Crowding Effects across Depth Are Fixation-Centered for Defocused Flankers and Observer-Centered for Defocused Targets

Abstract

Depth needs to be considered to understand visual information processing in cluttered environments in the wild. Since differences in depth depend on current gaze position, eye movements were avoided by short presentations in a real depth setup. Thus, allowing only peripheral vision, crowding was tested. That is, the impairment of peripheral target recognition by the presence of nearby flankers was measured. Real depth was presented by a half-transparent mirror that aligned the displays of two orthogonally arranged, distance-adjustable screens. Fixation depth was at a distance of 190 cm, defocused depth planes were presented either near or far, in front of or behind the fixation depth, all within the depth of field. In Experiments 1 and 2, flankers were presented defocused, while the to-be-identified targets were on the fixation depth plane. In Experiments 3–5, targets were presented defocused, while the flankers were kept on the fixation depth plane. Results for defocused flankers indicate increased crowding effects with increased flanker distance from the target at focus (near to far). However, for defocused targets, crowding for targets in front of the focus as compared to behind was increased. Thus, defocused targets produce decreased crowding with increased target distance from the observer. To conclude, the effects of flankers in depth seem to be centered around fixation, while effects of target depth seem to be observer-centered.

Close - but not distant - conditioned flanker emotion affects crowding

“…closer to the observer, compared to farther away). This effect of real flanker depth replicates observer-centered result patterns of previous experiments reported by Eberhardt and Huckauf (2020) . Further, effects of emotion on crowding were replicated: in Experiment 1 a, it was investigated whether the amplifying effect of negative compared to neutral conditioned flanker emotion described by Pittino et al (2019) occurs also when flankers are defocused in depth.…”

“…The results also replicate the effect of real target depth reported by Eberhardt and Huckauf (2020) , irrespective of target emotion: stronger crowding effects were observed for targets closer compared to farther away than the fixation depth, as indicated by larger critical spacings.…”

“…Therefore, in Experiment 2 , negatively or neutrally conditioned targets were presented either close to the observer or farther away than the fixation depth, on which not-conditioned flankers were presented. Eberhardt and Huckauf (2020) showed that defocused targets are more affected by crowding when they are presented close compared to farther away from the observer. Thus, we expected larger critical spacings for close compared to far targets.…”

“…In Experiment 1 , recognition performance with a fixed target-to-flanker spacing was measured as dependent variable (similar to Eberhardt & Huckauf, 2017 ; Eberhardt & Huckauf; 2019 , Eberhardt & Huckauf; 2020 ). Each trial started self-paced with the presentation of a bright fixation cross.…”

“…With regard to distance, there have already been studies on crowding reported by Eberhardt and Huckauf (2020) . They investigated crowding effects when either targets or flankers were varied in real depth, avoiding perceptual detriments of virtual depth techniques ( Hoffman, Grishick, Akeley, & Banks, 2008 ; Kim, Kane, & Banks, 2014 ; Lambooij, Ijsselsteijn, & Heynderickx, 2007 ).…”