Academic journal article Journal of Visual Impairment & Blindness

A New Look at Theory of Mind in Children with Ocular and Ocular-Plus Congenital Blindness

Academic journal article Journal of Visual Impairment & Blindness

A New Look at Theory of Mind in Children with Ocular and Ocular-Plus Congenital Blindness

Article excerpt

Theory of mind (ToM) refers to the understanding that mental states such as beliefs and desires govern human behavior. Previous studies have indicated a delay in the development of ToM in children with congenital blindness, despite their normal IQs (see, for example, Green, Pring, & Swettenham, 2004). Although the lack of vision and social experience is an obvious explanation for these delays--possibly in conjunction with additional impediments--there may also be alternative explanations more closely linked to the neuronal development of children with blindness. In fact, for many children, the cause for the blindness itself is linked to the optic neural pathways (hereafter referred to as "ocular-plus blindness"). These underlying neurological mechanisms may also influence the development of ToM abilities. Therefore, ToM delays might be more pronounced in children with ocular-plus blindness compared with children whose blindness does not involve the optic neural pathways (ocular blindness). The current study focused on ToM abilities of children with ocular-plus blindness compared with children with ocular blindness.

Blindness is defined by the World Health Organization as having visual acuity of less than 3/60 to no perception of light (World Health Organization, 2010). Blindness affects about .01% to .04% of all living births (Gilbert & Awan, 2003). Ocular and ocular-plus congenital blindness can be distinguished based on the cause of blindness located either before the optic tract (ocular blindness) or within the optic tract and further in the brain tissue (ocular-plus blindness). The optic tract is composed of a chain of four nerve cells. The first two neurons form the retina, and the third is the optic nerve. In the lateral geniculate nucleus, a part of the thalamus, the optic tract relays to the fourth neuron, projecting to the occipital lobe or visual cortex. The ocular-plus versus ocular partition in the visual function has been a subject of debate (Colenbrander, 2009; Dutton & Bax, 2010; Frebel, 2006). Although it was previously believed that the partition was made at the third neuron level, more recent studies show that information processing starts at the level of the retina (Roska, Molnar, & Werblin, 2006), and the retina activates brain plasticity (Morishita & Hensch, 2008; Sugiyama et al., 2008). Therefore, we define ocular-plus blindness as those diagnoses involving the retina and other parts of the optic tract and brain tissue, and ocular blindness as those diagnoses only involving all nonretinal parts of the eye globe.

ToM understanding is generally tested with false belief tasks. In these tasks, children are tested for their ability to reflect on a story character that has a false belief about a certain situation (for example, because the character is unaware that an object has been relocated). Typically developing children generally pass these tasks at around 6 years of age (Wellman, Cross, & Watson, 2001). Various studies have indicated delayed ToM development in children with congenital blindness, primarily based on standard false-belief tasks that were adapted for children with blindness (Green et al., 2004; McAlpine & Moore, 1995; Minter, Hobson, & Bishop, 1998; Peterson, Peterson, & Webb, 2000). These delays are usually ascribed to the absence of visual experiences in social and communicative interactions (see Sonksen& Dale, 2002, for a more multifaceted explanation). It can indeed be argued that the lack of vision prevents the development of important ToM precursors, such as sharing experiences based on joint visual attention and visual observations of subjective states (Bedny, Pascual-Leone, & Saxe, 2009; Minter et al., 1998). These explanations are very plausible. However, their plausibility might have caused researchers to overlook additional neuronal explanations for impaired ToM skills in children with congenital blindness.

The possibility of shared underlying neurological mechanisms for ToM delays and congenital blindness has received little scientific attention. …

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