We often refer to space when we talk about time. To support this, studies show that we tend to associate the past with the left and the future with the right, space. However, there is little research that compares the spatial mapping of individual time units within the same methodological framework. Here, we used the same line-bisection paradigm to study horizontal spatial biases in various individual time units (i.e., hours, days, and months). Fifty-four adults processed temporal words and indicated their location on a horizontal line representing a time interval via a mouse click. Each word corresponded to one of the three conditions: left, right, or central position on the line. Our results show a reaction-time facilitation effect for hour and day units in congruent conditions (e.g., left semantic bias + left position on the line). Also, processing hour units shifted the response coordinates in the direction of the presumed spatial bias. Finally, the congruent combination of visual and semantic biases led to a shift in manual responses in the corresponding direction for all time units. We conclude that while left-to-right mapping of time concepts is relatively universal, the horizontal mapping is stronger for hours as compared with days and months.

Right hemispheric damage (RHD) caused by strokes often induce attentional disorders such as hemispatial neglect. Most patients with neglect over time have a reduction in their ipsilesional spatial attentional bias. Despite this improvement in spatial bias, many patients remain disabled. The cause of this chronic disability is not fully known, but even in the absence of a directional spatial attentional bias, patients with RHD may have an impaired ability to accurately and precisely allocate their spatial attention. This inaccuracy and variable directional allocation of spatial attention may be revealed by repeated performance on a spatial attentional task, such as line bisection (LBT). Participants with strokes of their right versus left (LHD) hemisphere along with healthy controls (HC) performed 24 consecutive trials of 24 cm horizontal line bisections. A vector analysis of the magnitude and direction of deviations from midline, as well as their standard deviations (SD), were calculated. The results demonstrated no significant difference between the LHD, RHD and HC groups in overall spatial bias (mean bisection including magnitude and direction); however, the RHD group had a significantly larger variability of their spatial errors (SD), and made larger errors (from midline) than did the LHD and HC groups. There was a curvilinear relationship between the RHD participants’ performance variability and their severity of their inaccuracy. Therefore, when compared to HC and LHD, the RHD subjects’ performance on the LBT is more variable and inaccurate. (JINS, 2015, 21, 373–377)

Proposals that adaptation with left-shifting prisms induces neglect-like symptoms in normal individuals rely on a dissociation between the postadaptation performance of individuals trained with left- versus right-shifting prisms (e.g., Colent, Pisella, & Rossetti, 2000). A potential problem with this evidence is that normal young adults have an a priori leftward bias (e.g., Jewell & McCourt, 2000). In Experiment 1, we compared the line bisection performance of young adults to that of aged adults, who as a group may lack a leftward bias in line bisection. Participants trained with both left- and right-shifting prisms. Consistent with our hypothesis, while young adults demonstrated aftereffects for left, but not right prisms, aged adults demonstrated reliable aftereffects for both prisms. In Experiment 2, we recruited a larger sample of young adults, some of whom were right-biased at baseline. We observed an interaction between baseline bias and prism-shift, consistent with the results of Experiment 1: Left-biased individuals showed a reduced aftereffect when training with right-shifting prisms and right-biased individuals showed a reduced aftereffect when training with left-shifting prisms. These results suggest that previous failures to find generalizable aftereffects with right-shifting prisms may be driven by participants’ baseline biases rather than specific effects of the prism itself. (JINS, 2010, 16, 795–804.)

In the current study, we investigated whether standard assessment techniques of visuospatial neglect are sensitive to detecting dissociable subtypes. We administered a battery of tasks commonly used to detect the presence of visuospatial neglect to 120 patients with unilateral right hemisphere infarcts and, in most cases, performed a systematic analysis of their lesions to quantify and localize brain damage. Using a factor analysis, we discovered seven relatively independent constructs, three of which were specifically related to the presence of left hemispatial neglect: Left Attentional Processing, Line Bisection. and Word Reading. Impairments in two of these factors. Left Attentional Processing and Line Bisection, occurred together in most cases but also occurred independently in 38 cases. There were no cases in whom Word Reading was present without concomitant deficits in one or the other two factors. These three factors could not be distinguished neuroanatomically; that is, lesions were equally likely in the temporal/parietal cortex, dorsolateral frontal cortex, or in deep frontal structures. These data confirm the notion that hemispatial neglect is a complex and multifaceted disorder composed of cognitively independent processes. These processes, however, cannot be dissociated neuroanatomically based on currently available assessment techniques. (JINS, 1996, 2, 441–451.)

Healthy subjects demonstrate leftward bias on visual–spatial tasks. However, young controls may also be left-biased when drawing communicatively, depicting the subject of a sentence leftward on a page relative to the sentence object, that is, a spatial–syntactic, implicit task. A leftward visual–spatial bias may decrease with aging, as right-hemisphere, dorsal, visual–spatial activation may be reduced in elderly subjects performing these tasks. We compared horizontal and radial (near–far) visual spatial bias, and spatial–syntactic bias, in healthy young and aged participants. Both horizontal and radial visual–spatial bias were smaller in aged participants when explicitly, but not implicitly assessed. Mean implicit far bias was greater in aged subjects, although this varied by task. We observed less implicit, spatial–syntactic left bias in aged than young participants. These results may be consistent with relatively less dominance of right hemisphere, dorsal spatial systems with aging. (JINS, 2008, 14, 562–570.)

The spatial allocation of attention influences estimates of stimulus magnitude, including line length and the line bisection task has been used to assess the asymmetrical allocation of spatial attention. The purpose of this study is to learn if normal subjects' allocation of attention changes as a function of the trunk–head centered spatial position of the line stimuli. Normal subjects were asked to bisect lines placed in five different head–trunk centered special positions (central, right up–distal, left up–distal, right down–proximal, left down–proximal). When compared with the central condition, deviations in the right or left lateral conditions were only significant in the down–proximal conditions, such that the bisection bias significantly shifted direction to the left of the objective midline in left hemispace and to the right of the objective midline in right hemispace, suggesting that stimuli presented in lateral hemispace primarily activate the contralateral hemisphere's attentional systems. The finding that the lines presented in down–proximal lateral hemispace induce a greater spatial bias than lines in up–distal lateral space suggests that the portion of the brain's dorsal visual system, which processes stimuli in down–proximal space, influences the horizontal (right–left) spatial allocation of attention more than does the brain's ventral visual system. (JINS, 2006, 12, 532–537.)

Isosceles triangular backgrounds influence line bisection performance in normal control participants and patients with hemispatial neglect. When the triangles are oriented asymmetrically with the vertex in 1 visual field, and the base in the other, the perceived midpoint of horizontal lines within the triangle is shifted towards the base, and away from the vertex. The current study examines this illusion further by systematically varying the extent of the triangle presented. With only fragments of the triangle in the background of the line, the vertex is the critical component driving the illusory shift in perceived midpoint. Patients with neglect and controls are equally sensitive to the illusion. Similar geometric illusions that are also intact in neglect, along with these results, suggest that preattentive, implicit visual processing is preserved in neglect and drives these illusions.

Most patients with neglect demonstrate a crossover effect on line bisection. Crossover refers to a pattern of performance in which long lines (>10 cm) are bisected ipsilateral to brain injury and short lines (<2 cm) are bisected contralateral to brain injury. Crossover bisections on short lines are of interest because they are not predicted by contemporary theories concerning neglect. However, we propose that the effect depends on two independent factors that normally influence bisection performance but are merely exaggerated in neglect—a tendency to overestimate the length of short lines and underestimate long lines and a tendency to orient attention preferentially in one spatial direction. We predicted that both patients with unilateral left and right hemisphere injury would demonstrate crossover on line bisection and that they would overestimate short lines and underestimate long lines upon direct visual inspection. Further, the 2 groups were predicted to demonstrate crossover in opposite directions owing to different lesion-induced biases in attentional orientation. Testing 5 patients with right hemisphere injury and 7 patients with left hemisphere injury confirmed each prediction. Additionally, errors in length estimation were exaggerated among patients with right hemisphere injury, most of whom had neglect. It is concluded that while crossover is accentuated in cases of neglect, it is not a consequence of neglect per se. As such, crossover bisections are not at odds with contemporary neglect theory. (JINS, 2002, 8, 107–114.)

Various factors influence the degree of leftward error (pseudoneglect) that typifies the performance of normal individuals in line bisection tasks. This experiment reveals that the eye through which stimuli are viewed also exerts a modulating influence on spatial attention, as indexed by significant alterations in the magnitude of pseudoneglect. Using a forced-choice tachistoscopic line bisection protocol, 24 participants (12 male; 12 female) bisected horizontally oriented lines (22.6° w × 0.39° h) presented to central vision in 3 conditions: left uniocular viewing (L), right uniocular viewing (R), and binocular viewing (B). Perceived line midpoint, a measure of bisection accuracy, deviated significantly leftward of veridical ( p < .05) in all viewing conditions, confirming a tonic asymmetry of visuospatial attention in normal young observers. In addition, a significant influence of viewing condition was found (p < .05) where pseudoneglect was greatest in the L condition, followed by the B and R conditions, respectively. Analysis of the slopes of the psychometric functions revealed significantly greater bisection precision in the binocular versus uniocular viewing conditions (p < .05). The results are interpreted to suggest that phasic effects on spatial attention can be produced by uniocular viewing via asymmetric retinotectal projections. The results are consistent with activation–orientation theories of attentional asymmetry. (JINS, 2001, 7, 391–395.)

Neglect in the horizontal and vertical axes of space has been observed after acute right anterior choroidal artery (AChA) lesions. How spatial processing is affected in the radial axis during the acute period following infarction in this region is unknown. We report the case of a 69-year-old man with acute left hemineglect and deficits in 3-dimensional spatial processing following right AChA infarction. His line bisections in 4 spatial conditions, oriented in the 3 primary axes of space, were compared with 6 control participants. The patient's bisections were different from true center and from control performance in all axes. His bisections were to the right, below, and distal to the arithmetic midpoint. This patient's bisection errors show a 3-dimensional neglect pattern following right AChA infarction, supporting the view that processing of all 3 spatial dimensions may be simultaneously disturbed following unilateral right hemisphere lesions. (JINS, 1999, 5, 567–571.)