Probably half full, we’re hard wired to think positively.
Neuroscientist Tali Sharot has dedicated a large amount of time to investigating this very question, and her experiments have generated some very interesting results, which she has recorded in her book The Optimism Bias.
She recently recorded the brain activity of volunteers while they imagined future events, and then compared that activity with the pattern she saw when people recalled past events, and the results were surprising. While the volunteers remembered past events quite accurately, when they were asked to imagine an event that hadn’t happened they were much more likely to think positively. For example, one participant was asked to imagine a plane ride, so she thought of an enjoyable journey of an exhilarating take-off and subsequent nap – no delays, screaming babies or terrible food!