The widespread misconception that psychology is easy and mere common sense has its roots in the biased way that children work out whether a topic is challenging or not.
Frank Keil and colleagues asked children aged between five and thirteen, and adults, to rate the difficulty of questions from physics (e.g. How does a spinning top stay upright?), chemistry, biology, psychology (e.g. Why is it hard to understand two people talking at once?) and economics. The questions had been carefully chosen from earlier pilot work in which they'd all been rated as equally difficult by adults.
Consistent with the pilot work, the adults in the study proper rated the questions from the different disciplines as equally difficult. However, children from age 7 to 13 rated psychology as easier than the natural sciences - physics, chemistry and biology, which they rated as equally difficult.
Young children can't possibly have the depth of understanding to know which scientific questions are more difficult. Instead they must resort to some kind of mental short-cut to make their verdict. Keil's team think that children's feelings of control over their own psychological faculties - memories, emotions and so forth - and the superficial familiarity of those kinds of concepts, likely lead them to believe psychological concepts are easier to understand.
A second study provided this account with some support. This time children and adults rated the difficulty of questions from within the various branches of psychology. Similar to the first study, the children, but not the adults, rated questions related to social psychology, personality and emotions as progressively easier, compared with questions related to cognition, perception and biological psychology, which they rated as progressively more difficult.
So, when do these childish misconceptions leak through into adult judgments? For a third study, another batch of children and adults were again presented with the same questions from the different scientific disciplines, but this time they were asked to say whether they would be able to solve each question on their own (or require expert help) and to estimate what proportion of the adult population would know the answers.
This time the adults as well as the children tended to say they could solve more psychology questions on their own, compared with questions in the other sciences, and kids and adults estimated that more people knew the answers to the psychology questions. Remember these were psychology questions that adults had already rated as just as difficult and complex as questions in the other sciences. 'Such biases [towards seeing psychology as easy] may be observed when tasks do not so directly ask about difficulty of understanding and instead use measures such as ease of learning on one's own,' the researchers said.
Keil's team said their findings have real-life implications, for example in the court-room. 'If psychological phenomena are seen as usually quite easy to understand and largely self-evident and if such judgments are inaccurate and underestimate the need for experts,' they warned, 'cases might well be decided in ways that unfairly exclude valuable expert insights.'
In fact, the researchers pointed out that such situations have already occurred. In the US trial of former Presidential Assistant I. Lewis 'Scooter' Libby, for example, the judge disallowed the use of psychology experts on memory, on the basis that the jury could rely on their common sense understanding of memory. This is particularly ironic given that prior psychology research has shown that jurors and judges have a woefully poor understanding of how memory actually works.
Keil FC, Lockhart KL, & Schlegel E (2010). A bump on a bump? Emerging intuitions concerning the relative difficulty of the sciences. Journal of experimental psychology. General, 139 (1), 1-15 PMID: 20121309
Related article in The Psychologist magazine: 'Isn't it all just obvious?'