The novel “Fifty Shades of Grey” introduced BDSM into polite public discourse – and now the movie version is set to be in theaters by Valentine’s Day.

If you’re wondering who in real life does this stuff and what effects it has on people, NIU psychology professor Brad Sagarin has some answers.

Sagarin, who conducts human sexuality research, blogs on the topic of BDSM on the Psychology Today website. The blog provides answers to five kinky questions, including: “How many people are into S&M?”

NIU psychology professors are regular Psychology Today contributors. They’ve been blogging monthly on the site for nearly two years.

Other blog entries have included:

• “A Look at Effects of Stimulant Treatment on ADHD”
• “Parenting a child with autism: resisting pressure, finding success”
• “Love 2.0, Actually, Is All Around”
• “More study needed on possible role of pot in psychotherapy”
• “Women Helping Women in the Workplace – Or Not?”
• “Demonstrating how subtle features of language might influence juror decisions”
• “Why exercise boosts both body and mind”
• “The Science Behind the New Year’s Resolution”
• “Too Tired for Good Behavior?”
• “When Does Teasing Go Too Far?”
• “How Old Are You? On the Job, It’s Not So Obvious”
• “Why Do Some Kids Cyberbully Others?”