Evidence-Based Practice

In a study by Dada et. al (2013), 30 participants with mild intellectual disabilities "were required to identify target PCS out of 16 PCS from a themed bed-making communication overlay" (p. 363). The results revealed that the symbols were iconic, as the participants were able to select half of the symbols with 75% accuracy (Dada et. al, 2013).  

A further word on the importance of iconicity. 

It is important to note, that symbol selection must be modified until a child or young person arrives at "representational insight" or "when children recognize some kind of relationship between the picture and referent (Stephenson & Linfoot, (1996) as cited in Dada et. al 2013). 

This type of insight is dependent on the iconicity of the symbol (Dada et al. 2013). They further explain that "iconicity exists on a continuum, with transparency at one end and opaqueness at the other (Lloyd & Fuller (1990) as cited in Dada et. al. 2013). Moreover, "a symbol is considered transparent when its visual aspects are highly suggestive of its referent, and therefore the meaning can be easily determined by the naive viewers once the referent is known" (Blischak et al., (1997) as cited in Dada et. al 2013). 

So in other words, clinicians must be careful to provide a wide selection of PSC (e.g., Black & Whiteline drawings, Tobii Dynavox InContext, Boardmaker-Classic, etc) for the child or young person to be able to discriminate the symbols that make the most sense to their communication needs.