It is estimated that by 2020, 2.95 billion people will be using social networks. But while sites like Facebook revolve around the wholesome concepts of friends, likes and shares, they have also become a way for people to cheat on their partners.
The problem is so rife, it seems, that suspicious partners are breaking into their other half's social accounts to find out if they are cheating. One survey of 2,400 UK adults who had cheated or been cheated on found that infidelity in 23% of relationships was exposed when Facebook was checked for evidence.
Though online social media is a relatively new phenomenon, cheating and the jealousy that people feel over it is practically ancient. We all know that snooping through messages is a serious invasion of privacy – whether the other person is being deceitful or not – but this high statistic shows how strong an influence jealousy can have on human behaviour.
Suspicion and jealousy
But is jealousy such a bad thing? Psychology professor David Buss compellingly argued that jealousy is a crucial emotion which evolved to help protect against relationship termination. According to Buss, jealousy motivates behaviour to either ensure sexual exclusivity, or to protect offspring against the loss of vital requirements, such as food, and against inclement weather and predators. These would have been critical prerequisites for the survival of our children during our evolutionary past.
According to this theory, losing sexual exclusivity would have been costlier for men, as his partner's engagement in sexual infidelity could result in his rearing another man's child. So men have evolved to be more sexually jealous.
By contrast, the theory states that securing vital resources would be more important for ancestral women in order to ensure the survival of her offspring. So a male partner's emotional involvement with another woman would inevitably mean the diversion of resources away from her to her rival. This means that women have evolved to be more emotionally jealous.
This is precisely what Buss and colleagues confirmed in 1992 when they asked participants in a study to imagine two scenarios. The first was that the participant's partners were involved in a sexual liaison with someone else. The second scenario revealed that their partner was involved in an emotional liaison with another person.
Buss found that significantly higher numbers of men would opt for the sexual scenario as being more distressing (60% compared to 40% of women) while significantly higher numbers of women (83% compared to 17% men) said that the emotional scenario caused more distress. Similar differences in gender responses were also found when Buss measured physiological arousal to hypothetical scenarios which revealed either sexual or emotional infidelity.
Subsequent research using different methods and participants from different cultures, have confirmed these gender differences when it comes to relationship jealousy. And through my own research, I have been applying what we know about this ancient emotion to the technological age.
As technology has given us unprecedented access into each others' lives, some say relationships have changed fundamentally – but does the same apply to how we feel jealousy?
To explore this, I have used fictional but realistic Facebook or Snapchat messages either sent by one's own partner or received from a rival, in several studies. The messages reveal either strictly sexual or strictly emotional infidelity, and participants were asked to imagine how distressed they would be upon their discovery.
The first study, published in 2015, used an eye-tracker to record where and for how long visual attention was focused on the messages. We found that male participants were clearly biased towards viewing Facebook messages which revealed their partner was being sexually unfaithful. Female participants focused attention more on the messages which revealed emotional infidelity.
In subsequent research, we presented participants with realistic, infidelity revealing, Snapchat messages (Snapchat has been shown to generate more jealousy than Facebook). We then invited them to imagine how distressed they would be if they discovered either an outgoing message or a received message which revealed unequivocally sexual, or unequivocally emotional, contact.
As well as finding the traditional gender differences, we also found that women were more distressed by messages received from "the other woman" than they were by messages sent by their partner, and when compared to men discovering incoming messages. These findings support previous work that collectively suggests women may be disproportionately and unjustifiably blamed for infidelity.
In other, unpublished research we found that the "identity" of the rival influences distress levels. For example, men appear less distressed by messages revealing infidelity between their partner and their own brother than they would if it was a stranger or a friend.
So what does all this mean? French critic John Baptiste Alphonse Karr once said "the more things change, the more they stay the same". This would most definitely apply, it would appear, to jealousy. Changes associated with the technological age have done nothing to tame the ancient green-eyed monster within us all.
Explore further: Are we still jealous? Infidelity in the age of social media