Before speaking or acting, sally examines a situation for cues of how she should react, and then tries to meet the demands of the situation rather than act on her own feelings. she is probably a

she is probably a "High self-monitor".

Self - monitoring means the idea which was proposed by Mark Snyder in the late 20th century. This idea explains that to what extent people monitor their self-presentations and other behaviors. The quality is known to be a personality trait which allows one to accommodate into various social situations. High self-monitors as explained the case above monitor their situations and alter their conduct accordingly while low self-monitors do not do that.