Change deafness

There's a thing called Change Blindness that suggests the brain is not always capable of 'seeing' changes. Derren Brown makes regular use of this mind trick.

New research suggests a similar thing occurs for sounds as well, a so called Change Deafness. The researchers tested whether we would notice if the person we were talking to on the telephone had changed mid-conversation. The scary thing is that apart from obvious changes such as male/female, most of us don't notice such a change at all.

The research team had participants interviewed via the phone. They were initially greeted by a female who explained that they would be asked twelve questions. After the third question the interviewer changed without warning.

After the final question the participants were passed to a 'supervisor', who quizzed the participant about whether anything unusual had happened during the interview, or whether they'd noticed a change in the interviewers voice.

Amazingly in the first experiment just 6% of participants noticed the change, whilst in the 2nd experiment just 4% did. Of those that noticed the change, none of them mentioned it during the interview itself.

Interestingly after the interview they were played a tape of the two interviewers and asked to pick who they thought had interviewed them. Remember that most of them thought they were interviewed by just one person. What's interesting is that opinion was split almost 50/50 between the two women.

"If language use evolved in service of face-to-face conversation … There is no reason for language processing to develop an alarm mechanism that would continuously monitor the talker's identity and automatically signal a talker change," the researchers said. "Given the assumption of interlocutor stability, listeners are free to focus attention on the linguistic message."

So basically evolution hasn't really equipped us for communicating without visual cues to aid us, hence we get change deafness.