"Changes in heart rate and brain activity (EEG) were monitored in six heterosexual couples, in an established relationship, to compare the effects on brain and body of two forms of oral and olfactory stimulation – kissing and allowing chocolate to melt in the mouth." The brain waves measured were alpha waves, which are normally associated with pleasure and enjoyment.

It was found that, so far as both heart rate increase and brain wave amplitude are concerned, the effects of chocolate exceed those of a kiss." And the heart rate increased not only more, but stayed up for longer, with chocolate.

at least one couple, the man's heartrate was much more affected by kissing, the woman's by chocolate.