The first model omits the random effect for meaning, and includes the random effect of salience; the second model includes random effects for meaning and salience; comparing both models tests the random effect of meaning (which we know already to be very small), not salience.
So, my proposal: the first model omits the random effect for meaning (which is a nuisance by a variance nearing zero), and also omits salience in order to find out whether salience is worth it to estimate; the second model includes the random effect for salience only; comparing both models tests the random effect of salience.
The first model omits the random effect for meaning, and includes the random effect of salience; the second model includes random effects for meaning and salience; comparing both models tests the random effect of meaning (which we know already to be very small), not salience. So, my proposal: the first model omits the random effect for meaning (which is a nuisance by a variance nearing zero), and also omits salience in order to find out whether salience is worth it to estimate; the second model includes the random effect for salience only; comparing both models tests the random effect of salience.