Notes on Superiority Bias

This more commonly goes by the name of "Lake Wobegon Effect". "Better-average-effect" and "Illusory superiority" are also used. Though "Superiority Bias" is used in a minority of papers, I think it's a clearer name.

Introductory reading: Chapter 14 of Cognitive Illusions; Chapter 5 of The Self in Social Judgment

Following quotes from Mark D. Alicke and Olesya Govorun (2005) "The Better-Than-Average Effect" in Mark D. Alicke et al. (Eds.) The Self in Social Judgment Psychology Press.

"Of the approximately one million students who took [the 1976 Scholastic Aptitude Test], 70% placed themselves above the median [i.e. in the top 50%] in leadership ability, 60% above the median in athletic ability and 85% rated themselves above the median in their ability to get along well with others. Amazingly, 25% of the students rated themselves in the 1st percentile on this latter characteristic."
"95% of the faculty [of the University of Nebraska] considered themselves above average in teaching ability and 68% placed their teaching abilities in the top 25%." (Cross (1977))
"88% of American college students, and 77% of Swedish college students, considered themselves to be above the 50th percentile on driving safety." (Swenson, O. (1981) "Are we all less risky and more skillful than our fellow drivers?" Acta Psychologica, Volume 47, Issue 2, February 1981, Pages 143-148 doi:10.1016/0001-6918(81)90005-6
Students given fictional proportions of times other students engage in postiive behaviours (e.g. co-operation). Actually the figures are the numbers that same student has used to describe their own behaviour in a previous study, weeks earlier. They still describe themselves as behaving positively more often than the average student. (Alicke et al. (2001))

Some references from David Dunning et al. (1989) "Ambiguity and self-evaluation: The role of idiosyncratic trait definitions in self-serving assessments of ability." Journal of Personality and Social Psychology. Vol 57(6) 1082-1090 doi:10.1037/0022-3514.57.6.1082:

"Management students consistently overestimated their abilities; in a marketing exercise, they indicated that a hypothetical firm, of which they were sales managers, would quickly overtake established competition. Executive Ss also predicted inordinate success." (Larwood, L. and W. Whittaker (1977) "Managerial myopia: Self-serving biases in organizational planning." Journal of Applied Psychology. Vol 62(2) 194-198 (text taken from abstract)) doi:10.1037/0021-9010.62.2.194

A follow-up from the Swenson (1981) driving skills study (mentioned above) found that, from a sample of 178 men and women drivers, "up to 80% [rated] themselves above average on a number of important characteristics, but also [...] rated themselves below 'a very good driver.' The ratings did not vary significantly across demographic categories." McCormick, Iain A., Frank H. Walkey and Dianne E. Green (1986) "Comparative perceptions of driver ability— A confirmation and expansion" Accident Analysis & Prevention. Volume 18, Issue 3, June 1986, Pages 205-208 doi:10.1016/0001-4575(86)90004-7

For more about superiority bias and driving, see my blog post "Why are there so many idiots on the road?"

In Nudge, Richard Thaler writes about an anonymous survey he conducts which asks his students where they expect to end up in the grade distribution at the end of the course:

"Typically less than 5 percent of the class expects their performance to be below the median (the 50th percentile) and more than half the class expects to perform in the top [20%]. Invariably, the largest group of students put themselves in the second decile [i.e. the top 20% but not the top 10%]"

Justin Kruger and David Dunning (1999) "Unskilled and Unaware of It: How Difficulties in Recognizing One's Own Incompetence Lead to Inflated Self-Assessments" (Full Text PDF) Journal of Personality and Social Psychology, Vol. 77, No. 6. 1121-1134

This paper reports four experiments, in which subjects (university students) had to take tests which would be marked objectively, then evaluate their own performance (in terms of objective score and how well they did compared to their peers):

Judging how funny jokes are (the "objective" measure was achieved by combining the expert judgements of several professional comedians)
Logical reasoning
Grammar (judging whether sentences are grammatically correct)
Logical reasoning (a conditional rule task)

In all of these tests, the worst-performing quarter (i.e. the bottom 25%) showed an enormous superiority bias, rating themselves above the median (i.e. in the top 50%).

There is much more to this study, but as a demonstration of the existence of superiority biases, it is especially clear.

Constantine Sedikides and Aiden P. Gregg, (2003) "Portraits of the Self" in Sage handbook of social psychology

"By and large, people hold flattering views of their own attributes. Most university students, for example, regard themselves as well above the 50th percentile in the degree to which they exhibit such sought after attributes as social grace, athletic prowess, and leadership ability (Alicke, 1985; College Board, 1976–77; Dunning et al., 1989).

"[People believe] that a greater number of positive life experiences (such as having a gifted child or living to a ripe old age) and a lesser number of negative life experiences (such as being a victim of crime or falling ill) lie in store for them than for similar others (Helweg-Larsen and Sheppard, 2001; Weinstein, 1980; Weinstein and Klein, 1995). Such unrealistic optimism is extended, albeit to a lesser degree, to others closely linked to the self, such as friends (Regan et al., 1995). In addition, people both overestimate their ability to predict the future (Vallone et al., 1990) and underestimate how long it will take to complete a variety of tasks (Buelher et al., 1994). As if that were not enough, people also overestimate the accuracy of their social predictions (Dunning et al., 1990)."