First impression are high variance
The idea that first impression matter can be interpreted in information theoretic terms. If Information is surprisal, variance and deviation from expectations are informative. Volatility is information, thus information sources with high variance are thus more informative than those with low variance, assuming the variance represents true signal rather than noise.
For first impressions to matter as much as people claim, they must be high variance. Otherwise, they wouldn’t be informative. So the statement that “first impressions matter” is simply a statement that first impressions are high variance.
This variance represents risk. If you want to control what people think of you, relying on making a great first impression is a very risky strategy, as it’s inherently a high variance information channel. This is partly why I write so much – I’ve found first impressions to be too unreliable and risky, and I’d rather tamp down the variance and exert more control over the impression I make on others.