11 crucial point
– both from an experimental and theoretical point of view – is then to clearly define which aspects of action we are investigating and which components of motor
behaviour we expect to be affected i.e. planning, execution, temporal sequence of actions and so on.
0.2. Goals definition and motor chains
A critical role in defining an action is played by the so-called goal of an action. The recent definition given by Gallese 2009 where goals are defined in terms of
“value for the system”, and are structured along an axis of valence, can be very fruitful. However, we need to consider goals not strictly as the “aim” of a single subject or the final
effect of her actions. In fact, we need to achieve a more general definition of goal, if we extend it to the domain of intersubjectivity.
From this point of view, goals cannot be reduced just to the final end state of an action, or to the intention of a subject; rather they are what stands for the “value” of an
action. Broadly considered, the notion of value can refer to the social value, to the value for an individual in a given situation, or it can reflect the value of a single motor act sub-
goals with respect to the action in which it is embedded. This open definition of goal allows treating action organization at a very general level, where goals can be dynamically
modulated through another basic mechanism which received much attention recently: the structure of actions in motor chains see chapter 4.
Motor chains rely on the idea of motor acts i.e. the act of grasping as coded both per se with specific parameters and with respect to the chain in which they are embedded
in order to perform an action and to achieve a goal. For instance, the motor act of grasping can be embedded in the chain with the final goal to put a piece of food in a container or to
take it to the mouth. In this sense, each motor act depends on the one that immediately precedes it and all depend on the final act which leads to goal achievement. These
12 sequences of motor acts can be of different complexity, and several sequences can be
combined together. What is relevant is that each action is defined by a goal and a motor chain, but it is
just a syntactical description of that action, that is the other parameters such as the kinematics are differently defined and probably coded by different neural structures. In this
sense this constitutes a basic description of action which is easily translated from actual performed actions, to verbal language, gestural pantomimes, pictures and more. This is
particularly due to the fact that if chains constitute the syntax of actions, then the roles in the chains such as SubjectObject are empty and they are locally fulfilled for a single
action. This elaboration of motor chains permits to assume them as the basic mechanism
which allows for the passage between the single level of embodied processes and the level of intersubjectivity. The empty actantial roles can be easily fulfilled by more than a single,
even by a group, in defining just locally their position. In this sense a motor chain is a mechanism which accounts both for single-body processes and for intersubjective
relations. More, it supports our idea of a continuous translation between different languages and systems.
0.3. Experimental contribution: the structure of the thesis
