Unravelling the small number bias: the role of pseudoneglect and frequency of use in random number generation

When asked to produce random numbers individuals generate more small numbers than large ones, a phenomenon known as “Small Number Bias” (SNB; Loetscher & Brugger, 2007). This bias has been associated with a spatial preference known as “pseudoneglect,” where attention is biased towards the left side of the mental number line during numerical processing (Loetscher & Brugger, 2009). Another potential explanation for SNB is the higher frequency of use of small compared to large numbers in daily life (Dehaene & Mehler, 1992). This study aims to determine which of these two explanations better accounts for SNB. Participants were asked to generate random numbers from 1 to 12 while viewing either a regular or an inverted clockface. On a regular clockface smaller numbers are on the right, whereas on an inverted clockface they are on the left. Both theories predict SNB for the inverted clockface. However, for the regular clockface, frequency of use would predict SNB, while pseudoneglect would predict a bias towards larger numbers. Results showed SNB in the inverted clockface condition, but no bias in the regular clockface condition. These findings suggest that SNB arises when pseudoneglect and frequency of use align but is absent when they conflict. Overall, the results indicate that both pseudoneglect and frequency of use contribute to SNB in some degrees.