2014 Reprint of Original 1960 Edition. Exact facsimile of the original edition, not reproduced with Optical Recognition Software. Most of Berlyne's research and writing focused on the effects of and reactions to curiosity and arousal. His work focused on "why organisms display curiosity and explore their environment, why they seek knowledge and information". He believed that objects impact on three levels, psychophysical, environmental, and collative. The last of these was a term coined by Berlyne which attempted to describe the hedonic levels of arousal fluctuation through stimuli such as novelty, complexity, the element of surprise and incongruity. Ultimately, he believed that arousal was best and most effective when at a moderate level and influenced by the complexity and novelty of the arousing object. His work remains influential to this day.