Following acquired brain injury, it is common for people to encounter difficulties with walking (Carvalho-Pinto & Faria,
2016). In many cases, these difficulties are due to problems generating physical movements or maintaining balance (Langhorne, Coupar, & Pollock,
2009). Other difficulties may have a perceptual origin. There are two common conditions in which the awareness of objects on one side of space is impaired:
homonymous hemianopia (HH) and
unilateral visual neglect (UVN). HH, following damage to the optic radiations or primary visual cortex (Hutchins & Corbett,
1997), is the loss of vision in one hemifield, to the left or right of fixation (Millodot,
2004). Detailed reports in the literature of people with HH colliding with objects and having other difficulties walking (M. Warren,
2009) are sparse, but the problem is broadly recognized (Chokron, Perez, & Peyrin,
2016) and solutions have been proposed (e.g., Bowers, Keeney, & Peli,
2008; Pundlik, Tomasi, & Luo,
2015). UVN, which can result from damage to a number of sites (Vallar,
1998; Verdon, Schwartz, Lovblad, Hauert, & Vuilleumier,
2010) but most commonly parietal damage, is not a loss of vision but a loss of awareness of one side of space (Vallar,
1998)—an attentional or representational impairment (Heilman & Valenstein,
2011). People with UVN (many of whom will also have HH) are reported to bump into obstacles and take curved or abnormal trajectories (e.g., Huitema et al.,
2006; Robertson, Tegnér, Goodrich, & Wilson,
1994; Tromp, Dinkla, & Mulder,
1995; Turton et al.,
2009). Collisions with obstacles have also been reported in people with UVN (Aravind, Darekar, Fung, & Lamontagne,
2015; Turton et al.,
2009).