Female rats wearing jackets are not unlike women in lingerie. Across all animal species, sexual behavior is directed by an intricate interplay between the actions of hormones in our brains. In a new quirky study, researchers adorned female rats with special jackets to better understand what turns male rats on. These findings, presented at the Society for Neuroscience annual meeting last month, could help answer the burning question: Why do men like lingerie?

A Concordia University team led by James Pfaus and Gonzalo Quintana Zunino has previously shown that that male rats can be conditioned to prefer ejaculating around females who bear a particular odor (almond, if you’re wondering). These males were rewarded during their post-ejaculatory state. The team also found that virgin male rats wearing a special rodent-tethering jacket during their first sexual experience lose sexual arousal and motivation if the jacket was removed before another act of copulation.

Together, those studies demonstrate how an odor becomes a partner-related cue and how the jacket acts as a contextual cue for sexual arousal. Now, the same team wanted to know if the rodent jacket could act as a cue to establish “conditioned ejaculatory preference” (CEP). That is, is the jacket a turn on?

In one experiment, 12 sexually-naïve male rats underwent 14 multi-ejaculation trials with females wearing the rodent jacket. During the final trial, the males were placed into an open field with two sexually receptive females: One donned the jacket, the other was in her birthday suit. More males ejaculated first with females wearing the jacket. They would also feel the jacket with their whiskers while mating.

In the second experiment, another dozen males were exposed sequentially to sexually receptive jacket-clad females and then to unjacketed, non-sexually receptive females. In the final open field test, the males ejaculated more, and more quickly, with the jacketed females. The team then examined the brains of these males, comparing them with brains of males who weren’t trained to associate a jacket with sex. Males who mated with jacket-wearing females, Live Science explains, showed more activity in the brain’s pleasure center.

Males, they find, can learn to associate somatosensory cues -- the feel and sight of particular outfits, in this case -- with sexual arousal. In other words, as Quintana Zunino tells Live Science, males learn that "each time my partner wears lingerie, I'm going to have sex."