Two-system theories of social cognition defend the view that social cognitive processes can be broadly distinguished into fast, relatively inflexible routines that may occur without any awareness (System 1) and slow, flexible routines, which require the expenditure of mental effort and are subject to consciousness and deliberative control (System 2). I am defending a two-system pluralist approach to social cognition. Domain-specific social cognitive as well as domain-general cognitive processes can be broadly separted into two systems. Some processes are cognitively less effortful and than others. All things being equal, human cognition works in an economic manner so that individuals typically go for that (social) cognitive strategy in a given situation of social understanding that is cognitively least effortful to them.
The role that fluency, i.e. the subjective experience of ease associated with completing a mental task, plays in social cognition can be illustrated by using the example of 4- to 5-year-olds'
reasoning in explicit versions of the true and the false belief task. For decades, philosophers and psychologists have assumed that children understand other people’s behavior on the basis of Belief
Reasoning (BR) at latest by age 5 when they pass the false belief task. Furthermore, children’s use of BR in the true belief task has been regarded as being ontogenetically prior. Recent findings
from developmental studies challenge this view and indicate that 4- to 5-year-old children make use of a reasoning strategy, which is cognitively less demanding than BR and called perceptual access
reasoning (PAR), in true belief tasks. I appeal to research on
fluency to explain these findings. On my account, 4- to 5- year-old children understand other people’s behavior by means of BR if they experience cognitive strain (such as in false belief tasks) but they revert to simpler heuristics PAR when such an experience is missing (such as in true belief tasks) (Fiebich 2014).