Participants in a memory study say vivid images helped them recall a list of objects. Cognitive theorist Farah Lin argues that distinctiveness, not vividness itself, explains the advantage: unusual images stand out from one another. The experimenters note that their vivid images were also the most unusual. The author concludes that participants' introspections name a noticeable feature, whereas Lin's account proposes a causal mechanism the current design cannot isolate. Which option correctly attributes the two kinds of claim?