It is now commonplace to hear that addressing the grand challenges of today’s society – climate change, obesity, ageing populations, pandemics – requires substantial changes in individuals’ behaviour (e.g., Newell & Moss, 2021). This call to arms places cognitive and behavioral science at the forefront of understanding how such widespread change can be achieved. Answering that call has led many researchers to make bold claims for the potential of simple techniques that facilitate positive behaviour change without impinging on people’s freedom of choice (e.g., Thaler & Sunstein, 2008). These techniques, collectively and colloquially known as ‘nudges’ capitalize on promoting ‘desirable’ options by making changes to the choice architectures (physical, social and psychological) in which decisions are made.

The extent to which we generalize a novel property from asample of familiar instances to novel instances depends on thesample used. In these experiments, we are interested in twosample characteristics: number of types (discrete entities) andnumber of tokens (copies of the same entity) that share a novelproperty. Existing studies permit separate and conditionalhypotheses about the effects of adding types and tokens, but nostudy has examined the effects of both variables ongeneralization stimuli varying in similarity. We find thatadding types broadens generalization to similar stimuli, buttightens generalization to dissimilar stimuli. Adding tokensdoes not affect generalization, but adding repetitions that areframed as types produces some tightening. Implications formodels of inductive reasoning are discussed.