For simplicity, we model the stimulus as a collection of unigrams.
consider the following conditional entropy: where b i is a block of N − 1 tokens in a response r, j is an arbitrary token following b i , and s k is an arbitrary token in the corresponding stimulus s for r. Note that for each b i , we consider every token in the corresponding s. a (stimulus, response) pair with m and n tokens respectively generates m * (n− N + 1) observations of (b i , j, s k ) tuples.