I'm reading Thinking, Fast and Slow by Daniel Kahneman and I came across the following text:
The Remote Association Test has more to tell us about the link between cognitive ease and positive effect. Briefly consider the two triads of words:
$$\text{sleep mail switch}\\\text{ salt deep foam}$$ You could not know it of course, but measurements of electrical activity in the muscles of your face would probably have shown a slight smile when you read the second trial, which is coherent (sea is the solution). This smiling reaction to coherence appears in subjects who are told nothing about common associates; they are merely shown a vertically arranged triad of words and instructed to press the space bar after they have read it. The impression of cognitive ease that comes with the presentation of a coherent triad appears to be mildly pleasurable in itself. The evidence that we have about good feelings, cognitive ease, and the intuition of coherence is, as scientists say, correlational but not necessarily causal. Cognitive ease and smiling occur together, but do the good feelings actually lead to intuitions of coherence? Yes, they do. The proof comes from a clever experimental approach that has become increasingly popular. Some participants were given a cover story that provided an alternative interpretation for their good feeling: they were told about music played in their earphones that "previous research showed that this music influences the emotional reaction of its individuals". This story completely eliminates the intuition of coherence. The finding shows that the brief emotional response that follows the presentation of a triad of words (pleasant if the triad is coherent, unpleasant otherwise) is actually the basis of judgments of coherence. There is nothing here that system 1 cannot do. Emotional changes are now expected, and because they are unsurprising they are not linked causally to the words.
(Kahneman refers to the automatic and intuitive way of thinking as system 1)
My Question: Why does the adding of the cover story in this experiment show that good feelings lead to intuitions of coherence (that there is a causal relation)? I find this conclusion rather strange. I'm probably mistaken but it seems to me that Kahneman is saying: the fact that there was no intuition of coherence when these participants were expecting to respond emotionally to music, shows that there is a causal relation between the good feelings and the intuition of coherence. Why would this make sense?