Social Space is a crux issue. It should be considered as the cornerstone of joint activities and hence to collaborative work/learning. This space is build considering the traces left in the environment (virtual or not) by people. We all send signals into social space that can be decoded by others as trace for a potential use. For instance, "following the leader" to the baggage claim is an action we often perform : in this case, we see somebody (the first guy who jump off the plane :) following a certain path (this is the signal). We decode this signal as a cue : this guy may be aware of the way one should follow to get to the baggage claim. According to Per Persson and Fredrik Espinoza's talk, there is to kind of social spaces :

- direct social space : synchronous interaction like one-to-one communication (face2face, chat), copresence of people, mutual awareness, use of shared artefacts... We don't really need to decode the trace since there are some "conventions" like verbal language, signs... - indirect social space : we need to decode the signal : following the leader as I explain above, fingerprints, others were here, public crowds, recommender systems, traces of group identity (uniforms, brands), tags and graffiti, annotations...

Furthermore, human beings are definetely social animals. We love living in social space and we're all observers (yeah this is linked to Piaget's constructivism :) who interprets others' signals.