A reassessment of the pseudoneglect effect: Attention allocation systems are selectively engaged by semantic and spatial processing

Abstract

Healthy individuals display systematic inaccuracies when allocating attention to perceptual space. Under many conditions, optimized spatial attention processing of the right hemisphere's frontoparietal attention network directs more attention to the left side of perceptual space than the right. This is the pseudoneglect effect. We present evidence reshaping our fundamental understanding of this neural mechanism. We describe a previously unrecognized, but reliable, attention bias to the right side of perceptual space that is associated with semantic object processing. Using an object bisection task, we revealed a significant rightward bias distinct from the leftward bias elicited by the traditional line bisection task. In Experiment 2, object-like shapes that were not easily recognizable exhibited an attention bias between that of horizontal lines and objects. Our results support our proposal that the rightward attention bias is a product of semantic processing and its lateralization in the left hemisphere. In Experiment 3, our novel object-based adaptation of the landmark task further supported this proposition and revealed temporal dynamics of the effect. This research provides novel and crucial insight into the systems supporting intricate and complex attention allocation and provides impetus for a shift toward studying attention in ways that increasingly reflect our complex environments. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Figure 1. Example Objects and Lines Used in Experiment 1

Note. (A) An example object employed in the object bisection task. (B) A typical pseudoneglect-like response illustrated on a 160-pixel line. (C) The eight-line length types (20, 40, 60, 80, 100, 120, 140, and 160) assessed in the line bisection task with accurate central bisections.

Figure 2. Four Examples of Shapes Employed in the Object-Like Abstract Shape Bisection Task

Figure 3. A Summary of Data From the Object and Line Bisection Tasks in Experiment 1

Note. (A) An illustration of the mean bisection errors of the line and object bisection tasks. We observed a significant difference between the direction of the mean bisection errors associated with lines and objects (all line lengths***, shortest lines*). In addition, object bisection errors were bisected significantly to the right of the objects’ center*. (B) An illustration of the significant association between greater line lengths and increasingly leftward bisection errors*. (C) An illustration of the significant** relationship between the object asymmetry and bisection errors. Objects with right > left displayed more rightward bisection errors. Conversely, objects with left > right displayed more leftward bisection errors. Negative bisection errors depict leftward bisection errors, and positive bisection errors depict rightward bisection errors. * p < .05. ** p < .01. *** p < .001.

Figure 4. A Summary of Data From the Object-Like Abstract Shape Bisection Task in Experiment 2

Note. (A) We observed shape bisection errors that were not significantly different from center or all line lengths but were significantly rightward of lines of a similar length to the shapes*. (B) An illustration of the significant*** relationship between object asymmetry and bisection errors. Shapes with right > left displayed more rightward bisection errors. Conversely, shapes with left > right displayed more leftward bisection errors. Negative bisection errors depict leftward bisection errors, and positive bisection errors depict rightward bisection errors. * p < .05. *** p < .001.

Figure 5. Examples of Stimuli That Were Presented in the Object–Landmark Task

Note. Participants were asked to indicate whether the vertical line was in the center of the object or positioned to the left or right of center.

Figure 6. A Summary of Data From the Object-Based Adaptation of the Landmark Task in Experiment 3

Note. (A) We observed significantly* greater accuracy for identification of left transected than right transected objects. (B) We observed significant increases in accuracy accompanying greater transection divergences from center***. (C) An illustration of the significant* three-way interaction characterizing RTs. Note the significant* difference between the transection divergence slopes associated with left and right transected objects in the free viewing condition. This difference was not evident in the covert condition. The transection divergence slopes of right transected objects across the free and covert conditions were also significantly* different. This difference was not observed for left transected objects. Error bars represent one standard error. * p < .05. *** p < .001.