Sharing the Spotlight: Evidence that Hemifield Independence is a Unique Trait of Spatial-based Attention
Presentation Type
Paper
Abstract
Research has found evidence supporting a two spotlight model of spatial-based attention, but only a single spotlight model for feature-based attention in visual search. Specifically, participants are faster at finding a peripheral target when a search array is displayed across both visual fields as opposed to only one. However, closer scrutiny of findings reveal a number of potential confounds that hemi-specific attentional frameworks have not definitively characterized, including impacts of distractor filtering, array previews, and spatial certainty. Here, participants searched for a target “T” among distractor “L’s” distributed unilaterally or bilaterally across three eccentricities in a half circle above the midline of the display. For feature-based searches, participants were told to attend to only white items; spatial-based participants were told to only search the middle eccentricity. In experiment 1, we found that the presence of a distractor “T” at non-attended target eccentricities during spatial search did not impact performance. Surprisingly, hemifield effects were found for both search types. In experiment 2, we manipulated whether participants received a masked preview of the array locations and found a hemifield advantage only for spatial-based search. In experiment 3, we varied the spatial certainty of the feature-based target and found evidence of a hemifield effect only for spatial-based search. Combined, these data are consistent with previous suggestions that spatial-based attention is exclusively subserved by hemifield independent mechanisms, a characteristic that could have implications for facilitating information processing in complex tasks.
Sharing the Spotlight: Evidence that Hemifield Independence is a Unique Trait of Spatial-based Attention
Research has found evidence supporting a two spotlight model of spatial-based attention, but only a single spotlight model for feature-based attention in visual search. Specifically, participants are faster at finding a peripheral target when a search array is displayed across both visual fields as opposed to only one. However, closer scrutiny of findings reveal a number of potential confounds that hemi-specific attentional frameworks have not definitively characterized, including impacts of distractor filtering, array previews, and spatial certainty. Here, participants searched for a target “T” among distractor “L’s” distributed unilaterally or bilaterally across three eccentricities in a half circle above the midline of the display. For feature-based searches, participants were told to attend to only white items; spatial-based participants were told to only search the middle eccentricity. In experiment 1, we found that the presence of a distractor “T” at non-attended target eccentricities during spatial search did not impact performance. Surprisingly, hemifield effects were found for both search types. In experiment 2, we manipulated whether participants received a masked preview of the array locations and found a hemifield advantage only for spatial-based search. In experiment 3, we varied the spatial certainty of the feature-based target and found evidence of a hemifield effect only for spatial-based search. Combined, these data are consistent with previous suggestions that spatial-based attention is exclusively subserved by hemifield independent mechanisms, a characteristic that could have implications for facilitating information processing in complex tasks.