To put it another way, in general, as men aged their sports car ratings declined, but if they felt they had a small penis, they rated the rated the sports cars more highly, like younger men. But as participants aged above 30, there was an increasing difference between those who felt they had small and a large penis. For participants under 29, there was no real effect of penis size on ratings of cars. There was strong evidence that this difference was real when you look at all our participants (left panel), but when we plotted them by age another pattern emerged (right panel). This plot shows that when men felt like they had a relatively small penis (blue dots), they rated the sports cars systematically higher than those who felt they had a large penis (red dots).

But would that change what they felt about sports cars? Since we knew our participants, on average, would have penises of around 13cm like everyone else, we reasoned that this false information would make them feel relative well, or poorly, endowed. We did this by mis-informing them that the average size of other men's erect penis was either 18cm, or 10cm.

We created an online experiment with the Gorilla platform that made men believe that they had a relatively small or large penis, and then asked them how much they wanted a particular sports car. The solution was to use a psychological, experimental manipulation. Even if we could use a tape measure to find out the true size of owners of different car types, this would only give us a correlational picture. Sadly, only 12% of their partners shared that opinion. One survey found that 43% of car owners said they had a penis larger than average.

Penis owners are notoriously dishonest about reporting their size, and sports car owners even more so. We quickly realised that we couldn't answer this question with a tape measure or a survey.

Size of a gorilla penis