Academic journal article Psychonomic Bulletin & Review

Early Activation of Object Names in Visual Search

Academic journal article Psychonomic Bulletin & Review

Early Activation of Object Names in Visual Search

Article excerpt

In a visual search experiment, participants had to decide whether or not a target object was present in a four-object search array. One of these objects could be a semantically related competitor (e.g., shirt for the target trousers) or a conceptually unrelated object with the same name as the target-for example, bat (baseball) for the target bat (animal). In the control condition, the related competitor was replaced by an unrelated object. The participants' response latencies and eye movements demonstrated that the two types of related competitors had similar effects: Competitors attracted the participants' visual attention and thereby delayed positive and negative decisions. The results imply that semantic and name information associated with the objects becomes rapidly available and affects the allocation of visual attention.

In many everyday tasks (e.g., reading, driving), we must direct our visual attention to appropriate stimuli at the appropriate times. The control of visual attention has often been studied in visual search paradigms, wherein participants decide as quickly as possible whether or not a target is part of a search display. Current models of selective visual attention assume that search performance is determined by competition among visual stimuli, which is moderated by bottom-up and top-down influences (see Destinone & Duncan, 1995; Duncan & Humphreys, 1989). Top-down influences can be modulated by a "template" for the target, which can prime the representation of an object in a search display, biasing attentional selection toward it (Chelazzi, Miller, Duncan, & Destinone, 1993; Hodsoll & Humphreys, 2001, 2005; Soto, Heinke, Humphreys, & Blanco, 2005).

The working memory representation of the target will often be linked to knowledge about the object stored in long-term memory. Moores, Laiti, and Chelazzi (2003) demonstrated the existence of associative effects on the allocation of visual attention during visual search. They showed participants four-object displays that could include an associate to the target - for instance, a crash helmet when the target was a motorbike. The presence or absence of an associate did not affect the participants' response speed or accuracy on target-present trials, but on target-absent trials, they responded more slowly and less accurately when the associate was present. Eye-movement analyses showed that, on target-present and target-absent trials, the first saccade after display onset was more often directed to the associate than to an unrelated control object. On target-present trials, most initial saccades were directed to the target, but the likelihood of first saccades to the target was reduced by the presence of an associate. These findings suggest that activation spreads from targets to associatively related representations. Because of this, the related object in the display is primed and competes with the target more efficiently, relative to unrelated objects, for the allocation of visual attention (see also Dahan & Tanenhaus, 2005; Huettig & Altmann, 2005).

The long-term memory representations of most common objects are connected to lexical entries specifying their names. A lexical entry consists of a semantic-syntactic representation of a word (the lemma) and representations of its morphological and phonological form (e.g., Dell, 1986; Levelt, Roelofs, & Meyer, 1999). Several studies have shown that names of common objects become rapidly activated even when the objects are presented extra-foveally (e.g., Morgan & Meyer, 2005) and when speakers do not intend to name them, but plan to name other simultaneously present objects (Meyer & Damian, 2007; Morsella & Miozzo, 2002; Navarette & Costa, 2005). However, in all of these studies, participants were engaged in naming tasks. It is as yet unclear whether lexical representations become activated in search as well and influence competition with the target for selection. …

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