Abstract
Research has shown that when searching for information in a web-based menu people do not always scan every item (e.g. Pierce, Parkinson & Sisson 1992; Brumby and Howes, 2003, 2004). Furthermore, this behaviour has been attributed to the pattern of relevance of the items in the menu with regards to a pre-specified task goal.
We report an experiment to test whether the number of items skipped depends on the semantic quality of the alternative items and found that as more alternatives compete with the target for selection, less items are skipped. This behaviour was emphasised when the target was positioned towards the top of the menu. This suggests that when alternative items are perceived as unlikely to lead to task completion, people develop a scanning strategy that allows for more cost-effective searches. This is in accordance with a priori predictions made by a computational model for single-page menu search based on rational analysis (Cox and Young, 2004). The results of a forced-choice recognition task demonstrated that parafoveal processing of items occurred during scanning of the menu which could account for the lack of fixations on items.
However, in a second experiment, parafoveal processing was eliminated by increasing inter-item distance, and in this case, fewer items were skipped, suggesting that parafoveal processing accounts for part of the skipping behaviour. An extension of the initial rational model is proposed to explain the results.