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Gabriel Nevarez

Publications and source records attributed to Gabriel Nevarez.

2 recordsLinked to original sources

Induced visual fading of complex images.

Visual stimuli fade from awareness under retinal stabilization or careful fixation, a phenomenon documented by Troxler more than 200 years ago. Research on visual fading during normal visual fixation typically has been restricted to discrete, simple, low-contrast shapes presented peripherally against a uniform or textured background. In four experiments, we document a striking new visual fading effect in which entire photographs of scenes fade to a uniform luminance and hue during normal visual fixation. Critically, this "scene fading" can be induced almost instantaneously by some types of visual transients but not by others. These induced fading effects are sufficiently robust that they can be experienced by most observers in a single trial. Taken as a whole, the effects are inconsistent with simple contrast adaptation, gradual Troxler fading, or transient-induced fading. They are, however, consistent with the idea that small contrast decrements can induce fading of entire scenes. The methods provide a robust tool for the exploration of visual fading, and the results could have important implications for the role of filling-in and neural adaptation in our visual awareness of natural scenes and other complex stimuli.

Color↗

Visual sensing IS seeing: why "mindsight," in hindsight, is blind.

Faced with the surprising failure to notice large changes to visual scenes (change blindness), many researchers have sought evidence for alternative, nonattentional routes to change detection. A recent article in Psychological Science (Rensink, 2004) proposed a new, nonsensory "mindsight" mechanism to explain the finding that some subjects on some trials reported sensing the presence of a recurring change before they could explicitly identify it and without having a localizable visual experience of change. This mechanism would constitute a previously unknown mode of seeing that, as Rensink suggested, might be akin to a sixth sense. Its existence would have radical implications for the mechanisms underlying conscious visual experience. Provocative claims merit rigorous scrutiny. We rebut the existence of a mindsight mechanism by supporting a more mundane explanation: Some subjects take time to verify their initial conscious detection of changes.

Humans↗