Purchase this article with an account.
Li Jingling, Li Zhaoping; Contribution of location uncertainty and feature similarity to illusory conjunction of basic visual features under limited attention. Journal of Vision 2007;7(9):644. doi: 10.1167/7.9.644.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
We explore contributing factors to illusory conjunction (IC) of basic features under limited attention. Subjects were briefly shown two bars, horizontally next to each other, of different colors, different orientations and moving in different directions. These bars were horizontally flanked by two stationary, colorless, ‘S’ symbols, and presented at 5.76° eccentricity at randomly one of four possible corners of the display. Subjects had to (1) name a currently presented digit at fixation, and (2), report the feature value of a target bar (among the two bars) in a given feature dimension, which was either color, or orientation, or motion direction, and is termed the reporting feature dimension. The target bar was defined as the one having the color, or orientation, or motion direction (called the target defining feature) indicated by a subsequently presented central stimulus. In each experimental session, the reporting feature dimension was fixed and had four possible feature values; the defining feature dimension randomly varied between the two other feature dimensions. Each defining feature dimension had two feature values, one for each bar. Subjects reported the features either correctly, or erroneously reporting the feature of the non-target bar (conjunction error, CE) or an absent feature value (feature error, FE). Using FE rates to remove the contribution of guessing to CE rates, we calculated the IC rates. We found that, given a defining feature, regardless of its feature dimension, IC rates increased with the error rates of reporting the target position (left or right of the two bars), probed in another experiment (using the same stimuli, digit naming task, and the target defining procedure, for the same subjects). Since target position errors were found to increase with feature similarities in the defining feature dimension, different previous explanations to IC could be reconciled (Donk 1999, Ashby et al 1996).
This PDF is available to Subscribers Only