There are two ways philosophers have distinguished intentionality: 1. intentional sign (or true intentionality): mental representation of a goal to be attained or a certain effect to be produced, and 2. intentional act (or intentional communication): an awareness that one’s behavior can produce outcomes or effects in general. Sometimes referred to in the psychology of learning as ‘contingency awareness’ or perceiving that reactions made by objects or other people are contingent on your behavior (i.e., what you do). In other words, it is perceiving that your behavior is effective in producing a change in the world around you. The question then is how intentional signs develop from intentional acts. For Piaget, this occurs by mean of circular reactions going from primary (repetition of movements that produce interesting ‘spectacles’ or events; stage 2 sensorimotor period, 1.5-4 months), secondary (awareness of relationship of own actions to environment, cf. contingency awareness; stage 3, 4-8 months) and tertiary circular reactions (deliberate variation of problem-solving means = experimentation with different means to obtain the same end state or outcome (stage 5, 12-18 months). Kenneth Kaye would subscribe to this view of how intentionality develops, but differs from Piaget in emphasising the role of caregivers in promoting it as in his apprenticeship model. In this latter respect, Vygotsky’s Zone of Proximal Development is very similar to Kaye’s apprenticeship model and what others have called ‘guided participation’. In contrast, Colwyn Trevarthen assumes ‘intentionality’ (which he sometimes refers to as motivations for action) to be a ‘given’ at birth and it is the starting point for his theory of development and in this respect he distinguishes between two exclusive modes of intentional actions: the communicative and the praxic modes. However, it is not clear from his writings when he is referring to intentional actions and when to intentional signs.