Two stages have been suggested in children's understanding of the mind between ages 4 and 8. The first stage is signalled by success on false belief tasks around age 4 and is thought to indicate an understanding of the mind as ‘representational’. The second stage is signalled by success on ambiguity tasks around age 6–8 and is thought to indicate a new understanding that people ‘interpret’ or ‘process’ perceptual information. The study reported here was carried out with 108 subjects aged 3–6 to determine whether children begin to understand that ambiguous visual cues are an insufficient source of knowledge around age 6 as previous research suggests (e.g. Taylor, 1988), or whether this development occurs around age 4 when they begin to understand related tasks such as false belief. Two differently coloured (unambiguous) and two same coloured (ambiguous) stuffed animals were introduced to a subject and another character. The animals from one pair were then secretly placed in two separate boxes which had a small hole in the centre enabling a viewer to see each animal's colour but not the shape. Almost no 3‐year‐olds, but about half the 4‐year‐olds and most 5‐ and 6‐year‐olds, recognized that the other could identify the unambiguous pair, but not the ambiguous pair. It is argued that an understanding of ambiguity develops around age 4 because it requires an understanding that beliefs may be false, and that there is one stage (at least with respect to the