Denise Nadine Stephan

Central Cross-Talk in Task Switching: Evidence From Manipulating Input―Output Modality Compatibility

Two experiments examined the role of compatibility of input and output (I-O) modality mappings in task switching. We define I-O modality compatibility in terms of similarity of stimulus modality and modality of response-related sensory consequences. Experiment 1 included switching between 2 compatible tasks (auditory-vocal vs. visual-manual) and between 2 incompatible tasks (auditory-manual vs. visual-vocal). The resulting switch costs were smaller in compatible tasks compared to incompatible tasks. Experiment 2 manipulated the response-stimulus interval (RSI) to examine the time course of the compatibility effect. The effect on switch costs was confirmed with short RSI, but the effect was diminished with long RSI. Together, the data suggest that task sets are modality specific. Reduced switch costs in compatible tasks may be due to special linkages between input and output modalities, whereas incompatible tasks increase cross-talk, presumably due to dissipating interference of correct and incorrect response modalities.

The role of input–output modality compatibility in task switching

Input–output (I–O) modality compatibility refers to the similarity of stimulus modality and modality of response-related sensory consequences. A previous study found higher switch costs in task switching in I–O modality incompatible tasks (auditory-manual and visual-vocal) than in I–O modality compatible tasks (auditory-vocal and visual-manual). However, these tasks had spatially compatible S–R mappings, which implied dimensional overlap (DO). DO may have led to automatic activation of the corresponding compatible responses in the incorrect response modality, thus increasing interference effects. The present study was aimed to examine the influence of DO on I–O modality compatibility effects. In two experiments, we found that I–O modality compatibility affects task switching even in tasks without DO, which even tended to result in further increased modality influences. This finding suggests that I–O modality mappings affect response selection by affecting between-task cross-talk not on the level of specific response codes but on the level of modality-specific processing pathways.

Task Switching, Modality Compatibility, and the Supra-Modal Function of Eye Movements

Previous research suggested that specific pairings of stimulus and response modalities (visual-manual and auditory-vocal tasks) lead to better dual-task performance than other pairings (visual-vocal and auditory-manual tasks). In the present task-switching study, we further examined this modality compatibility effect and investigated the role of response modality by additionally studying oculomotor responses as an alternative to manual responses. Interestingly, the switch cost pattern revealed a much stronger modality compatibility effect for groups in which vocal and manual responses were combined as compared to a group involving vocal and oculomotor responses, where the modality compatibility effect was largely abolished. We suggest that in the vocal-manual response groups the modality compatibility effect is based on cross-talk of central processing codes due to preferred stimulus-response modality processing pathways, whereas the oculomotor response modality may be shielded against cross-talk due to the supra-modal functional importance of visual orientation.

Shifts in target modality cause attentional reset: Evidence from sequential modulation of crossmodal congruency effects

Reduced congruency effects after a preceding incongruent trial suggest a conflict-monitoring process, which reactively triggers the recruitment of attentional control in subsequent trials. In the present study, we assessed this sequential modulation of crossmodal congruency effects separately in two different tasks. Participants performed a location judgment task and a numerical judgment task in a block-wise fashion in a modality-switching paradigm. Stimuli were presented simultaneously in two modalities and were either congruent or incongruent (e.g., left visual object, right sound) with each other. The target modality was indicated by a cue, so that the target modalities either repeated or switched in successive trials. For both tasks, the results indicated reduced congruency effects after an incongruent trial only for modality repetitions, but not for switches. This finding suggests that modality switches induce a shift in episodic context, which in turn leads to an attentional reset. This reset eliminates the sequential modulation of congruency effects.

Emerging features of modality mappings in task switching: modality compatibility requires variability at the level of both stimulus and response modality

The term modality compatibility refers to the similarity between the stimulus modality and the modality of response-related sensory consequences. Previous research showed evidence for modality compatibility benefits in task switching, when participants switch either between two modality compatible tasks (auditory-vocal and visual-manual) or between two modality incompatible tasks (auditory-manual and visual-vocal). However, it remained unclear whether there is also a modality compatibility benefit when participants switch between a modality compatible and an incompatible task. To this end, in Experiment 1, we kept the same design as in earlier studies, so participants had to switch either between modality compatible or modality incompatible spatial discrimination tasks, but in Experiment 2A, participants switched at the response level (manual/vocal) while we kept the stimulus modality constant across tasks, and in Experiment 2B, they switched at the stimulus level (visual/auditory) while we kept the response modality constant across tasks. We found increased switch costs in modality incompatible tasks in Experiment 1, but no such a difference between modality compatible and incompatible tasks in Experiment 2A and 2B, supporting the idea that modality incompatible tasks increase crosstalk, due to the response-based priming of the competing task, but this crosstalk is reduced if the competing task involves either the same stimulus modality or the same response modality. We conclude that a significant impact of modality compatibility in task switching requires variability at the level of both stimulus and response modality.

The other modality: Auditory stimuli in language switching

Language switching studies typically implement visual stimuli and visual language cues to trigger a concept and a language response, respectively. In the present study we set out to generalise this to another stimulus modality by investigating language switching with auditory stimuli next to visual stimuli. The results showed that switch costs can be obtained with both auditory and visual stimuli. Yet, switch costs were relatively larger with visual stimuli than with auditory stimuli. Both methodological and theoretical implications of these findings are discussed.

The interplay of crossmodal attentional preparation and modality compatibility in cued task switching

Two experiments examined the influence of preparation on modality compatibility effects in task switching. The term modality compatibility refers to the similarity between the stimulus modality and the modality of response-related sensory consequences. Previous research showed evidence for modality compatibility benefits in task switching when participants switched either between two modality compatible tasks (auditory-vocal and visual-manual) or between two modality incompatible tasks (auditory-manual and visual-vocal). In this study, we investigated the influence of active preparation on modality compatibility effects in task switching. To this end, in Experiment 1, we introduced unimodal modality cues, whereas in Experiment 2, bimodal abstract cues were used. In both experiments, the cue-stimulus interval (CSI) was manipulated while holding the response-stimulus interval (RSI) constant. In both experiments, we found not only decreased switch costs with long CSI but also the elimination of the residual switch costs. More importantly, this preparation effect did not modulate the modality compatibility effect in task switching. To account for this data pattern, we assume that cue-based preparation of switches by modality mappings was highly effective and produced no residual reaction time (RT) costs with long CSI.

Modality-specific preparatory influences on the flexibility of cognitive control in task switching

ABSTRACT In the current study, we addressed modality-specificity of the flexibility of cognitive control. We compared performance in single-task and mixed-tasks blocks between blocked auditory and visual stimuli assessing alternation costs (single vs. mixed). Mixed blocks comprised task switches only. The tasks consisted of numerical parity, magnitude, and distance judgments about numbers between one and nine without five. A cue indicated the relevant task. The cue–stimulus interval was varied (short vs. long interval) to examine preparation effects. The results indicated higher response times (RTs) and error rates (ERs) in mixed- vs. single-tasks blocks. The alternation costs in ERs were larger for auditory compared to visual stimulus presentation. Moreover, the reduction of RT alternation costs based on increased preparation time was more pronounced for the auditory modality compared to the visual modality. These results suggest a modality-specific influence on processes involved in maintaining and updating task sets in working memory.

Modality compatibility biases voluntary choice of response modality in task switching

The term modality compatibility refers to the similarity between stimulus modality and the modality of response-related sensory consequences (e.g., vocal responses produce auditory effects). The previous results showed smaller task-switching costs when participants switched between modality compatible tasks (auditory–vocal and visual–manual) compared to switching between modality incompatible tasks (auditory–manual and visual–vocal). In the present study using a voluntary task-switching paradigm (VTS), participants chose the response modality (vocal or manual) to indicate the location of either a visual or an auditory stimulus. We examined whether free task choices were biased by modality compatibility, so that modality compatible tasks are preferred in VTS. The choice probability analysis indicated that participants tended to choose the response modality that is compatible to the stimulus modality. However, participants did not show a preference to repeat a stimulus–response (S–R) modality mapping, but to switch between modality compatibility (i.e., from S–R modality compatible mapping to S–R modality incompatible mapping and vice versa). More interestingly, even though participants freely chose the response modality, modality compatibility still influenced task-switching costs, showing larger costs with modality incompatible mappings. The finding that modality compatibility influenced choice behaviour suggests components of both top–down control and bottom–up effects of selecting a response modality for different stimulus modalities.

Influences of Postural Control on Cognitive Control in Task Switching

The aim of the current study was to investigate the effects of postural control demands on cognitive control processes in concurrent auditory-manual task switching. To this end, two experiments were conducted using an auditory cued task-switching paradigm with different postural control demands (sitting vs. standing). This design allowed us to explore the effect of postural control on switch costs, mixing costs, and the between-task congruency effect. In addition, we varied the cue-based task preparation in Experiment 1 to examine whether preparation processes are independent of additional postural control demands or if the motor control processes required by the postural control demands interfere with task-specific cognitive preparation processes. The results show that we replicated the standard effects in task switching, such as switch costs, mixing costs, and congruency effects in both experiments as well as a preparation-based reduction of these costs in Experiment 1. Importantly, we demonstrated a selective effect of postural control demands in task switching in terms of an increased congruency effect when standing as compared to sitting. This finding suggests that particularly in situations that require keeping two tasks active in parallel, the postural control demands have an influence on the degree to which cognitive control enforces a more serial (shielded) mode or a somewhat less selective attention mode that allows for more parallel processing of concurrently held active task rules.