The human brain is the equivalent of the peacock's tail -- a "courtship device" that has evolved to attract dating partners, according to the Social Issues Research Centre (SIRC), in the article "What Social Science Can Tell You About Flirting and How to Do It." Unfortunately, unlike the peahen, women do not have an obvious colorful signal identifying the guys who are interested in having a conversation with them. For this reason, women must play detective and look for other aspects of an interaction to determine a man's intent.
It's in the Eyes
In the "Psychology Today" article "How to Get a Guy's or Gal's Attention," social and personality psychologist Jeremy Nicholson reports that men who are interested in getting to know a woman will use eye contact to signal this intent. Researchers at the SIRC concur, noting that in a crowded room full of strangers, eye contact that lasts more than a second can signal a desire to talk. In particular, if a man looks your way again after breaking his gaze, the odds are likely that he is interested in a conversation.
If a man does approach you, the distance at which he stands can be used as a barometer of his interest in getting to know you better. The SIRC divides the distance between two people into "zones": the "social zone" being anything greater than 4 feet, the "personal zone" being between 18 inches and 4 feet, and the "intimate zone" being anything closer than 18 inches. Although there is more leeway if a guy is standing beside you instead of in front of you (side-by-side encounters are less intimate), if he is within 4 feet and leaning in, there is a good chance he is trying to start a private conversation with you.
If a guy offers an "impersonal interrogative comment," such as "Nice day out today, isn't it?" or "Bit crowded in here, don't you think?" this is a concrete signal that he wants to start a conversation. According to the SIRC, these types of comments are easy conversation starters because they aren't too personal, and they imply a question without demanding a response. In other words, your guy isn't really that interested in your opinion on the impending storm or how many people are at the holiday party -- he just wants to talk, and these are safe topics with which to start.
If you still aren't sure if a guy is trying to start a conversation with you -- consider the venue or setting. If the two of you are at a party, in a college class, at work or playing a team sport -- these situations are ripe for new beginnings. That doesn't mean the guy at the deli counter doesn't want to chat or that your dentist isn't really interested in what you did over the summer -- just that the odds are less in your favor. When a guy appears interested in chatting in a social setting, it is much easier to discern the intent behind his behavior.