Machiavellianism is a personality trait that reflects how likely a person is to think that manipulation of others is the solution to their problem.

It is measured by the MACH-IV personality test on a scale from 20 to 100. I have taken all of the responses collected and broken them down by age to see how growing older affects a person.

It seems people appear to be less machiavellian the older they are.

I pulled data from the Taylor Manifest Anxiety Scale and have graphed it by age.

Scores on the Taylor Manifest Anxiety Scale by age, they are around 35 in the teens and trend downwards.

A clear downward trend! It looks like there might be reason to look forward to growing old.

So, I found an interesting claim:

British journalist Jon Ronson is obsessed with obsessives. He’s best known for writing the book behind the George Clooney film “The Men Who Stare At Goats.” In his latest book, Jon Ronson has turned his own obsessive eye toward psychopaths. The book is called “The Psychopath Test.”


One of the stranger characteristics of psychopaths is their choice of pets. Ronson says they are almost never cat people. “Because cats are willful,” he explains.

Psychopaths gravitate toward dogs since they are obedient and easy to manipulate. Ronson says he spoke with individuals who would qualify as psychopaths who told him they aren’t sad when they hear about people dying. “But they get really upset when their dogs die because dogs offer unconditional love.”

I was unable to find the justification for this claim with some searching and as such specific statements never tend to be very true, I thought this one should be put to the test.

To this end, I appended the question

If you had to choose, what would you describe yourself as?
A ‘dog person’.
A ‘cat person’.
I don’t want to answer.

to the end of the Psychopathy Scale as a “research item”. The scale is short questionnaire used for the study of psychopathy in adult populations. It can not diagnose psychopathy, but it correlates very well with the Hare Psychopathy Checklist which can. In measures two scales: primary psychopathy (things like arrogance, manipulativeness, callousness, lying) and secondary psychopathy (things like irresponsibility, impulsiveness, lack of long-term goals and boredom proneness).

Here are the results,

Answer Primary psychopathy Secondary psychopathy #
Dog person 2.44 2.67 304
Cat person 2.54 2.84 283
Didn’t answer 2.92 2.94 102

As can be seen, dog people actually scored lower for both dimensions of psychopathy than cat people, although not by much. The claim would appear to be wrong.

To tell if color cues can affect individuals answers on personality tests, the Narcissistic Personality Inventory was altered so that upon page load each user was served up a version with a random red component to the background color and scores were recorded. The colors in RGB notation, where a component can have a value between 0 and 255, were in the range (R=33, G=33, B=33) – (R=232, G=33, B=33).

Below are the average scores for 1861 test takers grouped by the hue they were assigned (from less to more red).

Scores on the NPI by amount of red in page background.

As you can see the trend line is exactly flat, indicating that the background color of a page does not affect how users answer the personality inventory.

The data used in this post can be download for reanalysis here.

The spinning dancer illusion, as seen on the right, was created by web designer Nobuyuki Kayahara in 2003. Because it lacks the visual cues used to determine depth, it can be seen as spinning in either direction.

Around 2007/2008 it was widely circulated as a right-left brain personality test. That the image can serve as a personality test has been dismissed by skeptics, which is reasonable as their is no evidence for the proposition. It would be nice to have a concrete answer though, so, to that end, the illusion was appended to the Big Five Personality Test as a “research item” and people who took the test were directed to indicate which direction they saw the image spinning (or were given the option not to answer).

In this time 934 of the test takers indicated their answers were accurate and suitable for research. The sample is 53% male; average age is 30.0 years; 72.1% saw the dancer spinning clockwise. The differences in their big five personality traits are tabled below.

Trait Average (clockwise) Average (counterclockwise) p
extraversion 3.08 3.07 0.84
conscientiousness 3.32 3.47 0.01
neuroticism 2.98 3.09 0.08
agreeableness 3.89 3.89 1
openness 4.08 4.02 0.22

There was one statistically significant difference (p<0.05), conscientiousness, but its effect size was minor. So, yes, the spinning dancer can serve as an indicator of personality, although an extremely minor one and not in a right-brain left-brain sort of way. The data used for the post can be downloaded for reanalysis here.