In a 2013 paper, Stanford researchers Dan McFarland and Dan Jurafsky analyzed the conversations of nearly 1000 heterosexual couples during speed dating encounters to find out why some people felt a sense of connection after the meeting and others didn’t.

The participants in the study were graduate students at Stanford, and wore audio recording devices during their dates. The dates lasted four minutes each, and after they were done, the participants filled out a scorecard that asked them to rate how connected they felt to each partner (“clicking”, on a scale of 0-10) and whether they would like to go on a real date with that person (“willingness”, on a yes/no basis).

The recordings of the dates were then transcribed and algorithmically analyzed (using computational linguistics techniques) to see if any characteristics of the words/speech corresponded to the participants’ reporting of feeling a sense of connection.

The researchers found that the following converasational behaviors were correlated with clicking:

  1. Conversational focus on the woman
  2. The man using appreciative (“Good for you”) and/or sympathetic (“That must’ve been tough for you”) language
  3. The man interrupting, if the intention is to exhibit alignment / understanding and not to control / redirect the conversation
  4. Not asking a lot of questions — women asked questions to keep a lagging conversation going and men asked questions when there was nothing else to say
  5. Shared stories
  6. Variance in vocal tonality, speed, and volume — indicates excitement

Interestingly, although traits (height, BMI, dating experience, country of birth) explain nearly twice as much variance in clicking as speech characteristics (15% vs. 7.5%) in the 4-minute context of the experiment, the paper states that the latter gains in salience and effect with each additional minute of communication.

Note that this study was done on graduate students, so results may not extend to regular people.