Electrophysiological correlates of crossmodal visual distractor congruency effects: Evidence for response conflict

To investigate the basis of crossmodal visual distractor congruency effects, we recorded event-related brain potentials (ERP) while participants performed a tactile location-discrimination task. Participants made speeded tactile location-discrimination responses to tactile targets presented to the index fingers or thumbs while ignoring simultaneously presented task-irrelevant visual distractor stimuli at either the same (congruent) or a different (incongruent) location. Behavioural results were in line with previous studies, showing slowed response times and increased error rates on incongruent compared with congruent visual distractor trials. To clarify the effect of visual distractors on tactile processing, concurrently recorded ERPs were analyzed for poststimulus, preresponse, and postresponse modulations. An enhanced negativity was found in the time range of the N2 component on incongruent compared with congruent visual distractor trials prior to correct responses. In addition, postresponse ERPs showed the presence of error-related negativity components on incorrect-response trials and enhanced negativity for congruent-incorrect compared with incongruent-incorrect trials. This pattern of ERP results has previously been related to response conflict (Yeung, Botvinick, & Cohen, 2004). Importantly, no modulation of early somatosensory ERPs was present prior to the N2 time range, which may have suggested the contribution of other perceptual or postperceptual processes to crossmodal congruency effects. Taken together, our results suggest that crossmodal visual distractor effects are largely due to response conflict.     

Attentional cueing by cross-modal congruency produces both facilitation and inhibition on short-term visual recognition

The attentional modulation of performance in a memory task, comparable to the one obtained in a perceptual task, is at the focus of contemporary research. We hypothesized that a biphasic effect (namely, facilitation followed by inhibition) can be obtained in visual working memory when attention is cued towards one item of the memorandum and participants must recognize a delayed probe as being identical to any item of the memorandum. In every trial, a delayed spiky/curvy probe appeared centrally, to be matched with the same-category shape maintained in visual working memory which could be either physically identical (positive trials) or only categorically similar (negative trials). To orient the participant's attention towards a selected portion of a two-item memorandum, a (tzk/wow) sound was played simultaneously with two lateral visual shapes (one spiky and one curved). Our results indicate that an exogenous attentional shift during perception of the memorandum, induced by a congruent audio–visual pairing, first facilitates and then inhibits the recognition of a cued item (but not of a non-cued item) stored in visual working memory. A coherent pattern of individual differences emerged, indicating that the amount of early facilitation in congruent-sound trials was negatively correlated with recognition sensitivity in no-sound trials (suggesting that the inverse effectiveness rule may also apply to memory) and positively correlated with later inhibition, as well as with the self-reported susceptibility to memory failures.     

Instruction-based task-rule congruency effects

In the present study, we investigated the functional characteristics of task sets that were never applied before and were formed only on the basis of instructions. We tested if such task sets could elicit a task-rule congruency effect, which implies the automatic activation of responses in the context of another task. To this end, a novel procedure was developed that revealed instruction-based task-rule congruency effects in 2 experiments. Although the effect seems quite general (Experiment 1), it still necessitates the formation of a task set, as it cannot be induced by the mere maintenance of instructions in declarative working memory (Experiment 2). We conclude that a task set representing only key features of an upcoming task can be formed on the basis of instructions alone to such a degree that it can automatically trigger a response tendency in another task. Implications of our results for the impact of instructions on performance in general and for the occurrence of task-rule congruency effects in particular are discussed. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Modeling spatial effects in visual-tactile saccadic reaction time

Saccadic reaction time (SRT) to visual targets tends to be shorter when nonvisual stimuli are presented in close temporal or spatial proximity, even when subjects are instructed to ignore the accessory input. Here, we investigate visual-tactile interaction effects on SRT under varying spatial configurations. SRT to bimodal stimuli was reduced by up to 30 msec, in comparison with responses to unimodal visual targets. In contrast to previous findings, the amount of multisensory facilitation did not decrease with increases in the physical distance between the target and the nontarget but depended on (1) whether the target and the nontarget were presented in the same hemifield (ipsilateral) or in different hemifields (contralateral), (2) the eccentricity of the stimuli, and (3) the frequency of the vibrotactile nontarget. The time-window-of-integration (TWIN) model for SRT (Colonius & Diederich, 2004) is shown to yield an explicit characterization of the observed multisensory spatial interaction effects through the removal of the peripheral-processing effects of stimulus location and tactile frequency.     

Spatial selection via feature-driven inhibition of distractor locations

The allocation of spatial attention was measured with detection probes at different locations. Response times were faster for probes at the location of the target digit, which subjects reported, than at the locations of distractor digits, which they ignored. Probes at blank locations between stimuli produced fast responses, indicating that selection was accomplished by inhibiting distractor locations but not other areas. Unlike earlier studies using location cuing with simpler stimuli, these experiments showed no attentional differences across horizontal or vertical midlines. Attention varied little with distance from the target, although blank locations far from the target were somewhat less attended than were those near the target, and attention was only slightly affected by expectations for stimulus location. This task demonstrates a form of feature-driven spatial attention, in which locations with objects lacking target features are inhibited.     

Gender congruency effects in picture naming

The analysis of speech error corpora in various gender-marked languages has shown that noun substitutions tend to preserve grammatical gender. This result has been taken as an indication that grammatical gender could play a constraining role during the process of lexical selection. To gain insights on the status of grammatical gender in the speech production system, we discuss this hypothesis and we report three picture naming experiments. We attempted to observe gender-marked context effects in the course of error-free speech production. Participants named pictures shortly after processing a prime that was or was not gender marked and that was or was not congruent with the name of the picture. A clear congruency effect was observed, involving both facilitation in the gender congruent conditions and inhibition in gender incongruent conditions. Different interpretations of this effect and of previously reported gender context effects are discussed in the context of current models of speech production.     

Simon congruency effects based on stimulus and response numerosity

Three choice reaction time experiments documented a Simon-type congruence effect involving the numbers of stimuli and responses. In Experiment 1 the stimulus consisted of one or two high- or low-pitch tones, and participants were required to respond with one or two taps of a response key depending on stimulus pitch. Responses were faster when the number of tones matched the required number of response taps than when these numbers mismatched. Experiment 2 showed that a weaker version of this effect can also be obtained using visual stimuli, and Experiment 3 showed that the analogous effect can even be obtained, albeit very weakly, with bimodal stimuli. There was also evidence that the number of stimuli affected the rate of emitting the two-tap response. These results indicate that stimulus numerosity is processed automatically to the level at which it can affect the selection and possibly the execution of a varying number of responses.     

Simon congruency effects based on stimulus and response numerosity

Three choice reaction time experiments documented a Simon-type congruence effect involving the numbers of stimuli and responses. In Experiment 1 the stimulus consisted of one or two high- or low-pitch tones, and participants were required to respond with one or two taps of a response key depending on stimulus pitch. Responses were faster when the number of tones matched the required number of response taps than when these numbers mismatched. Experiment 2 showed that a weaker version of this effect can also be obtained using visual stimuli, and Experiment 3 showed that the analogous effect can even be obtained, albeit very weakly, with bimodal stimuli. There was also evidence that the number of stimuli affected the rate of emitting the two-tap response. These results indicate that stimulus numerosity is processed automatically to the level at which it can affect the selection and possibly the execution of a varying number of responses.     

Orientation congruency effects on the identification of disoriented shapes

Effects of orientation on identification can be attenuated when other patterns at the same (or a similar) orientation are identified in close temporal contiguity. In Experiments 1 and 2, letters were presented simultaneously in brief masked displays. Identification accuracy was much higher when the letters had consistent orientations than when the letters had different orientations within a display. In Experiment 3, two letters were presented sequentially. Identification accuracy was higher with congruent than with incongruent orientations. The results are unexpected if one assumes that the patterns themselves are rotated until upright prior to their identification, unless pattern rotation processes can be primed, and that priming requires orientation congruence between the priming and primed stimulus. The results are expected if the orientation of a frame of reference can be adjusted to the orientation of the patterns during the identification process.     

Working memory and target-related distractor effects on visual search

We examined two forms of top-down effects on visual selection: (1) information held in working memory (WM) and (2) the semantic relations between targets and distractors. We found that items held in WM affected search for a different target. This WM-based interference effect generalized across different exemplars, even though participants could remember the specific exemplar on the trial. This argues against a memory top-up account of performance. In addition, there was interference from distractors that were not held in WM but were semantically related to the target. The effects of WM capture and the effects of capture by a distractor related to the target combined additively. The data suggest that task-irrelevant information in WM and task-relevant templates for targets compete separately for selection. The implications for understanding top-down processes in search are discussed.     

Asymmetric cross-modal effects in time perception

It is common to judge the duration of an audiovisual event, and yet it remains controversial how the judgment of duration is affected by signals from other modalities. We used an oddball paradigm to examine the effect of sound on the judgment of visual duration and that of a visual object on the judgment of an auditory duration. In a series of standards and oddballs, the participants compared the duration of the oddballs to that of the standards. Results showed asymmetric cross-modal effects, supporting the auditory dominance hypothesis: a sound extends the perceived visual duration, whereas a visual object has no effect on perceived auditory duration. The possible mechanisms (pacemaker or mode switch) proposed in the Scalar Expectancy Theory [Gibbon, J., Church, R. M., & Meck, W. H. (1984). Scalar timing in memory. In J. Gibbon & L. Allan (Eds.), Annals of the New York Academy of Sciences: Vol. 423. Timing and time perception (pp. 52–77). New York: New York Academy of Sciences] were examined using different standard durations. We conclude that sound increases the perceived visual duration by accelerating the pulse rate in the visual pacemaker.     

Effector system-specific sequential modulations of congruency effects

Congruency effects in conflict tasks are reliably reduced after experiencing conflict, that is, following incongruent trials. Such sequential modulations (sometimes referred to as the Gratton effect) indicate the operation of conflict adaptation mechanisms. The influential conflict monitoring hypothesis suggested that after conflict the processing of relevant stimulus dimensions is increased. Alternatively, it was suggested that the influence of automatic response activation is suppressed following conflict. In two experiments, participants worked on the same cognitive task (Experiment 1: Eriksen flanker; Experiment 2: Simon) with the same kind of stimulation. A cue indicated whether they should respond with the hands or the feet. When the effector system repeated from the previous trial, a sequential modulation was reliably observed. When the effector system switched, however, the sequential modulation collapsed. These results are taken to argue for the suppression of effector system-specific response activations as a consequence of experiencing conflict. Alternative interpretations in terms of task-set and/or context switches are discussed.     

Sequential congruency effects in implicit sequence learning

We deal with situations incongruent with our automatic response tendencies much better right after having done so on a previous trial than after having reacted to a congruent trial. The nature of the mechanisms responsible for these sequential congruency effects is currently a hot topic of debate. According to the conflict monitoring model these effects depend on the adjustment of control triggered by the detection of conflict on the preceding situation. We tested whether these conflict monitoring processes can operate implicitly in an implicit learning procedure, modulating the expression of knowledge of which participants are not aware. We reanalyze recently published data, and present an experiment with a probabilistic sequence learning procedure, both showing consistent effects of implicit sequence learning. Despite being implicit, the expression of learning was reduced or completely eliminated right after trials incongruent with the learned sequence, thus showing that sequential congruency effects can be obtained even when the source of congruency itself remains implicit.     

Orientation congruency effects in visual search.

Subjects searched for the letter E in a background of Ls and Fs in displays that had 1, 2, 4, 8, or 12 letters. The letters could be shown at one of six orientations (upright or rotated clockwise in 60 degrees increments). The displays were either congruent for orientation (all letters had the same orientation) or incongruent (letters in haphazard orientations except for the target on E-present trials). Search time increased linearly with the number of letters in the display, and more so for E-absent trials than for E-present trials. Letter orientation, in general, increased search time and produced an M-shaped function. Furthermore, orientation effects were attenuated in congruent displays relative to those produced by incongruent displays. The results demonstrated systematic orientation effects on the time to search for a simple pattern embedded in simple backgrounds, and provided converging evidence for the orientation-congruency effect found by Jolicoeur (1990b, Journal of Experimental Psychology: Human Perception and Performance, 16, 351-364).     

Item-specific congruency effects in nonverbal auditory Stroop

In the current study, participants judged as 'low' or 'high' either the location or the frequency of a single tone presented in one of two locations at one of two frequencies. The classification associated with the irrelevant feature could be either congruent or incongruent with the required response. The results of Experiment 1 revealed that responses were made more slowly on incongruent than on congruent trials, regardless of whether participants judged sounds according to their location or their pitch. In Experiment 2, we manipulated the probability that the classification associated with the irrelevant acoustic feature was consistent with the classification associated with the task-relevant dimension. In this experiment responses were made more quickly on congruent trials when the response associated with the irrelevant feature was likely to be consistent with the required response, and on incongruent trials when the response associated with the irrelevant feature was likely to be inconsistent with the required response.     

Visual and tactile cross-modal mere exposure effects

The affective system enables people to perceive and judge the emotional content of stimuli from various sensory modalities. Cross-modal interactions in affective processes, however, are less well understood. Using novel three-dimensional objects, we investigated cross-modal mere exposure effects between vision and touch. Previewing objects increased the preference judged by hand, while pre-touching did not modulate the preference judged by vision. Moreover, these effects were found to be independent of recognition performance, suggesting a dissociation between affective and cognitive processing. Our demonstration of a cross-modal mere exposure effect suggests that the affective system integrates inputs from visual and tactile modalities asymmetrically.