The main goal of the research is to get evidence to address the following issues: (1) What is the relationship between the Zone of Actual Development (ZAD) and the Zone of Proximal Development (ZPD)?, (2) Is the effect of the tasks joint solving relatively durable?, (3) Does the ZPD have predictive values for the future achievement over and above of ZAD?, and (4) What is more important for the prediction of future achievements - affective-motivational or cognitive help in joint solving? The experiment with parallel groups with 126 subjects is realised. Experimental treatment is consisted of solving of Raven matrices items with a gradual help given by experimenter according to previously defined plan. The results suggest: (1) there is positive and low correlation between ZAD and ZPD, (2) the effect of joint solving is relatively durable, (3) ZPD is significant predictor of future achievements over and above of ZAD, and (4) affective-motivational aspect of joint activity has stronger influence on future achievements than cognitive one.