No abstract

We report four experiments that tested whether object-based attentional spreading can be modulated by the perceptual structure of objects occupied by target and flankers in a flanker task. The target and flankers were presented on a single object or three separate objects (of same or different shape), displayed at fixed, known locations. The flanker compatibility effect was larger when the target and flankers were on the same object or on three objects of the same shape than when they were on three objects of different shapes, indicating that perceptual grouping of background objects occupied by target and flankers can affect the target-flanker interference. These results imply that attention likely spreads across different objects occupied by target and flankers when these objects are separated by small gaps or have identical shapes, and attentional spreading is impeded when these objects have different shapes, suggesting that object-based attentional spreading can be modulated by the perceptual structure of objects.

In this study, we investigated whether the meanings of radicals are involved in reading ideogrammic compounds in a spatial Stroop task. We found spatial Stroop effects of similar size for the simple characters [symbol: see text] ("up") and [symbol: see text] ("down") and for the complex characters [symbol: see text] ("nervous") and [symbol: see text] ("nervous"), which are ideogrammic compounds containing a radical [symbol: see text] or [symbol: see text], in Experiments 1 and 2. In Experiment 3, the spatial Stroop effects were also similar for the simple characters [symbol: see text] ("east") and [symbol: see text] ("west") and for the complex characters [symbol: see text] ("state") and [symbol: see text] ("spray"), which contain [symbol: see text] and [symbol: see text] as radicals. This outcome occurred regardless of whether the task was to identify the character (Exps. 1 and 3) or its location (Exp. 2). Thus, the spatial Stroop effect emerges in the processing of radicals just as it does for processing simple characters. This finding suggests that when reading ideogrammic compounds, (a) their radicals' meanings can be processed and (b) ideogrammic compounds have little or no influence on their radicals' semantic processing.

Task-irrelevant spatial information, conveyed by stimulus location, location word, or arrow direction, can influence the response to task-relevant attributes, generating the location-, word-, and arrow-based Simon effects. We examined whether different mechanisms are involved in the generation of these Simon effects by fitting a mathematical ex-Gaussian function to empirical response time (RT) distributions. Specifically, we tested whether which ex-Gaussian parameters (μ, σ, and τ) show Simon effects and whether the location-, word, and arrow-based effects are on different parameters. Results show that the location-based Simon effect occurred on mean RT and μ but not on τ, and a reverse Simon effect occurred on σ. In contrast, a positive word-based Simon effect was obtained on all these measures (including σ), and a positive arrow-based Simon effect was evident on mean RT, σ, and τ but not μ. The arrow-based Simon effect was not different from the word-based Simon effect on τ or σ but was on μ and mean RT. These distinct results on mean RT and ex-Gaussian parameters provide evidence that spatial information conveyed by the various location modes are different in the time-course of activation.