how to perform nose touch assay

We are now doing nose touch behavior including-reversal、head withdrawal according to the following protocols:
For each strain, ten worms were allowed to move forward into an eyelash in the path of the worm. We repeated this ten times for each worm,
at least three trials per strain, and recorded either a reversal response, head withdrawal or null response.

Using N2 and trap-1 as a set of control,I have tried several times but no positive results.
:-\ :-\

you have probably already read through section 7 of this wormbook chapter?:

There are a number of variables that either diminish response in control animals or ablate it completely and that should be considered:

are worms hitting the hair at 90 degrees?

do you assay on thin lawns of bacteria vs. no bacteria or thick lawn of bacteria?

are you using an appropriately sized hair?

are you using the correct part of the hair?

are you wiping the hair between trials?

etc. etc.

It takes practice to get the assay to work reproducibly…