What's faster for humans: searching by color or shape? Why do we notice small icons in the corner of screens? Why it is hard to manage interruptions in our daily jobs? We design digital products and we sell pixels. Yet, we should remember they are meant for humans. In this presentation I am gonna address how well known mechanisms of cognition (like pattern recognition, peripheral attention and working memory) impact the way we perceive user interfaces. Getting to know these mechanisms will help you improve the way you design products.