In this study on the effect of communication on competitive and cooperative behaviour, 10 dyad groups and 10 groups of 3 members played the MDG, a non-zero sum game under communication after every 10th trial, and no communication conditions. It was concluded from results that communication, whether between groups or between representative of the groups, tends to increase a tendency of a person to change (feel repentant) from competitive moves to cooperative moves. The effect of partner's response or strategy was studied by playing the dame under four conditions: the other player or group being (a) unilaterally cooperative; (b) unilaterally competitive; (c) reciprocating; and (d) response opposite to the subject. Analysis of results showed that unconditional cooperation leads to exploitation and obduracy. This tendency was less in groups. Other interesting effects are described in the paper.