A University of California study has suggested that colours can be associated with body postures. Blue was associated with a relaxed figure, red with an angy or violet figure, re/yellow with a dancer and blue/green with a welcoming, thinking or searching figure (depending partly on the tone).
The Reciprocity Effect: How Strategic Favors Create Powerful Relationships
That free cheese cube creates an invisible thread of obligation—the same primal mechanism that once ensured tribal survival now shapes your shopping cart.