Participants in a voter preference study favored the presidential candidate whose face blended some of their own facial features with those of the candidate. This best illustrates the impact of
a. deindividuation
b. chameleon effect.
c. social facilitation
d. the mere exposure effect.

The question that we have here illustrates the impact of the mere exposure effect. The answer to this question is option D.

The mere exposure effect can be described as a type of bias that people may display. It explains the tendency that human beings may have towards things.

A person may begin to prefer something just because they share some similarities with that thing.

In this case, the participants in the voter study preferred the presidential candidate for having similar facial features as they had.

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Participants in a voter preference study favored the presidential candidate whose face blended some of their own facial features with those of the candidate. This best illustrates the impact of d. the mere exposure effect.  

Explanation:

Psychology defines mere-exposure effect as a phenomenon by which people tend to develop a particularity for the things merely as they are familiar with them. This effect is also known as familiarity principle.

Mere-exposure to a particular event may increase out the liking towards it. The effect states that if we are most exposed to a person or a thing our liking towards it will increase. Mere-exposure effect was found by the psychologist Robert Zajonc.

answer; john stuart mill's principle of utility is your answer; /// good luck