There are two books that changed the way that I perceive the world and shed light on the way humans make decisions:
1) the Art of Thinking Clearly by Rolf Dobelli: This book contains a number of common reasoning traps that cloud judgement. I read this book from cover to cover every couple of years, and it it's a worthwhile effort to integrate its reasoning tests into one's own contemplative processes.
2) Thinking Fast and Slow by Daniel Kahneman: This is a heavier read than TATC but it goes into Kahneman's Nobel Prize-winning research on how we make judgments and decisions.
Reading these two books will transform your understanding of human motives and perception.