**2.2 Description**

Since behavior is a continuous process, it is necessary to build a system of units that breaks down this continuity and digitizes it. This amounts to dividing the observed behavioral flow into motor acts, the various possibilities of which are described over time.

The behavioral reading instrument consists of establishing a repertoire, in terms of action verbs, according to a vocal-mimo-posturo-gestural vocabulary (e.g., "raise the arm," "lower the head," "turn the body to the right," "darken the eyebrows," "smile," "speak to," "give an object to," etc.). The ethologist builds a digitization instrument corresponding to different levels of description (microscopic vision, macroscopic vision).

The description tool is the direct input in the field or the delayed input of video recordings collected in a situation.

#### **2.3 Quantification**

The numerical tool measures the probability of occurrence of each act in the repertoire, by counting these manifestations in terms of frequency, duration, or sequential order, replacing each behavioral unit in its functional framework and in its own space. It allows this complexity to be represented by multivariable processing. The quantification of the observed behavior is then translated into occurrence frequencies (absolute or relative), transition frequencies, and association frequencies. The duration of the items is also measured in the behavioral sequence. A spatial mapping into digitized units is performed in the same way. We obtain a scheme of use of space combining space, time, and activity.

#### **2.4 Computer support**

A software-based solution for research in space ethology is called The Observer XT® software [7]. It is a professional system that can be used for the collection, analysis, and presentation of observational data. It allows annotation of behavioral descriptors through a traditional encoding process. Its technical specificity is the synchronization of video files with the collection of ethological data as state events or point events, and any other source of information such as psycho-physiological measurements and environmental parameters.

Right now, the interface between the human observer and *The Observer XT®* software is not computerized. Because of the complexity of the behavior to be analyzed, the ethologist's eye remains an essential tool. We can use techniques like the newly developed Facial Action Coding System [8] first adopted by psychologists [9]. It is a common standard to systematically categorize the physical expression of emotions, but it does not integrate the behavioral activity from the human repertoire as a whole, that is, in egocentric references (with regard to the subject), allocentric references (with regard to the other subjects), and geocentric references (with regard to the three-dimensional environment).
