Vertical–horizontal illusion

The vertical–horizontal illusion is the tendency for observers to overestimate the length of a vertical line relative to a horizontal line of the same length.^[1] This involves a bisecting component that causes the bisecting line to appear longer than the line that is bisected. People often overestimate or underestimate the length of the bisecting line relative to the bisected line of the same length.^[2] This even happens if people are aware that the lines are of the same length.

Cross-cultural differences in susceptibility to the vertical–horizontal illusion have been noted. People from Western cultures and people living in urban landscapes show more susceptibility than those living in eastern or open landscapes.^[3]

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I'm going to show you some images and you're going to have to make some quick decisions. Is line a or line b longer? Is the horizontal or vertical line longer? Is the top or bottom line longer? Keep looking... In all of these images they're actually the same length. You may have seen these before— but you're more susceptible to be tricked by these illusions — or not — depending on where you live. Two studies 50 years apart showed that non-Western people were less likely to be tricked by the Müller-Lyer or Parallelogram illusion than Europeans and Americans. And they were more susceptible to the horizontal-vertical illusion. The researchers suggest that the physical environment you live in shapes your susceptibility to certain illusions. If you live somewhere with lots of open plains, you're more likely to be tricked by the horizontal-vertical illusion because you're not as familiar with seeing vertical and horizontal objects at Urban dwellers are moderately susceptible and people who live in restricted environments, like a dense forest, or a big city, aren't as easily tricked. There's plenty of straight line things around for us to develop a frame of reference, like tall buildings or trees. It's mind blowing to think that the visual experiences you've had in life affects your perception of objects. Our basic biological process of seeing something like these lines is the same, but we've all developed different habits of how we perceive them. And experiments have manipulated the process of how we see objects. In cats. In cats wearing an eyepatch. In one study, a kitten reared with an eyepatch over one eye for 6 months had impaired depth perception. The cat still had two normal eyes, but a greater area of the visual cortex was devoted to analysing information from the unpatched eye than the patched eye. Another study went a whisker further. Researchers raised two groups of kittens in the dark, and when they were exposed to light they wore goggles that restricted them to see in either horizontal lines or vertical lines. When the goggles were removed, the cats were blind to lines running the other way. The horizontal cats could sit on a chair, but would bump into the chair’s legs. The vertical cats could avoid the chair legs, but missed when they tried to jump on the chair. The researchers discovered the visual cortex contains nerve cells called “feature detectors” – they respond only when we’re shown a line with a certain orientation, like horizontal or vertical. The cat’s brains dedicated these nerve cells to one orientation and neglected the other. Just like the influence of where we live, the early visual experiences of the cats shaped how they perceived the physical world. So, were you tricked by these illusions? Let me know down if the comments if you were and what kind of environment you're from. And remember that in those studies I mentioned they're observed as an effect over lots of people. So it doesn't necessarily mean that if you're from a city you're going to be more or less tricked by an illusion. But, if enough people comment maybe we observe an effect from the people that watch this video. So let me know.

Types of vertical–horizontal illusions

There are several different configurations of the vertical–horizontal illusion. The three configurations which seem to produce the highest illusion magnitude are the L configuration, the plus (+) configuration, and the inverted-T configuration. Of these three, the inverted-T configuration produces the highest illusion magnitude. When the bisecting line of the T illusion is configured horizontally, the illusion magnitude is lowered. However, when the bisecting line of the T illusion is configured vertically, the illusion magnitude is higher.^[4]

Development

A gradual decrease in error of vertical–horizontal illusions occur as participants age increases from eight to fourteen years.^[5] Gough and Meschieri attribute this decrease in error to the child's improved ability to detect and de-center their attention in a visual display, i.e. position their body differently to gain other perspectives.^[6] Children who showed greater personal independence, verbal articulation, and visual scanning ability were more effective and resourceful in their ability to gauge vertical–horizontal illusions.^[6]

Cross-cultural differences

Cross-cultural differences in susceptibility to the vertical–horizontal illusion have been noted in several studies. People living in developed urban cities show greater susceptibility than people living in rural areas.^[7] An explanation could be that those in rural areas are more accustomed to living in round houses on flat plains, or scrubland. Rural inhabitants have more exposure to distance and living on plains than people living in highly developed, commercialized cultures. However, differences in the strength of the vertical-horizontal illusion or the related Müller-Lyer illusion for these groups are inconsistent at best.^[8]

Hemispheric neglect

Participants with hemispatial neglect had increased difficulty perceiving the equality of the lines on the vertical–horizontal illusion, in comparison with those in the control group. Montalembert's study, among others, gives claim to the notion that we perceive these types of illusions utilizing the left hemisphere of our brain.^[9]

Gender differences

Gender differences have been found with regards to vertical–horizontal illusions. Rasmjou's 1998 study found men to outperform women in perceiving the vertical–horizontal illusion. The results of this variation could be from hemispheric asymmetries, and/or biological differences between men's and women's brains.^[9] Although women were found to have a higher illusion magnitude on vertical–horizontal illusion tasks, this does not mean men are better judges of distance than women, as there has been minimal research on this topic. Additional research is needed to draw a significant relationship between illusion magnitude and real-world tasks. These differences could also be due to social learning differences between men and women.

Functional applications

Functional applications of vertical–horizontal illusion exist. Elliot et al. studied the effects of the horizontal and vertical illusion, and how the perceived illusion can influence visuo-motor coordination, i.e. motor activity dependent on sight.^[10] The study specifically focused on how the perceived height of a step, manipulated by the vertical and horizontal illusion, influenced stepping strategy as shown in toe elevation during step clearance. Their results showed an increased toe elevation in conditions where an illusion was perceived, leading them to conclude that there was a correlation between visual illusion and visuo-motor coordination. This can be implemented in the real world by developing better safety strategies in places such as nursing homes.

References

^ Robinson, J.O. (1998). The psychology of visual illusion. Courier Dover Publications. p. 96. ISBN 978-0-486-40449-3.
^ de Montalembert, M., & Mamassian, P. (2010). The Vertical–Horizontal Illusion in Hemi-Spatial Neglect. Neuropsychologia, 48(11), 3245-3251. doi:10.1016/j.neuropsychologia.2010.07.002.
^ Shiraev, E., & Levy, D. (2007). Cross-Cultural Psychology, Third Edition. Pearson Education, Inc., page 110
^ Wolfe, U., Maloney, L.T., & Tam, M. (2005). Distortions of perceived length in the frontoparallel plane: Tests of perspective theories. Perception & Psychophysics, 67(6), 967-979.
^ Winch, W.H. (1907). The Vertical-Horizontal Illusion in School Children. British Journal of Psychology II, 220-225.
^ ^a ^b Gough, Harrison & Meschieri, Luigi (1971). Cross-Cultural Study of Age-Related Differences in Perceptual Acuity. Journal of Consulting and Clinical Psychology, 37(1), 135-140.
^ Mast, F.W., & Oman, C.M. (2004). Top-Down Processing and Visual Reorientation Illusions in a Virtual Reality Environment. Swiss Journal of Psychology, 63(3), 143-149. doi:10.1024/1421-0185.63.3.143.
^ Robinson, J.O. (1972). The Psychology of Visual Illusion. Oxford, England: Hutchinson University Library.
^ ^a ^b Rasmjou, S., Hausmann, M., & Güntürkün, O. (1999). Hemispheric Dominance and Gender in the Perception of an Illusion. Neuropsychologia, 37(9), 1041-1047. doi:10.1016/S0028-3932(98)00154-7.
^ Elliott, D.B., Vale, A., Whitaker, D., & Buckley J.G. (2009). Does My Step Look Big In This? A Visual Illusion Leads To Safer Stepping Behaviour. PLoS ONE 4(2): e4577. doi:10.1371/journal.pone.0004577.

v t e Optical illusions (list)
Illusions	Afterimage Ambigram Ambiguous image Ames room Autostereogram Barberpole Bezold Café wall Checker shadow Chubb Cornsweet Delboeuf Ebbinghaus Ehrenstein Flash lag Fraser spiral Gravity hill Grid Hering Impossible trident Irradiation Jastrow Lilac chaser Mach bands McCollough Müller-Lyer Necker cube Oppel-Kundt Orbison Penrose stairs Penrose triangle Peripheral drift Poggendorff Ponzo Rubin vase Sander Schroeder stairs Shepard tables Spinning dancer Ternus Vertical–horizontal White's Wundt Zöllner
Popular culture	Op art Trompe-l'œil Spectropia (1864 book) Ascending and Descending (1960 drawing) Waterfall (1961 drawing) The dress (2015 photograph)
Related	Accidental viewpoint Auditory illusions Tactile illusions Temporal illusion

This page was last edited on 14 September 2021, at 13:47

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