? Affective priming in the naming task

Recent work has found an affective priming effect using the naming task: In pronouncing target words, pronunciation latencies were consistently shorter when the target (e.g., loyal) was preceded by an evaluatively congruent (e.g., sunshine) rather than incongruent prime word (e.g, rain). Using the naming task, no affective priming was found in the present studies irrespective of prime-set size and target-set size (Experiment 1), irrespective of stimulus-onset asynchrony (Experiment 2), and even when a nearly exact replication of previous work that demonstrated the effect was conducted (Experiment 3). Finally, bilingual German/English speakers exhibited strong associative priming, but no affective priming, in both the English as well as the German language (Experiment 4). The results show that priming for evaluatively related words is not a general finding.     

Transposed-letter priming effect in Hebrew in the same–different task

We investigated the interaction between morphological structure and transposed-letter priming using the same–different task with Hebrew, a Semitic language in which morphology has been shown to play a key role in visual word recognition. In contrast to the results observed with lexical decision (e.g., Velan & Frost, 2009, 2011), a transposed-letter priming effect was observed irrespective of the morphological structure of the words. We take these results to suggest that morphological decomposition occurs only in the service of lexical access. We discuss further a unique feature of written Arabic, another Semitic language, to explain the apparent conflict between our findings and those reported by Perea, Abu Mallouh, García-Orza, and Carreiras (2010).     

Understanding “because”: How important is the task?

The causal connective because requires the order of clauses within a sentence to violate the order of events in the real world; i.e., effect because cause is correct. Children's (4, 6, and 8 years of age) ability to comprehend because was explored in a series of four studies. The first, a replication with variations of existing studies, assessed children's ability to judge as anomalous sentences in which the order of clauses is reversed. Comprehension of impersonal sentences is better than of sentences derived from narratives of their own experiences, although children do poorly at this task until age 8. However, results of study 2 suggest that children's poor understanding of task requirements is partly responsible, since increased task instructions and modeling led to significant improvement in the ability of preschoolers to judge sentences as anomalous. In the third study, children named the cause event after being told a causal sequence (involving either psychological or physical causality) of the form: Event A, Event C (effect) because Event B (cause), Event D. Comprehension of physical causality sequences is superior, but again, only 8-year-olds showed good performance. In Study 4, children were asked to find the cause event in four-clause sequences of the same form as in Study 3, but memory props were added in the form of pictures of events A, B, and D. Near perfect performance was shown by all children. Overall, comprehension studies of because are judged to be rife with methodological problems, and memory demands are seen to be particularly important.The authors wish to thank Lynn Anne Pye for her contributions to Study 4, which formed part of her undergraduate honors degree research, as well as F. Michael Rabinowitz for his comments and statistical aid. This research was supported by NSERC grant A7911 to the senior author.