My life with aphantasia
Catherine Salt has aphantasia - a little-known condition which means she can't picture things in her head.
It's thought about two per cent of the population are aphantasiac, but the condition was only given a name in 2015.
Catherine told BBC Radio 5 Live how it affected her at school and why it can have benefits.
This clip is originally from 5 Live on Thursday 3 August.