Is the Vertical-Horizontal Illusion a Byproduct of the Environmental Vertical Illusion?

The vertical-horizontal illusion is the overestimation of a vertical line compared to a horizontal line of the same length. Jackson and Cormack (2007) proposed that the vertical-horizontal illusion might be a byproduct of the mechanisms that generate the environmental vertical illusion, which is the tendency to overestimate vertical distances (i.e.

Evolved navigation illusion provides universal human perception measure.

The ability to replicate an experiment across any scientific discipline rests on the assumption that different experimenters are capable of perceiving the same methods and outcomes. However, the large individual differences in experimenters' visual perception undermine this tenet of the scientific process. Further, common devices for measuring similarity in perceptual capacity do not replicate across human groups.

Visual field dependence as a navigational strategy.

Visual perception is an important component of environmental navigation. Previous research has revealed large individual differences in navigational strategies (i.e.

Animacy, perceptual load, and inattentional blindness.

Inattentional blindness is the failure to notice unexpected objects in a visual scene while engaging in an attention-demanding task. We examined the effects of animacy and perceptual load on inattentional blindness. Participants searched for a category exemplar under low or high perceptual load.

Evolutionary relevance facilitates visual information processing.

Visual search of the environment is a fundamental human behavior that perceptual load affects powerfully. Previously investigated means for overcoming the inhibitions of high perceptual load, however, generalize poorly to real-world human behavior. We hypothesized that humans would process evolutionarily relevant stimuli more efficiently than evolutionarily novel stimuli, and evolutionary relevance would mitigate the repercussions of high perceptual load during visual search.

Context is quick, knowledge is slow: rapid time-course of contextual modulations in the horizontal-vertical illusion.

One of the oldest visual illusions consists of observers' tendency to estimate vertical lines as longer than equal horizontal lines. This Horizontal-Vertical Illusion has been studied widely; however, most studies may not generalize to natural contexts because they have not addressed the low-level processes that occur rapidly and in response to context-free lines vs the possibility for high-level processes that arise over time in response to context. These issues were investigated via a novel design: rapid time-sequencing embedded within the context of natural images.

Evolved navigation theory and the plateau illusion.

Most people anecdotally feel that the distance extending toward a cliff or slope appears shorter than the same distance extending away from it. This odd impression persists, despite the distance being equal across both conditions and humans encountering such a scenario daily in the navigation of stairs, slopes, curbs, and vertical surfaces protected by handrails. We tested three sets of competing predictions about this previously uninvestigated phenomenon.

Learning and exposure affect environmental perception less than evolutionary navigation costs.

Most behaviors are conditional upon successful navigation of the environment, which depends upon distance perception learned over repeated trials. Unfortunately, we understand little about how learning affects distance perception-especially in the most common human navigational scenario, that of adult navigation in familiar environments. Further, dominant theories predict mutually exclusive effects of learning on distance perception, especially when the risks or costs of navigation differ.

Preference for the nearer of otherwise equivalent navigational goals quantifies behavioral motivation and natural selection.

Navigation and environmental perception precede most actions in mobile organisms. Navigation is based upon the fundamental assumption of a ubiquitous Preference for the Nearest of otherwise equivalent navigational goals (PfN). However, the magnitude and triggers for PfN are unknown and there is no clear evidence that PfN exists.

Evolved navigation theory and horizontal visual illusions.

Environmental perception is prerequisite to most vertebrate behavior and its modern investigation initiated the founding of experimental psychology. Navigation costs may affect environmental perception, such as overestimating distances while encumbered (Solomon, 1949). However, little is known about how this occurs in real-world navigation or how it may have evolved.

Reducing the presence of navigation risk eliminates strong environmental illusions.

Many researchers have assumed that navigational costs, as opposed to the visual stimuli per se, produce several large-magnitude distance illusions-in spite of the absence of experimental data. We used virtual reality to remove the presence of realistic falling costs, while leaving the visual information otherwise intact. This resulted in removal of the distance illusions proposed to have evolved in response to falling costs.

Individual differences in distance perception.

Distance perception is among the most pervasive mental phenomena and the oldest research topics in behavioural science. However, we do not understand well the most pervasive finding of distance perception research, that of large individual differences. There are large individual differences in acrophobia (fear of heights), which we commonly assume consists of an abnormal fear of stimuli perceived normally.

Evolved navigation theory and the descent illusion.

Researchers often assume that height perception results from all of the same mechanisms as does other distance perception. Evolved navigation theory (ENT) proposes that natural selection has differentiated some psychological processes, including height perception, in response to the navigational outcome of falling. We tested predictions from three theories in two experiments.