With an open posture, what could the body language of both parties look like?

An open posture speaks to a body language that communicates agreement with the other party(ies)  or the proposal or the argument being proposed an openness to interact with the other party(ies).

Explanation:

Examples of open posture include but are not limited to:

On the other hand,  

Crossed arms and or legs, distracted eyes, clasped palms etc all communicate signify discomfort and reluctance to share or continue with the conversation.

Body languages are important communication tools and can define or mar relationships. Master communicators are very keen on observing and responding to non-verbal communication.

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The spontaneous display of behavior even after withdrawing of the reinforcement is termed as resistance to extinction. In the circumstance of extinction, the behaviors, which no longer get reinforcements should no longer be possessed by the organism. However, in some of the cases the behavior can still exist even if the reinforcements are no longer provided. When this occurs, resistance to extinction takes place.