Theory of Mind: Evolution of Terminology and Conceptualisation

Theory of Mind (ToM) refers to the ability to attribute mental states—such as beliefs, intentions, and emotions—to oneself and others, enabling social understanding and interaction (Green et al. 2015; Poletti et al. 2012). It consists of two primary components: cognitive ToM (reasoning about thoughts and beliefs) and affective ToM (reasoning about emotions), which interact but function separately (Shamay-Tsoory 2011; Sprung et al. 2022).

Conceptual and Terminological Challenges

Despite its importance in social cognition, ToM has been subject to ongoing definitional ambiguities and inconsistencies. Various scholars have debated its distinction from related constructs such as empathy and mentalisation. Some researchers conceptualise ToM as a discrete ability (present or absent), while others see it as part of a broader metacognitive system (Vegni, D'Ardia, Torregiani 2021).

Quesque et al. (2024) highlight the extensive and inconsistent terminology in mental state attribution research, where overlapping terms—such as ToM, mentalising, and mindreading—create confusion. Different disciplines apply the same term to varying concepts or use different terms for the same phenomenon, hindering comparability and theoretical progress. To address this, they advocate for a standardised taxonomy similar to efforts in emotion research (Kleinginna & Kleinginna 1981).

There are currently two main definitions of "theory of mind" in the literature. One of these definitions refers to the ability to attribute mental states (i.e., mentalising), while the other refers to a theory-specific term for the hypothesis that thinking about the mental states of others involves a set of concepts and principles about how these concepts interact. Quesque et al. (2024) recommend using “ToM” exclusively to refer to its second meaning. They suggest redefining ToM as the use of folk psychological knowledge to interpret mental states, distinguishing it from general mentalising, which refers to attributing mental states without necessarily employing a theory-driven approach. Having a theory of mind would thus indicate one particular mode (among many) of mentalisation. Importantly, this definition is consistent with the original use of "theory of mind" in ethology, where it was seen as a theory held by individuals rather than as an ability (Premack & Woodruff 1978).

Theoretical Perspectives on ToM

Theories explaining ToM's underlying mechanisms remain debated. Two dominant models include:

Theory-Theory – Posits that individuals develop ToM through learned principles about how mental states influence behaviour. (Premack & Woodruff 1978).

Simulation Theory – Suggests that ToM arises from simulating others' mental states by internally replicating their experiences (Gallese & Goldman 1998). Evidence from mirror neurons, which activate both during action execution and observation, supports simulation-based mindreading.

ToM in Research and Application

Since its introduction by Premack & Woodruff (1978), ToM has been extensively studied in human development, nonhuman animals, and clinical conditions, including ASDs. However, methodological inconsistencies in assessing ToM persist (Schaafsma et al. 2015). They propose a two-stage approach: deconstructing ToM into its fundamental cognitive components and then reconstructing a scientifically rigorous framework.

While ToM remains central to understanding social cognition, the field lacks a unified conceptualisation. Establishing clear, standardised definitions would enhance research clarity and interdisciplinary collaboration.