How does this experiment prove a causal relation between coherence and good feelings?
This excerpt refers to an experiment described in Topolinski &amp; Strack (2009) and Topolinski &amp; Strack (2009), and is part of a series of experiments that used a variety of different methods to demonstrate the causal relation between affect and coherence, of which only 1 is described above, so even if it isn't convincing by itself, a lot of additional evidence would need to be questioned to thwart the conclusion.

This particular experiment uses a popular paradigm developed by Schwarz &amp; Clore (1983) (which in turn is based on a previous experiment by Zanna &amp; Cooper (1974); for reviews see Schwarz &amp; Clore (1988), Schwarz &amp; Clore (1996), Schwarz (2012), and Wikipedia), that has been used many times to demonstrate a causal relation between affective experience and intuition or metacognition.  The premise behind this experimental paradigm is that once an affective experience is attributed to a particular cause, it is no longer used as information for subsequent judgments.  This assumption has been demonstrated in many experiments, but contrast it with Payne et al (2005) and Allen et al (1989) who report that attempts to correct misattribution failed in their studies, suggesting that affective experience information can be reused in some circumstances.  Luckily, this latter possibility does not impact the experiment in question.

The authors of this experiment propose a detailed mechanism for how subjects make judgments of coherence: As the word triad is read, the processing fluency (cognitive ease, or the rate that the words are processed) causes an affective response (subtle smiling reaction), that subjects become aware of, and attribute to subsequent intuitive judgments (such as coherence).

This particular experiment tests the hypothesis by manipulating subjects to misattribute the affective response (to background music).  Thus, if affect does not inform coherence judgments, then misattributing it to another source should have no effect on results.  On the other hand, if affect does cause coherence judgments, then attributing affective response to another cause should eliminate it as a source of information for coherence judgments, resulting in poorer performance.  The control group listened to the same music, and was also directed to misattribute something to it, but it was fluency rather than affect.



The results of the experiment indeed demonstrated that once subjects reattribute positive affect to background music, they no longer use it for coherence judgments, and this results in a significant reduction of correct responses, leading to the conclusion that affect is an important indicator (cause) of coherence.