It's another way that social anxiety manifests, as a lower level filter. It's how mine generally shows up, and used to be much worse before I did a bunch of therapy.

One thing that made this being anxiety based very clear was that one night I took phenibut for a party, and the following morning it was still in effect and I found myself thinking of way more jokes and doing little improv reactions to the people I was talking to. It's like my brain was completely filtering them out due to very low level anxiety. I got lucky and the effect partially persisted afterwards, because it taught me that saying these things was safe, so I didn't have anxiety about them afterwards.

I used to have this pretty bad. I believed that it showed that I was autistic, or lacking some kind of fundamental creative spark, or something like that. It’s gotten a lot better since I got treated for depression and anxiety. I think it was really just me shutting down ideas at a pre-conscious level. I don’t know much about how the brain works. But this is my (pseudoscientific BS) mental model of it:

1. Our ideas and memories are composed of connections between neurons.

2. “Creativity” is the expression of random, new connections between those neurons.

3. Creative expression requires focusing our attention on those new neural pathways, filling them in and adding detail.

4. Depression and anxiety caused me to focus my attention on the idea of failing to come up with something “on the spot” (and the many minor traumatic memories of failing in this way), instead of the infinite weak, undeveloped ideas that could be explored with a moment’s focused attention. It’s hard to be fun when you are having a small anxiety attack.

5. The antidepressant I’m taking has gotten me out of this rut. Whether it’s by turning off my anxiety, or helping my nascent creative neural pathways reach further by preventing the reuptake of some neurotransmitter, I don’t know.

I think it's related to the exploration exploitation tradeoff in reinforcement learning. Creativity is related to exploration and randomness (and a high learning rate) while exploitation to using past knowledge to extract the maximum benefit. The brain switches off the creative/learning part in order to maximise the latter. In reality we need a mix of both, exploration is necessary for improvement and exploiting past knowledge is necessary for achieving high rewards. In neural nets, a too high or too low learning rate would not lead you to the optimum, you need to find the exact sweet spot. Anxiety would turn the balance too much into exploitation mode when we need to be creative.

The fight-or-flight response has a physiological effect on cognition:

> we suggest that stress shifts higher cognitive processing in a way that facilitates both engagement with and/or avoidance of the current stressor (i.e., fight or flight). By impairing executive control of cognition (i.e., working memory, cognitive inhibition, and cognitive flexibility), stress contributes to a reactive cognitive state that is fine-tuned to rapidly consider highly salient (i.e., stressor-related) information

> stress reallocates limited executive resources in adaptive ways [...] by impairing executive control over thoughts but improving executive control over motor actions [...] ideal for either fighting with or fleeing from a current stressor.

--- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5003767/

"Nothing"[1]

[1] https://www.youtube.com/watch?v=Ob4ZmHKbD28