Introducing a control condition in the classic oddball paradigm: Oddballs are overestimated in duration not only because of their oddness.

Three experiments assessed whether participants perceive infrequent stimuli (oddballs) to last longer than frequent ones (standards). The classical oddball paradigm was modified so that participants judged the duration of a target stimulus which could either be a standard or an oddball. The target was always the fifth stimulus in the stream and all stimuli were presented at predefined spatial positions. These modifications enabled a direct comparison of duration judgments for oddballs and standards. In Experiments 1 and 2 not only the duration of oddballs but also the duration of standards was overestimated by virtually the same amount. In other words, the overestimation of oddballs was not due to their oddness but reflected a different temporal dilation such as the negative time-order error. In Experiment 3, all stimuli were presented at the same spatial position. Again, both oddballs and standards were overestimated, however, oddballs more so. The present results highlight the importance of comparing the judged duration of oddballs and standards when evaluating the size of the genuine oddball effect. Furthermore, the findings suggest that the occurrence of temporal oddball effects can depend on spatial features of stimulus presentation.

The influence of dichotical fusion on the redundant signals effect, localization performance, and the mismatch negativity.

In two experiments, each including a simple reaction time (RT) task, a localization task, and a passive oddball paradigm, the physical similarity between two dichotically presented auditory stimuli was manipulated. In both experiments, a redundant signals effect (RSE), high localization performance, and a reliable mismatch negativity (MMN) was observed for largely differing stimuli, suggesting that these are coded separately in auditory memory. In contrast, no RSE and a localization rate close to chance level (experiment 1) or at chance (experiment 2) were observed for stimuli differing to a lesser degree. Crucially, for such stimuli a small (experiment 1) or no (experiment 2) MMN were observed. These MMN results indicate that such stimuli tend to fuse into a single percept and that this fusion occurs rather early within information processing.

Electrophysiological evidence for response priming and conflict regulation in the auditory Simon task.

The Simon effect refers to the finding that responses are faster when the task-irrelevant stimulus and response location correspond than when they do not. The present study examined the role of location-based response priming and its regulation by an ancillary monitoring mechanism (AMM) for the auditory Simon effect, manipulating response modality and analyzing event-related brain potentials (ERPs). An auditory Simon effect was obtained for responses with hand, foot, and eyes. Lateralized ERPs revealed a mix of location-based attentional and motor-related activations early on during information processing. The Simon effect in reaction time (RT) was absent or largely reduced when a non-corresponding rather than a corresponding trial preceded, indicating control over location-based response priming. Importantly, RT modulations as a function of the correspondence sequence were mirrored in the amplitude of a negative difference wave (N2c), in accord with the view that response priming is under control of an AMM. In conclusion, both behavioral and electrophysiological measures revealed effect patterns that are consistent with an information-processing model that assumes asynchronous transmission from two separate processing routes to the motor system and top-down control by an AMM over task-irrelevant response priming.