Driven mostly by convenience, wider choices and lower prices, more and more of us are now abandoning the high street in favour of the Internet. And where once we might have relied on the polished patter of a retail salesperson, we now have, via on-line reviews, access to the collective voices of hundreds of fellow consumers from around the world. But what type of people post these reviews and why? Why is it that some people feel compelled to post thousands, or even tens of thousands of on-line reviews, while the vast majority rarely or never do? Is it a fair system? What is the psychology behind it, and what are the ethical implications of posting good, bad, or indifferent reviews? Reciprocation I suppose the most obvious psychological motivation to post reviews is the rule of reciprocation. Having shopped on-line a few times before and benefited from the reviews left by others, some of us will feel a social obligation to contribute to the system which helped us. But how often and under what circumstances will we bother? My own experience is that I receive roughly one review of my book for every 300 or so downloads. Whether this is above or below the average, I have no idea, but I am nevertheless extremely grateful for every one – or at least most of them. Customer Advocacy In marketing circles, it has long been known that the most powerful advocate for any product is the customer. But not any customer will do. Imagine you have just bought...