The paper provides a summary of our recent research on preverbal infants (using violation-of-expectation and observational learning paradigms) demonstrating that one-year-olds interpret and draw systematic inferences about other's goal-directed actions, and can rely on such inferences when imitating other's actions or emulating their goals. To account for these findings it is proposed that oneyear -olds apply a non-mentalistic action interpretational system, the 'teleological stance' that represents actions by relating relevant aspects of reality (action, goal-state, and situational constraints) through the principle of rational action, which assumes that actions function to realize goal-states by the most efficient means available in the actor's situation. The

Behavior may be controlled by reactive systems. In a reactive system the motor output is exclusively driven by actual sensory input. An alternative solution to control behavior is given by “cognitive ” systems capable of planning ahead. To this end the system has to be equipped with some kind of internal world model. A sensible basis of an internal world model might be a model of the system’s own body. I show that a reactive system with the ability to control a body of complex geometry requires only a slight reorganization to form a cognitive system. This implies that the assumption that the evolution of cognitive properties requires the introduction of new, additional modules, namely internal world models, is not justified. Rather, these modules may already have existed before the system obtained cognitive properties. Furthermore, I discuss whether the occurrence of such world models may lead to systems having internal perspective.

Time is a fundamental dimension of cognition. It is expressed in the sequential ordering of individual elements in a wide variety of activities such as language, motor control or in the broader domain of long range goal-directed actions. Several studies have shown the importance of the frontal lobes in sequencing information. The question addressed in this study is whether this brain region hosts a single supramodal sequence processor, or whether separate mechanisms are required for different kinds of temporally organised knowledge structures such as syntax and action knowledge. Here we show that so-called agrammatic patients, with lesions in Broca’s area, ordered word groups correctly to form a logical sequence of actions but they were severely impaired when similar word groups had to be ordered as a syntactically well-formed sentence. The opposite performance was observed in patients with dorsolateral prefrontal lesions, that is, while their syntactic processing was intact at the sentence level, they demonstrated a pronounced deficit in producing temporally coherent sequences of actions. Anatomical reconstruction of lesions from brain scans revealed that the sentence and action grammar deficits involved distinct, non-overlapping sites within the frontal lobes. Finally, in a third group of patients whose lesions encompassed both Broca’s area and the prefrontal cortex, the two types of deficits were found. We conclude that sequence processing is specific to knowledge domains and involves different networks within the frontal lobes. Key words: sequence processing, frontal lesion, neuropsychology