Humans struggle to differentiate imagination from reality

The more vividly a person imagines something, the more likely it is that they believe it's real, finds a new study by UCL researchers. The research, published in Nature Communications , involved over 600 participants who took part in an online experiment, where they were asked to imagine images of alternating black and white lines while looking at a computer screen. After they imagined a stimulus, participants then had to report how vividly they were able to visualise it. Then, without the participant's knowledge, at the very end of the experiment, an actual stimulus with the same features as those the participant was imagining was gradually faded in to view on the computer screen. Participants then had to rate how vividly they imagined the stimulus and described whether what they saw was real or imagined. The results showed that the imagined and perceived stimuli became intermixed in the participants' minds. For example, when a real stimulus was faded in, participants believed that their imagination had simply become more vivid.