Most language use is fast and automatic. This would be run by Daniel Kahneman’s System 1 for cognition. This presumably includes conventional, non-deliberate metaphor use. But it may even include a lot of novel and/or deliberate metaphor use, as many experiments have shown that there is only a minimal (but significant) delay in their comprehension in comparison with conventional metaphors. People can do analogical thinking, including figurative analogical thinking, and even novel figurative analogical thinking, at a surprisingly fast speed.

However, metaphor can also be slowed down, in production, comprehension, and interaction. This happens when language users have difficulties in building the appropriate metaphorical meanings or pay special attention for whatever reason. For instance, when people are reading a literary text or are trying to understand a complex scientific model, they can give more attention to utterances involving metaphor. This would recruit Kahneman’s System 2.

This involves more voluntary (and slow) reasoning about analogical projections between domains. This is a process that presumably includes more precise mapping and testing of that mapping’s quality. It could also exhibit more frequent metaphor recognition, interpretation, and appreciation, which can generate a form of ‘metaphor awareness’. This is deliberate metaphor processing that is slow.