Attention, novelty preference and the visual paired comparison task.

The innate ability of humans to identify, process and ascribe greater attentional resources (attention bias) to novel stimuli is essential for exploring new opportunities and consequently adapt to changing environments. One of the most common tests to assess attention bias to novel stimuli (Novelty Preference - NP) is the visual paired comparison task (VPC). In the VPC task subjects are presented with novel and previously seen images (repeated images) and NP is measured by parameters that describe visual scanning patterns on these images. The main objective of this study is to evaluate the effects of divided attention on NP. NP was measured in 26 healthy young individuals under two test conditions. In the first condition, subjects performed the VPC task and an audio task simultaneously (divided attention test condition), while in the second condition subjects performed only the VPC task (undivided attention test condition). For each test condition, repeated images were presented after delays ranging from 1.0 to 219.5 s and NP was measured by the mean difference between the relative fixation times on novel and repeated images at each delay. In the divided attention test condition, there were significant differences (p < 0.037) between the magnitudes of NPs for long delays (≥ 162 s) and short delays (≤12.5 s). Such differences were not detected in the undivided attention test condition. Analysis of variance revealed significant differences between the measured NPs during the divided and undivided attention test conditions (F(1, 25) = 18.38, p < 0.001, η = 0.424) and significant interaction effects between delays and testing conditions (F(5,125) = 2.88, p = 0.017, η = 0.103). Post-hoc t-tests showed significant differences between the measured NPs during the divided attention and undivided attention test conditions for long delays (162.0 and 219.5 s) but not for short delays (1.0 and 12.5 s). The results of the study are consistent with the hypothesis that for longer delays between the presentations of repeated images in the VPC task, NP is dependent on the recollection-based item recognition memory system, while for shorter delays NP is dependent on the automatic, familiarity-based item recognition memory system.