Is effector visibility critical for performance asymmetries in the Simon task? Evidence from hand- and foot-press responses.

The Simon effect is a stimulus-response compatibility effect in which the spatial dimension of the stimulus is task-irrelevant. This effect is often larger in reaction time (RT) for the stimulus located on the dominant-hand side of participants, for most of which it is the right hand, due to dominant-hand keypress responses being faster than non-dominant-hand responses. Experiment 1 demonstrated that pedal-press responses with the left and right feet show a similar asymmetry, favoring the right response for right-footed persons. The asymmetric pattern for keypress responses was absent in results of Wallace (Journal of Experimental Psychology, 93, 163-168, 1972) when participants were not permitted to see the response keys or their hands placed on the keys at any time during the experiment, whereas we found the asymmetric pattern in a recent study when participants placed their hands on the keys prior to their being covered up. Experiments 2 and 3 showed that the Simon effect asymmetry for RT was evident even when participants were prevented from seeing the response device and their responding hands or feet. Although both hands and feet showed a Simon effect asymmetry in RT, consideration of incorrect responses suggested that whereas the asymmetry for hands is not due to a response bias, that for the feet may be due at least in part to such bias. Regardless, our results suggest that the Simon effect asymmetry is mainly an artifact of comparing conditions for which one response is made by the faster dominant right effector and the other with the slower non-dominant left effector.

Examining binding effects on task switch costs and response-repetition effects: Variations of the cue modality and stimulus modality in task switching.

Typically, response-repetition effects are obtained in task-switching experiments: In task repetitions, performance is enhanced when the response, too, repeats (response-repetition benefits), whereas in task switches, performance is impaired when the response repeats (response-repetition costs). A previous study introduced cue modality switches in a cued task-switching paradigm with visual stimuli and obtained enhanced response-repetition benefits when the cue modality repeated (Koch, Frings, & Schuch Psychological Research, 82, 570-579, 2018). In the present study, we aimed to replicate this finding with auditory stimuli (Exp. 1), and further examined whether response-repetition effects could be modulated by introducing stimulus modality switches (Exp. 2). We found clear evidence that the cue modality and stimulus modality affect task switch costs. The task switch costs were higher with a repeated cue modality or stimulus modality. However, cue modality switches or stimulus modality switches did not affect the response-repetition effects. We suggest that response-repetition effects are elicited by response-associated bindings, which are not necessarily affected by all episodic task features to the same extent. Our results are also in line with theoretical accounts that assume a hierarchical organization of task selection and response selection.

Response repetitions in auditory task switching: The influence of spatial response distance and of the response-stimulus interval.

In task switching studies, response repetition effects are typically obtained: When the task repeats, response repetitions are faster than response switches (response repetition benefit), but when the task switches, the opposite is found (response repetition cost). Previously, it was found that spatial response distance [RD] affected the response repetitions: separated response keys led to longer reaction times [RT] for response repetitions (in both task repetitions and task switches) than adjacent response keys. The goal of the present study was to replicate this RD effect in a modified setup with auditory stimuli (in Experiments 1 and 2). As we were interested in the temporal dynamics of the RD effect, we also introduced a block-wise manipulation of response-stimulus interval (RSI) in Experiment 2. RD modulated responding, replicating the results of a prior study that used visual stimuli, but only when the RSI was long. With short RSI, the RD effect was not obtained. At the same time, a long RSI led to more pronounced response repetition effects in the error rates. These results imply that response inhibition from the previous trial, which is assumed to contribute to the response repetition effect and to the modulation of responding by response distance, builds up over time.

The binding of an auditory target location to a judgement: A two-component switching approach.

In a two-component switching paradigm, in which participants switched between two auditory attention selection criteria (attention component: left vs. right ear) and two judgements (judgement component: number vs. letter judgement), we found high judgement switch costs in attention criterion repetitions, but low costs in attention criterion switches. This finding showed an interaction of components. Previous two-component switching studies observed differently emphasised interaction patterns. In the present study, we explored whether the strength of the interaction pattern reflects the strength of the binding of target location and judgement. Specifically, we investigated whether exogenous target location cueing led to weaker binding than endogenous cueing, and whether preparation for ear selection could influence the binding. Attention switches with auditory exogenous target location cues did not affect the component interaction pattern, whereas a prolonged preparation interval led to a more emphasised pattern. Binding between target location and judgement may therefore be rather automatic and may not necessarily require concurrent component processing. Sufficient time for target location switches with long preparation time may activate the previous trial's episode or facilitate switches of the subsequent judgement.

Auditory attention switching and judgment switching: Exploring multicomponent task representations.

An auditory attention-switching paradigm was combined with a judgment-switching paradigm to examine the interaction of a varying auditory attention component and a varying judgment component. Participants heard two dichotically presented stimuli-one spoken by a female speaker and one spoken by a male speaker. In each trial, the stimuli were a spoken letter and a spoken number. A visual explicit cue at the beginning of each trial indicated the auditory attention criterion (speaker sex/ear) to identify the target stimulus (Experiment 1) or the judgment that had to be executed (Experiment 2). Hence, the attentional selection criterion switched independently between speaker sexes (or between ears), while the judgment alternated between letter categorization and number categorization. The data indicate that auditory attention criterion and judgment were not processed independently, regardless of whether the attention criterion or the judgment was cued. The partial repetition benefits of the explicitly cued component suggested a hierarchical organization of the auditory attention component and the judgment component within the task set. We suggest that the hierarchy arises due to the explicit cuing of one component rather than due to a "natural" hierarchy of auditory attention component and judgment component.

Intentional preparation of auditory attention-switches: Explicit cueing and sequential switch-predictability.

In an auditory attention-switching paradigm, participants heard two simultaneously spoken number-words, each presented to one ear, and decided whether the target number was smaller or larger than 5 by pressing a left or right key. An instructional cue in each trial indicated which feature had to be used to identify the target number (e.g., female voice). Auditory attention-switch costs were found when this feature changed compared to when it repeated in two consecutive trials. Earlier studies employing this paradigm showed mixed results when they examined whether such cued auditory attention-switches can be prepared actively during the cue-stimulus interval. This study systematically assessed which preconditions are necessary for the advance preparation of auditory attention-switches. Three experiments were conducted that controlled for cue-repetition benefits, modality switches between cue and stimuli, as well as for predictability of the switch-sequence. Only in the third experiment, in which predictability for an attention-switch was maximal due to a pre-instructed switch-sequence and predictable stimulus onsets, active switch-specific preparation was found. These results suggest that the cognitive system can prepare auditory attention-switches, and this preparation seems to be triggered primarily by the memorised switching-sequence and valid expectations about the time of target onset.

Exploring handedness asymmetries in the Simon effect.

Spatially corresponding stimulus-response pairings usually produce shorter reaction times (RTs) than do non-corresponding pairings, even when the spatial dimension of the stimulus is irrelevant to the task. This "Simon effect" for visual stimuli and manual responses is often larger for the stimulus location on the side to which the person's dominant hand is operating. The present study aimed at replicating and examining the nature of this asymmetry. To determine whether the Simon effect asymmetry is a function of the hand distinction or of conceptual spatial codes, performance with left and right manual key-presses was compared to that with vocal responses "left" and "right." Whether the asymmetric Simon effect pattern is restricted to spatial stimuli was tested by comparing effects obtained with left and right located squares to those found with the centered words Left and Right. The asymmetry was only replicated for the spatial stimulus-manual response Simon task, for which a second experiment showed similar results when the hands and response box were not visible during task performance. The analysis revealed a general dominant-hand RT advantage that similarly adds to both corresponding and non-corresponding trials and is rather independent from the Simon effect. This advantage yields an apparent asymmetry when the data are analyzed as a function of correspondence for each stimulus location because the corresponding and non-corresponding RTs that are compared come from different hands.