Abstract
It is well established that, in visual pop-out search, reaction time (RT) performance is influenced by cross-trial repetitions versus changes of target-defining attributes. One instance of this is referred to as “positional priming of pop-out” (pPoP; Maljkovic and Nakayama, 1996). In positional PoP paradigms, the processing of the current target is examined depending on whether it occurs at the previous target or a previous distractor location, relative to a previously empty location (“neutral” baseline), permitting target facilitation and distractor inhibition to be dissociated. The present study combined RT measures with specific sensory- and motor-driven event-related lateralizations to track the time course of four distinct processing levels as a function of the target’s position across consecutive trials. The results showed that, relative to targets at previous target and “neutral” locations, the appearance of a target at a previous distractor location was associated with a delayed build-up of the posterior contralateral negativity wave, indicating that distractor positions are suppressed at early stages of visual processing. By contrast, presentation of a target at a previous target, relative to “neutral” and distractor locations, modulated the elicitation of the subsequent stimulus-locked lateralized readiness potential wave, indicating that post-selective response selection is facilitated if the target occurred at the same position as on the previous trial. Overall, the results of present study provide electrophysiological evidence for the idea that target location priming (RT benefits) does not originate from an enhanced coding of target saliency at repeated (target) locations; instead, they arise (near-) exclusively from processing levels subsequent to focal-attentional target selection.
Highlights
BEHAVIORAL DATA Error rates There was a main effect of target position sequence on accuracy [F(2,26) = 8.86, p < 0.01]: error rates being lowest for targets presented at the previous target location, intermediate for targets at a previously neutral location, and highest for targets at a previous distractor location (7 vs. 8 vs. 9%; all p values < 0.05; Figure 2)
The interaction was due to the fact that the benefits for repeated target locations were more marked when participants had to produce the same response, as compared to a different response, as on the previous trial (44 vs. 7 msec; p < 0.001)
NO PRIMING OF POP-OUT FOR REPEATED TARGET LOCATIONS The most striking finding was exhibited by the posterior contralateral negativity (PCN) wave—a well established and generally agreed event-related potential (ERP) marker of focalattentional selection of task-relevant target items (e.g., Eimer, 1996; Woodman and Luck, 1999; Töllner et al, 2012a)—which was significantly slowed for targets presented at previous distractor locations relative to both targets presented at previous neutral and targets at previous target locations3
Summary
INTER-TRIAL PRIMING EFFECTS Visual search performance on a given trial is determined by the currently active top-down and bottom-up biases (e.g., Corbetta and Shulman, 2002), and through sensory and motor-related events that occurred on the previous trial(s) – a class of memory effects commonly referred to as “inter-trial priming.” Over the last two decades, a number of target attributes have been revealed to selectively, or interactively, contribute to intertrial priming, including stimulus positions (e.g., Maljkovic and Nakayama, 1996; Geyer et al, 2007), stimulus features (e.g., Maljkovic and Nakayama, 1994; Kristjánsson and Driver, 2008), visual dimensions (e.g., Müller et al, 1995; Found and Müller, 1996), sensory modalities (e.g., Spence et al, 2001; Töllner et al, 2009), objects (e.g., Kristjánsson et al, 2008), motor responses (e.g., Töllner et al, 2008), as well as components of the task set adopted by participants to optimize performance (e.g., Rangelov et al, 2011, 2013). Over the last two decades, a number of target attributes have been revealed to selectively, or interactively, contribute to intertrial priming, including stimulus positions (e.g., Maljkovic and Nakayama, 1996; Geyer et al, 2007), stimulus features (e.g., Maljkovic and Nakayama, 1994; Kristjánsson and Driver, 2008), visual dimensions (e.g., Müller et al, 1995; Found and Müller, 1996), sensory modalities (e.g., Spence et al, 2001; Töllner et al, 2009), objects (e.g., Kristjánsson et al, 2008), motor responses (e.g., Töllner et al, 2008), as well as components of the task set adopted by participants to optimize performance (e.g., Rangelov et al, 2011, 2013). According to the “pre-attentive” view, inter-trial priming facilitates early sensory processes, such as the selection of the target by focal attention (e.g., Maljkovic and Nakayama, 2000; Goolsby and Suzuki, 2001; Müller et al, 2003, 2010; Wolfe et al, 2003; Meeter and Olivers, 2014). Töllner et al (2008) investigated the locus of dimension and response priming effects in visual search www.frontiersin.org
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