Brittney Hartle

Optimal combination of illusory and luminance-defined 3-D surfaces: A role for ambiguity

The shape of the illusory surface in stereoscopic Kanizsa figures is determined by the interpolation of depth from the luminance edges of adjacent inducing elements. Despite ambiguity in the position of illusory boundaries, observers reliably perceive a coherent three-dimensional (3-D) surface. However, this ambiguity may contribute additional uncertainty to the depth percept beyond what is expected from measurement noise alone. We evaluated the intrinsic ambiguity of illusory boundaries by using a cue-combination paradigm to measure the reliability of depth percepts elicited by stereoscopic illusory surfaces. We assessed the accuracy and precision of depth percepts using 3-D Kanizsa figures relative to luminance-defined surfaces. The location of the surface peak was defined by illusory boundaries, luminance-defined edges, or both. Accuracy and precision were assessed using a depth-discrimination paradigm. A maximum likelihood linear cue combination model was used to evaluate the relative contribution of illusory and luminance-defined signals to the perceived depth of the combined surface. Our analysis showed that the standard deviation of depth estimates was consistent with an optimal cue combination model, but the points of subjective equality indicated that observers consistently underweighted the contribution of illusory boundaries. This systematic underweighting may reflect a combination rule that attributes additional intrinsic ambiguity to the location of the illusory boundary. Although previous studies show that illusory and luminance-defined contours share many perceptual similarities, our model suggests that ambiguity plays a larger role in the perceptual representation of illusory contours than of luminance-defined contours.

Disparity configuration influences depth discrimination in naïve adults, but not in children

HighlightsNaïve adults cannot judge relative depth in a dual target task.Children attain near perfect scores on the same task.This difference is not due to 2D configuration, timing or attention.Adults improve when only one target is presented.Our results reflect disparity grouping operations that are immature in children. Abstract We report a series of experiments in which we assess depth discrimination performance in adults and children using a disparity‐balanced target configuration to avoid the effects of anticipatory vergence eye movements. In our first study we found that children outperformed adults by a substantial margin, and the adults were consistently near chance. This was surprising given that we initially tested naïve adults to provide a benchmark for the children’s data, and all observers met the criterion for stereoacuity. In subsequent experiments we recruited groups of inexperienced adult observers and assessed the role of a wide range of spatial and temporal factors in this apparent deficit. We found that the adult performance remained poor in spite of changes to the stimulus layout, exposure duration, and spatial scale. The only manipulations that improved performance were those that limited the binocular disparity to a single sign. We conclude that these data reflect a form of involuntary disparity pooling that makes it difficult for naïve observers to judge depth from disparity from multiple targets. The absence of this effect in children likely reflects the late maturation of global processes and depth cue integration.

Preference for motion and depth in 3D film

While heuristics have evolved over decades for the capture and display of conventional 2D film, it is not clear these always apply well to stereoscopic 3D (S3D) film. Further, while there has been considerable recent research on viewer comfort in S3D media, little attention has been paid to audience preferences for filming parameters in S3D. Here we evaluate viewers’ preferences for moving S3D film content in a theatre setting. Specifically we examine preferences for combinations of camera motion (speed and direction) and stereoscopic depth (IA). The amount of IA had no impact on clip preferences regardless of the direction or speed of camera movement. However, preferences were influenced by camera speed, but only in the in-depth condition where viewers preferred faster motion. Given that previous research shows that slower speeds are more comfortable for viewing S3D content, our results show that viewing preferences cannot be predicted simply from measures of comfort. Instead, it is clear that viewer response to S3D film is complex and that film parameters selected to enhance comfort may in some instances produce less appealing content.