Perceptual target discriminability modulates the Simon effect beyond the fading of distractor-based activation: Insights from delta plots and diffusion model analyses.

The visual Simon task is widely employed to explore the underlying mechanisms of sensorimotor processing in the presence of task-relevant (targets) and task-irrelevant (distracting) location information. Critically, the Simon effect is considered as an indicator of action-related interference resulting from distractor-based activation, which fades out over time. In this study, we tested whether attenuated Simon effects with slower task processing may be fully explained by the fading of distractor-based response activation. To that end, we selectively manipulated perceptual target discriminability by varying the ratio of differently colored dots within (Experiment 1) and between blocks (Experiment 2). According to pure fading activation accounts, the negative-going delta plots of the two discriminability conditions should overlap across the entire reaction time (RT) distribution. In contrast to this prediction, the negative-going DPs for the two discriminability conditions did not overlap in either experiment. Instead, the Simon effect was either consistently smaller (Experiment 1) or larger (Experiment 2) across the entire RT distribution in the easy condition compared to the hard condition. This result pattern indicates that perceptual target discriminability affected conflict resolution beyond the mere fading of distractor-based activation. Exploratory model-based analyses suggest a stronger processing of relevant perceptual information with more discriminable targets, which may counteract the influence of distracting location information. However, as the exact effects of discriminability on conflict processing seem to depend on variation mode (trialwise vs. blockwise), the importance of global strategic effects is also highlighted. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Order effects in stimulus discrimination challenge established models of comparative judgement: A meta-analytic review of the Type B effect.

This paper provides a comprehensive review of the Type B effect (TBE), a phenomenon reflected in the observation that discrimination sensitivity varies with the order of stimuli in comparative judgment tasks, such as the two-alternative forced-choice (2AFC) paradigm. Specifically, when the difference threshold is lower (higher) with the constant standard preceding rather than following the variable comparison, one speaks of a negative (positive) TBE. Importantly, prominent psychophysical difference models such as signal detection theory (Green & Swets, 1966) cannot easily account for the TBE, and are hence challenged by it. The present meta-analysis provides substantial evidence for the TBE across various stimulus attributes, suggesting that the TBE is a general feature of discrimination experiments when standard and comparison are presented successively. Thus, inconsistent with psychophysical difference models, subjective differences between stimuli are not merely a function of their physical differences but rather also depend on their temporal order. From the literature, we identify four classes of potential candidate theories explaining the origin of the TBE, namely (1) differential weighting of the stimulus magnitudes at the two positions (e.g., Hellström, Psychological Research, 39, 345-388 1977), (2) internal reference formation (e.g., Dyjas, Bausenhart, & Ulrich, Attention, Perception, & Psychophysics, 74, 1819-1841 2012), (3) Bayesian updating (e.g., de Jong, Akyürek, & van Rijn, Psychonomic Bulletin and Review, 28, 1183-1190 2021), and (4) biased threshold estimation (García-Pérez & Alcalá-Quintana, Attention, Perception & Psychophysics, 72, 1155-1178 2010). As these models, to some extent, make differential predictions about the direction of the TBE, investigating the respective boundary conditions of positive and negative TBEs might be a valuable perspective for diagnostic future research.

Opposing influences of global and local stimulus-hand proximity on crosstalk interference in dual tasks.

In contrast to traditional dualistic views of cognition, visual stimulus processing appears not independent of bodily factors such as hand positioning. For example, reduced crosstalk between two temporally overlapping tasks has been observed when the hands are moved into the attentional window alongside their respective stimuli (i.e., establishing global stimulus-hand proximity). This result indicates that hand-specific attentional processing enhancements support a more serial rather than parallel processing of the two tasks. To further elucidate the nature of these processing modulations and their effect on multitasking performance, the present study consisted of three interrelated crosstalk experiments. Experiment 1 manipulated global stimulus-hand proximity and stimulus-effect proximity orthogonally, with results demonstrating that hand proximity rather than effect proximity drives the crosstalk reduction. Experiment 2 manipulated the physical distance between both hands (i.e., varying local stimulus-hand proximity), with results showing weak evidence of increased crosstalk when both hands are close to each other. Experiment 3 tested opposing influences of global and local stimulus-hand proximity as observed in Experiment 1 and 2 rigorously within one experiment, by employing an orthogonal manipulation of these two proximity measures. Again, we observed slightly increased crosstalk for hands close to each other (replicating Experiment 2); however, in contrast to Experiment 1, the effect of global stimulus-hand proximity on the observed crosstalk was not significant this time. Taken together, the experiments support the notion of hand-specific modulations of perception-action coupling, which can either lead to more or less interference in multitasking, depending on the exact arrangement of hands and stimuli.

Decay of internal reference information in duration discrimination: Intertrial interval modulates the Type B effect.

Psychophysical evidence suggests that human perception of a stimulus is assimilated towards previous stimuli. The internal reference model (IRM) explains such assimilation through an internal reference (IR), which integrates past and present stimulus representations and thus might be conceived as a form of perceptual memory. In this study, we investigated whether the IR decays with time, as previously shown for perceptual memory representations in general. One specific prediction of IRM is higher discrimination sensitivity when a constant standard precedes rather than follows a variable comparison in a two-alternative forced-choice (2AFC) discrimination task. Furthermore, the magnitude of this so-called negative Type B effect should decrease with decreasing weighting of past stimulus information in the integration process. Therefore, decay of the IR should result in a reduced Type B effect. To examine this prediction, we carried out a 2AFC duration discrimination experiment with a short (1,600 ms) and a long (3,200 ms) intertrial interval (ITI). As expected, a reduced negative Type B effect was observed at the long compared with the short ITI, consistent with the idea that humans rely on the immediate past when evaluating current sensory input, however, less so when the IR incorporating the perceptual short-term memory representation of these past stimuli has already decayed.

Effects of stimulus order on comparative judgments across stimulus attributes and sensory modalities.

In psychophysical experiments, participants are often asked to compare the magnitude of a constant standard against the magnitude of a variable comparison. According to prominent models of stimulus discrimination, discrimination sensitivity should depend only on the physical magnitude difference between these two stimuli but not on the order of their presentation. However, previous experiments on auditory duration discrimination have shown that discrimination sensitivity is higher when the standard precedes rather than follows the comparison. It is presently unclear whether this Type B effect emerges only for duration discrimination or generalizes across modalities and stimulus attributes. Therefore, we conducted a study in which participants performed several discrimination tasks for various stimulus attributes (i.e., duration, frequency, intensity, and numerosity), each in the visual and in the auditory modality. In all cases, discrimination sensitivity was higher when the standard preceded rather than followed the comparison. This result indicates that the Type B effect is not restricted to the domain of temporal cognition but rather reflects a general phenomenon across a range of domains and modalities. The outcome of the present experiment is consistent with the internal reference model according to which the Type B effect is a consequence of a dynamically updated internal reference, which is used in the comparison process. Alternatively, a weighted difference model with a larger weight for the second stimulus position than for the first stimulus position can also account for this result. (PsycINFO Database Record

On the time-course of automatic response activation in the Simon task.

The Simon effect (prolonged RT when the task-irrelevant stimulus location is incongruent with the response side) has been reported to decrease at longer RTs, which is reflected in negative-going delta functions. This finding has been attributed to gradual dissipation of the response automatically activated by the task-irrelevant location information. The Diffusion Model for Conflict Tasks (DMC, Ulrich, Schröter, Leuthold, & Birngruber, Cognitive Psychology 78:148-174, 2015) formally specifies the time-course of this automatic activation process as a pulse-like function. In contrast to alternative views, DMC is consistent with the notion that this time-course is unaffected by the presentation duration of the target stimulus. Therefore, we expected that delta functions are invariant against changes of stimulus duration. This prediction was verified in two Simon task experiments. Consistent with this general result, DMC's parameter τ which defines the time-course of the automatic response activation was estimated to not meaningfully differ between short and long durations. We argue that our results are coherent with processing architectures that assume a transient automatic process that is virtually unaffected by stimulus duration.

Delta plots with negative-going slopes as a potential marker of decreasing response activation in masked semantic priming.

Delta plots with negative-going slopes (nDPs) reflect the phenomenon that an RT difference between two conditions is greater for relatively fast than for relatively slow responses. This unusual distributional pattern has predominantly been observed in the spatial Simon task, where it has been interpreted as reflecting the selective inhibition of an automatically activated response. The literature suggesting that a similar fading mechanism influences RTs in masked identity priming inspired us to check an analogous semantic priming paradigm for nDPs. Consistent with the findings in other paradigms, two masked semantic priming experiments revealed stronger priming effects for relatively fast than for relatively slow responses, thus reflecting an nDP. These findings are compatible with the ideas that the activation produced by masked semantic primes decreases over the course of a trial, such as that of irrelevant spatial information and of masked identity primes, and that nDPs are a general signature of within-trial decreases in response activation across different tasks and paradigms.