In behavioural experiments we studied the ability Macaca mulatta monkeys to perform cognitive tests with different levels of difficulty presented on a touchscreen. The task was to determine a dominant orientation within patterns ordered in different way. We analyzed learning rate, the number of correct answers and reaction time depending on the task complexity. At the same time we estimated investigatory activity by measuring time of reaction to a novel object. The percentage of the correct answers was higher for more ordered test images and close to the one obtained before for human subjects in similar experiments. The investigatory activity index correlated with the learning rate and was lower for those monkeys, who demonstrated longer response time and had a tendency for attention distraction. The results enable us to model neuronal processes occurring in the human brain during object recognition, from coding of image physical characteristics to decision making. The relationship between the level of investigatory activity and the learning rate makes the novel-object test a promising evaluative tool for choosing perspective monkeys for behavioural experiments, which can significantly reduce the time of training.