Participants liked disliked individuals less, had less knowledge about them, and spent less time with them compared to liked individuals.

Exp. 3 Results: Liking, Knowledge, and Time Together (Alves et al., 2016)

Similarity was assessed using a Euclidian distance measure. They found that there was a significantly smaller mean distance between the liked individuals than there was between the disliked individuals. That is, people perceived the liked individuals to be more similar to each other. 

Exp. 3 Results: Similarities (Alves et al., 2016)

Participants were faster at making comparisons for two liked individuals than they were  for 2 disliked individuals; they suggest that people engaged in more effortful processing strategies when making judgements about negative stimuli (e.g. there could be a processing difference). 

Exp. 3 Results: Response Times For Judgments (Alves et al., 2016)

Participants listed 4 people that they liked and 4 that they disliked. Similarity among the liked and disliked others was assessed using pairwise ratings on a 1-9 scale to questions such as "How similar are Liked Person 1 and Liked Person 2 to each other regarding their personalities?”. Participants also indicated how much they liked, knew, and how much time they spent with each person.

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We tend to have more knowledge about people we like compared to those that we dislike. Intuitively, one would think if we have more knowledge about various individuals we would see them as being more unique. However, research suggest this is not always true. This series of studies investigated if people tend to view liked others as more similar to themselves and others when compared to disliked others despite having more knowledge about them. 

My Friends Are All Alike: Liking and Similarity  

Alves, H., Koch, A., & Unkelbach, C. (2016). My friends are all alike—the relation between liking and perceived similarity in person perception. Journal of Experimental Social Psychology, 62, 103-117.

My Friends Are All Alike

Asked participants to provide the names of 4 people they know well and liked as well as 4 people they knew, but did not like. They had to create a similarity map for these 8 individuals.  

Experiment 1; My Friends Are All Alike

Participants were randomly assigned to a liked or disliked condition; they were instructed to make a similarity map for either 4 people they liked or disliked. Participants also indicated how much they liked, knew, and the amount of time typically spent with each person. 
This was done to see if liked targets only appeared more similar in experiment 1 solely because they were also in the presence of disliked individuals.

Experiment 2; All My Friends Are Alike

Experiment 3; All My Friends Are Alike

Participants were instructed to think of as many traits as they could for each of the 4 liked and disliked individuals; additionally, they were asked comparison questions such as "How similar are Disliked Person 1 and Disliked Person 2 to each other in terms of __?" Similarity among the individuals was then assessed using the pairwise functions. Participants also were instructed to indicate how much they liked, knew, and how much time they spent with each person. 

Experiment 4; My Friends Are All Alike

Investigates how similar we perceive liked people and disliked when we don't know them very well (e.g. public figures and celebrities). Participants provided the names of 4 liked and 4 disliked celebrities. They were asked questions such as "How similar are Disliked Celebrity 1 and Disliked Celebrity 2 to each other in terms of __?" They also reported how much they knew and liked each individual. 

Experiment 5; My Friends Are All Alike

This investigated the impacts of ratings of larger groups of liked and disliked people would have on the similarity levels. They predicted that by asking participants to think of many celebrities, they would be more likely to pick a diverse set of people; thus, influencing how similar they were all to each other. They asked participants to think of 12 celebrities they liked and disliked; however, only 4 of each were randomly selected for the participants to make comparison ratings about (e.g. Celebrity 1 is more sociable than Celebrity 2).  

Experiment 6; My Friends Are All Alike

This experiment asked people to indicate 2 people that they know personally (did not have to be exclusively liked or disliked). They were then asked to identify either as many positive or negative traits as they could about each one. Afterwards, they were asked how similar they were to one another.  

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