Abstract
Studies have shown that complex visual scenes can be categorized at the superordinate level (e.g., animal/non-animal or vehicle/non-vehicle) with minimal attentional requirements. Retrieving finer-grained information in order to perform basic-level categorization of natural scenes, such as dog/non-dog or car/non-car, requires additional processing (i.e., reaction times are longer) and might thus involve attentional processing. The attentional requirements of basic-level categorization of natural scenes were tested in the current study with a dual-task paradigm in which subjects performed the basic level categorization task either alone (single task condition) or concurrently with an attentionally demanding letter discrimination task (dual task condition). To determine whether basic level categorization can be performed outside the spatial focus of attention we compared accuracy on this task in the single task condition (when attention is available) and the dual-task condition (when attention is engaged by the letter discrimination task). If the basic-level categorization task does not require attention then performance on this task in the single and dual task conditions should be comparable. However, performance in the dual task condition should be considerably impaired if attention is necessary for successful categorization at the basic level. Our results indicate that basic-level categorization of biological (dog/non-dog) and man-made (car/non-car) stimuli can be performed remarkably well even when attention is not fully available. However, categorization at the basic level entailed longer stimulus presentation times than at the superordinate level, reflecting an increase in the amount of information required. Thus, although basic-level processing involves longer stimulus presentation durations and results in longer reaction times compared to superordinate-level processing, it can still be performed in the near-absence of attention.
‘Fyssen Foundation and BQR-Universite Paul Sabatier to L.R.