One study asked heterosexual men how comfortable and anxious they are around gay men. Based on these scores, they then divided these men into two groups: men who were homophobic and men who were not. These men were then shown three four-minute videos.
One video depicted heterosexual sex, one depicted lesbian sex, and one depicted gay male sex. While this was happening, a device was attached to each participant’s penis. This device has been found to be triggered by sexual arousal but not other types of arousal, such as nervousness or fear. (Arousal often has a very different meaning in psychology than in popular usage).
https://pubmed.ncbi.nlm.nih.gov/8772014/
https://psycnet.apa.org/doiLanding?doi=10.1037%2F0021-843X.105.3.440
their ratings of erection and arousal to homosexual stimuli were low and not significantly different from nonhomophobic men who demonstrated no significant increase in penile response to homosexual stimuli. These data are consistent with response discordance where verbal judgments are not consistent with physiological reactivity, as in the case of homophobic individuals viewing homosexual stimuli.