Basis of the horizontal-vertical illusion.

Avery, Gayle C.; Day, R. H.

doi:10.1037/h0027737

Cited by 131 publications

(128 citation statements)

References 14 publications

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“…a relative overestimation of vertical extents relative to horizontal ones-as has often been demonstrated with an L figure (e.g., Avery & Day, 1969; but see Chapanis & Mankin, 1967, for exceptions). Finger and Spelt (1947) were among the first to note that Titchener's ⊥ incorporates at least two illusioninducing factors: the orientation of the lines and the bisection of the horizontal line by the vertical one.…”

mentioning

confidence: 63%

Titchener’s ⊥ dissected

Landwehr

2015

Atten Percept Psychophys

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In three experiments, two independent samples of 12 observers each visually inspected modified versions of Titchener's ⊥ from which the T-junctions had been deleted. For Experiment 1, the ⊥'s two lines had been replaced by dashed lines not meeting in a common point; for Experiment 2, the ⊥ had been reduced to five dots, representing the original lines' end-and midpoints; and for Experiment 3 (in which the second sample of observers served), the ⊥ had been dissected into two separate lines, differently spaced from each other. Observers haptically indicated the lengths of the two orthogonal lines of the modified ⊥s and verbally judged their relative lengths or the distances between the corresponding dots. The common perceptual illusions persisted in Experiments 1 and 2, but were markedly weakened in Experiment 3. Implications for a neurophysiological account of the illusions in terms of bottom-up, long-range interactions between orientation-sensitive mechanisms versus top-down activation of a figural schema are spelled out.

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confidence: 63%

Titchener’s ⊥ dissected

Landwehr

2015

Atten Percept Psychophys

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“…It is known that asymmetries exist in judgments of length in the vertical and horizontal dimensions. This asymmetry is clearly demonstrated by the horizontal vertical illusion (Avery & Day, 1969), in which the length of the vertical segment of an inverted BT^is overestimated relative to the horizontal segment. This overestimation is thought to arise from a vertical bias (in which the length of vertical lines is overestimated) and a bisection bias (in which bisected lines appear shorter) (Josev, Forte & Nicholls, 2011).…”

Section: Discussionmentioning

confidence: 99%

An investigation of the mechanisms underlying the effects of viewing distance and stimulus length on attentional asymmetries during line bisection

Nicholls

Beckman

Churches

2016

Atten Percept Psychophys

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Clinical neglect patients overattend to stimuli on their right, whereas the general population overattend to the left (pseudoneglect). Both phenomena are affected by viewing distance, whereby the attentional biases are attenuated as the stimulus moves from near to far space. Both are also affected by stimulus length and reduce in strength, or even reverse (the crossover effect), as length decreases. To gain an insight into the cognitive/neural mechanisms that underlie the effects of viewing distance and stimulus length, in two experiments we examined the interaction between the variables. In Experiment 1 we asked university students (n = 20) to perform a horizontal landmark bisection task with lines presented at varying lengths (1.2°, 6.3°, and 18.4°of viewing angle) and distances (450 and 1,350 mm). A crossover effect and pseudoneglect were observed for the short and the long lines, respectively. An effect of viewing distance was only observed for long lines. Experiment 2 was the same, except that the lines were rotated to form vertical lines. No crossover effect was observed for the short lines, but an upward bias was observed for the long lines. Once again, an effect of viewing distance was only apparent for the long lines. These results demonstrate that the crossover effect is not a general property of short lines and is specific to the horizontal dimension. Models of crossover therefore need to incorporate processes related to left-right asymmetries. The results also demonstrate that viewing distance only affects long lines, and that this happens irrespective of orientation. A model of viewing distance is discussed that incorporates a right hemisphere mechanism specialized for an interaction between the ventral and dorsal streams.

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“…Previous research suggests that the presence of a horizontal-vertical illusion (Avery and Day 1969) superimposed on to the front face (riser) of a single wooden block led to a perceived increase in height of the block and a resulting increase in toe elevation when participants (mean age ± 1 SD: 28.2 ± 8 years) walked up to and onto the block (Elliott et al 2009). The simplest version of the horizontal-vertical illusion is a large letter T with limbs of equal size, where the vertical limb appears noticeably longer than the horizontal one ( Figure 1).…”

Section: Introductionmentioning

confidence: 99%

The addition of stripes (a version of the ‘horizontal-vertical illusion’) increases foot clearance when crossing low-height obstacles

et al. 2015

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Citation: Foster RJ, Buckley JG, Whitaker D and Elliott DB (2016) The addition of stripes (a version of the 'horizontal-vertical illusion') increases foot clearance when crossing low-height obstacles, Ergonomics. 59(7): 884-889. The authors thank Georgia Halstead for her help during data collection. AbstractTrips over obstacles are one of the main causes of falling in older adults, with vision playing an important role in successful obstacle negotiation. We determined whether a horizontal-vertical illusion, superimposed onto low-height obstacles to create a perceived increase in obstacle height, increased foot clearances during obstacle negotiation thus reducing the likelihood of tripping. Eleven adults (mean±1SD: age 27.3±5.1 years) negotiated obstacles of varying heights (3, 5, 7 cm) with four different appearance conditions; two were obstacles with a horizontal-vertical illusion (vertical stripes of different thickness) superimposed on the front, one was a plain obstacle and the fourth a plain obstacle with a horizontal black line painted on the top-edge. Foot clearance parameters were compared across conditions. Both illusions led to a significant increase in foot clearance when crossing the obstacle, compared to the plain condition, irrespective of obstacle height. Superimposing a horizontal-vertical illusion onto low-height obstacles can increase foot clearance and its use on the floor-section of a double-glazing door frame for example, may reduce the incidence of tripping in the home. Practitioner summaryLow-height obstacles such as the floor-section of a double-glazing door frame are potential tripping hazards. In a gait lab-based study we found that a horizontalvertical illusion superimposed onto low-height obstacles led to significantly higher foot clearances; indicating their potential as a useful safety measure.

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Basis of the horizontal-vertical illusion.

Cited by 131 publications

References 14 publications

Titchener’s ⊥ dissected

Titchener’s ⊥ dissected

An investigation of the mechanisms underlying the effects of viewing distance and stimulus length on attentional asymmetries during line bisection

The addition of stripes (a version of the ‘horizontal-vertical illusion’) increases foot clearance when crossing low-height obstacles

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