In the last post, I discussed the similarities and differences between language and other types of information. From the first person perspective, spoken language is just another type of auditory event. The main distinction between the word "dog" and the sound of a dog barking is that the auditory event of barking is about the thing that caused the sound - a barking dog - while the auditory event of the word "dog" is not about the thing that caused the sound - a human speaker. The word "dog" is (usually) about an animal that is related to the auditory event by convention. Thus, the sound of a barking dog conveys auditory information and the sound of the word "dog" conveys linguistic information.
In this post I want to lay out classes of tasks in which linguistic information is useful. As a starting point, I will identify situations where language appears to fill a gap, although at this point these are no more than general descriptions. In any specific task analyses that might eventually follow, the basic strategy will be to begin by asking what perceptual resources exist to carry out the task. If perceptual resources are unable to explain task performance and if linguistic resources are available, then these will be considered for their potential contribution. It might be helpful to think of linguistic and perceptual information as occupying different niches in a task space. Perceptual information helps me to walk and catch a fly ball and linguistic information helps me do the types of things described below.