Analyzing distributional properties of interference effects across modalities: chances and challenges.

In research investigating Stroop or Simon effects, data are typically analyzed at the level of mean response time (RT), with results showing faster responses for compatible than for incompatible trials. However, this analysis provides only limited information as it glosses over the shape of the RT distributions and how they may differ across tasks and experimental conditions. These limitations have encouraged the analysis of RT distributions using delta plots. In the present review, we aim to bring together research on distributional properties of auditory and visual interference effects. Extending previous reviews on distributional properties of the Simon effect, we additionally review studies reporting distributional analyses of Stroop effects. We show that distributional analyses of sequential effects (i.e., taking into account congruency of the previous trial) capture important similarities and differences of interference effects across tasks (Simon, Stroop) as well as across sensory modalities, despite some challenges associated to this approach.

Does ignoring lead to worse evaluations? A new explanation of the stimulus devaluation effect.

Affective evaluation of stimuli just seen in visual search tasks has been shown to depend on task-relevant stimulus configuration (Raymond, Fenske, & Tavassoli, 2003): Whereas targets and novel stimuli were evaluated similarly, distractors were devaluated. These results were explained by an inhibition-based account of the influence of selective attention on emotion. In the present experiments, we demonstrated that stimulus devaluation might not be a consequence of attentional inhibition. By simply instructing participants to react to an accepted or rejected stimulus in the visual search task of Experiment 1, we found distractor devaluation in the first case and target devaluation in the second case. We conclude that devaluation of stimuli is mediated by the affective connotation implied by response labels and instructions. This was confirmed in Experiment 2: To-be-ignored stimuli were not devaluated when participants knew that those stimuli would become task-relevant during the experiment.

How vertical elevation affects self-other integration as measured by the joint Simon effect.

Earlier findings suggest that positions of power decrease self-other integration and increase psychological distance to others. Until now, however, evidence for this relation rests exclusively on subjective measures. The current research instead employed a vertical joint Simon task to measure self-other integration. This task assesses the extent to which people represent their own actions in reference to their co-actor's, also referred to as the joint Simon effect. Building on cultural associations between power and vertical elevation, we manipulated whether participants were in an elevated (high-power) or lower (low-power) seating position. Experiments 1a and 1b reanalyzed existing datasets and found that elevated (vs. lower) seating position decreased the joint Simon effect, consistent with predictions. Experiment 2 provides a high-powered replication of this finding. Yet, further analyses revealed that feelings of power - measured as a manipulation check and indeed demonstrating that the manipulation was successful - did not mediate or moderate the effect of seating position on the joint Simon effect. Therefore, it is possible that the effect of seating elevation was driven through other aspects of that manipulation than feelings of power. We discuss these and suggest ways to test these alternative explanations.

A comparison of the temporal weighting of annoyance and loudness.

The influence of single temporal portions of a sound on global annoyance and loudness judgments was measured using perceptual weight analysis. The stimuli were 900-ms noise samples randomly changing in level every 100 ms. For loudness judgments, Pedersen and Ellermeier [J. Acoust. Soc. Am. 123, 963-972 (2008)] found that listeners attach greater weight to the beginning and ending than to the middle of a stimulus. Qualitatively similar weights were expected for annoyance. Annoyance and loudness judgments were obtained from 12 listeners in a two-interval forced-choice task. The results demonstrated a primacy effect for the temporal weighting of both annoyance and loudness. However, a significant recency effect was observed only for annoyance. Potential explanations of these weighting patterns are discussed. Goodness-of-fit analysis showed that the prediction of annoyance and loudness can be improved by allowing a non-uniform weighting of single temporal portions of the signal, rather than assuming a uniform weighting as in measures like the energy-equivalent level (L(eq)). A second experiment confirmed that the listeners were capable of separating annoyance and loudness of the stimuli. Noises with the same L(eq) but different amplitude modulation depths were judged to differ in annoyance but not in loudness.

Two distinct patterns of interference in between-attribute Stroop matching tasks.

In between-attribute Stroop matching tasks, participants compare the meaning (or the color) of a Stroop stimulus with a probe color (or meaning) while attempting to ignore the Stroop stimulus's task-irrelevant attribute. Interference in this task has been explained by two competing theories: A semantic competition account and a response competition account. Recent results favor the response competition account, which assumes that interference is caused by a task-irrelevant comparison. However, the comparison of studies is complicated by the lack of a consensus on how trial types should be classified and analyzed. In this work, we review existing findings and theories and provide a new classification of trial types. We report two experiments that demonstrate the superiority of the response competition account in explaining the basic pattern of performance while also revealing its limitations. Two qualitatively distinct interference patterns are identified, resulting from different types of task-irrelevant comparisons. By finding the same interference pattern across task versions, we were additionally able to demonstrate the comparability of processes across two task versions frequently used in neurophysiological and cognitive studies. An integrated account of both types of interference is presented and discussed.

The influence of the Japanese waving cat on the joint spatial compatibility effect: A replication and extension of Dolk, Hommel, Prinz, and Liepelt (2013).

In a joint go/no-go Simon task, each of two participants is to respond to one of two non-spatial stimulus features by means of a spatially lateralized response. Stimulus position varies horizontally and responses are faster and more accurate when response side and stimulus position match (compatible trial) than when they mismatch (incompatible trial), defining the social Simon effect or joint spatial compatibility effect. This effect was originally explained in terms of action/task co-representation, assuming that the co-actor's action is automatically co-represented. Recent research by Dolk, Hommel, Prinz, and Liepelt (2013) challenged this account by demonstrating joint spatial compatibility effects in a task-setting in which non-social objects like a Japanese waving cat were present, but no real co-actor. They postulated that every sufficiently salient object induces joint spatial compatibility effects. However, what makes an object sufficiently salient is so far not well defined. To scrutinize this open question, the current study manipulated auditory and/or visual attention-attracting cues of a Japanese waving cat within an auditory (Experiment 1) and a visual joint go/no-go Simon task (Experiment 2). Results revealed that joint spatial compatibility effects only occurred in an auditory Simon task when the cat provided auditory cues while no joint spatial compatibility effects were found in a visual Simon task. This demonstrates that it is not the sufficiently salient object alone that leads to joint spatial compatibility effects but instead, a complex interaction between features of the object and the stimulus material of the joint go/no-go Simon task.

You Are Right!

In the social Simon task, two participants perform a spatial compatibility task together, each of them responding to only one stimulus (e.g., one participant reacts to red, the other to green stimuli). Participants show joint spatial compatibility effects (SCEs), that is, they respond faster when their go-stimulus appears on their half of the screen. Effects are absent when the same go/no-go task is performed without a coactor. Joint SCEs were originally explained in terms of shared task representations, but recent research suggests that effects result from spatial response coding: in joint go/no-go tasks, participants perceive themselves as the right/left participant operating a right/left response key. While previous research showed that the spatial alignment of keys and seats influences the effect, the present research demonstrates that merely instructing participants to be the right/left participant operating a right/left response key instead of labeling participants and keys with arbitrary numbers substantially increases joint SCEs.

The joint flanker effect and the joint Simon effect: On the comparability of processes underlying joint compatibility effects.

Previous studies observed compatibility effects in different interference paradigms such as the Simon and flanker task even when the task was distributed across two co-actors. In both Simon and flanker tasks, performance is improved in compatible trials relative to incompatible trials if one actor works on the task alone as well as if two co-actors share the task. These findings have been taken to indicate that actors automatically co-represent their co-actor's task. However, recent research on the joint Simon and joint flanker effect suggests alternative non-social interpretations. To which degree both joint effects are driven by the same underlying processes is the question of the present study, and it was scrutinized by manipulating the visibility of the co-actor. While the joint Simon effect was not affected by the visibility of the co-actor, the joint flanker effect was reduced when participants did not see their co-actors but knew where the co-actors were seated. These findings provide further evidence for a spatial interpretation of the joint Simon effect. In contrast to recent claims, however, we propose a new explanation of the joint flanker effect that attributes the effect to an impairment in the focusing of spatial attention contingent on the visibility of the co-actor.

The invariance assumption in process-dissociation models: an evaluation across three domains.

The class of process-dissociation models, a subset of the class of multinomial processing-tree models, is one of the best understood classes of models used in experimental psychology. A number of prominent debates have addressed fundamental assumptions of process-dissociation models, leading, in many cases, to conceptual clarifications and extended models that address identified issues. One issue that has so far defied empirical clarification is how to evaluate the invariance assumption for the dominant process. Violations of the invariance assumption have, however, the potential to bias conventional process-dissociation analyses in different ways, and they can cause misleading theoretical interpretations and conclusions. Based on recent advances in multinomial modeling, we propose new approaches to examine the invariance assumption empirically and apply them in 6 studies to 3 prominent fields of application of process-dissociation models: to the Stroop task, to the interplay of recollection and habit in cued recall, and to the study of racial bias in the weapon task. In each of these content domains, the invariance assumption is found to be violated to a considerable extent.

Keys and seats: Spatial response coding underlying the joint spatial compatibility effect.

Spatial compatibility effects (SCEs) are typically observed when participants have to execute spatially defined responses to nonspatial stimulus features (e.g., the color red or green) that randomly appear to the left and the right. Whereas a spatial correspondence of stimulus and response features facilitates response execution, a noncorrespondence impairs task performance. Interestingly, the SCE is drastically reduced when a single participant responds to one stimulus feature (e.g., green) by operating only one response key (individual go/no-go task), whereas a full-blown SCE is observed when the task is distributed between two participants (joint go/no-go task). This joint SCE (a.k.a. the social Simon effect) has previously been explained by action/task co-representation, whereas alternative accounts ascribe joint SCEs to spatial components inherent in joint go/no-go tasks that allow participants to code their responses spatially. Although increasing evidence supports the idea that spatial rather than social aspects are responsible for joint SCEs emerging, it is still unclear to which component(s) the spatial coding refers to: the spatial orientation of response keys, the spatial orientation of responding agents, or both. By varying the spatial orientation of the responding agents (Exp. 1) and of the response keys (Exp. 2), independent of the spatial orientation of the stimuli, in the present study we found joint SCEs only when both the seating and the response key alignment matched the stimulus alignment. These results provide evidence that spatial response coding refers not only to the response key arrangement, but also to the-often neglected-spatial orientation of the responding agents.

Selective impairment of auditory selective attention under concurrent cognitive load.

Load theory predicts that concurrent cognitive load impairs selective attention. For visual stimuli, it has been shown that this impairment can be selective: Distraction was specifically increased when the stimulus material used in the cognitive load task matches that of the selective attention task. Here, we report four experiments that demonstrate such selective load effects for auditory selective attention. The effect of two different cognitive load tasks on two different auditory Stroop tasks was examined, and selective load effects were observed: Interference in a nonverbal-auditory Stroop task was increased under concurrent nonverbal-auditory cognitive load (compared with a no-load condition), but not under concurrent verbal-auditory cognitive load. By contrast, interference in a verbal-auditory Stroop task was increased under concurrent verbal-auditory cognitive load but not under nonverbal-auditory cognitive load. This double-dissociation pattern suggests the existence of different and separable verbal and nonverbal processing resources in the auditory domain.

Increased spatial salience in the social Simon task: a response-coding account of spatial compatibility effects.

A spatial compatibility effect (SCE) is typically observed in forced two-choice tasks in which a spatially defined response (e.g., pressing a left vs. a right key) has to be executed to a nonspatial feature of a stimulus (e.g., discriminating red from green) that is additionally connoted by a spatial feature (e.g., the stimulus points to the left or the right). Responses are faster and more accurate when the response side and the spatial stimulus feature are compatible than when they are incompatible. Previous research has demonstrated that SCEs are diminished when stimuli from only one response category are responded to in individual go/no-go tasks, whereas SCEs reemerge when two participants work jointly on two complementary, individual go/no-go tasks in a joint go/no-go task setting. This social Simon effect has been considered evidence for shared task representations. We show that SCEs emerge in individual go/no-go tasks when the spatial dimension is made more salient, whereas SCEs are eliminated in joint go/no-go tasks when the spatial dimension is made less salient. These findings are consistent with an account of social Simon effects in terms of spatial response coding, whereas they are inconsistent with an account of shared task representations. The relevance of social factors for spatial response coding is discussed.

Nonconcurrently presented auditory tones reduce distraction.

Recent research has demonstrated that task-irrelevant stimuli presented simultaneously with a target-distractor stimulus reduce distraction and improve selective attention. In studies examining this reduced interference effect, visual selective attention tasks and concurrently presented task-irrelevant stimuli are used. We report first evidence for a similar effect in the auditory domain and with nonconcurrent stimuli (i.e., the task-irrelevant stimuli are presented before the target). The effect of nonconcurrently presented auditory tones on an auditory Stroop task developed by Leboe and Mondor (Psychological Research, 71, 568--575, 2007) was investigated. Stroop interference was reduced when task-irrelevant tones were presented before the Stroop stimulus. We conclude that task-irrelevant stimuli can improve selective attention not only when presented concurrently, but also when presented before the selective attention task. Our results are consistent with the hypothesis that interference reduction is due to perceptual dilution caused by task-irrelevant stimuli.

From sunshine to double arrows: an evaluation window account of negative compatibility effects.

In category priming, target stimuli are to be sorted into 2 categories. Prime stimuli preceding targets typically facilitate processing of targets when primes and targets are members of the same category, relative to the case in which both stem from different categories, a positive compatibility effect (PCE). But negative compatibility effects (NCEs) are also sometimes observed. An evaluation window account (Klauer, Teige-Mocigemba, & Spruyt, 2009) of PCE and NCE in evaluative priming (category good versus category bad) is applied to masked arrow priming (Eimer & Schlaghecken, 1998; category left versus category right). Key principles of the account are that participants evaluate incoming evidence across a time window, and decisions about stimulus category are driven by changes in evidence weighted according to the Weber-Fechner law, leading to NCE for primes falling outside the time window and PCE for primes inside the time window. In Experiments 1-4, factors considered obligatory for NCE by current accounts of arrow priming are successively removed; yet, NCE remained intact as predicted by the evaluation window account. Furthermore, the evaluation window account, but none of the current accounts, predicts NCE without a stimulus intervening between prime and target at intermediate prime-target stimulus-onset asynchrony (Experiment 5) and when target onset comes as a surprise (Experiment 6). We conclude that the evaluation window account describes a hitherto overlooked mechanism that contributes to PCE and NCE in arrow priming and that it appears to generalize beyond the confines of evaluative priming to the diverse class of category-priming paradigms.