Inside The Consumer Mind: Brain Scans Reveal Choice Mechanism

shows that decision making is simplified when a consumer considers a third, less attractive option

The less appealing sweater plays the role of a "decoy" that makes the other sweater appear more pleasing than before.

the presence of a relatively unattractive option improves the choice share of the most similar, better item."

"Trade-off Aversion as an Explanation for the Attraction Effect:

Volunteers had their brains scanned while they made choices between several sets of equally appealing options as well as choice sets that included a third, somewhat less attractive option

presence of the extra, "just okay" possibility systematically increased preference for the better options

making a choice between only two, equally preferred options; subjects tended to display irritation

The presence of the third option made the choice process easier and relatively more pleasurable.