Shaking hands before negotiations results in a better deal for both parties - even when one is represented by a robot, a study has found.
The act of shaking hands at the start of a conversation has already been shown to create better cooperation and trust between humans.
Research has now found that these benefits extend when a robot takes the place of a human - who is situated remotely - during a business meeting.
Scientists say using robots provides a powerful two-way experience that allows people to have a physical presence in a distant place unlike using Skype or video conferencing.
Developing such interaction could lead to robots conducting business meetings or allowing people with severely limited mobility to interact with the world in a unique way.
The study, by the University of Bath, used NAO, a 58-cm tall humanoid robot which was designed to be a companion around the house, in mock real-estate negotiations.
One person - assigned the role of buyer or seller - was present in the meeting with NAO while the other took part in the meeting through the robot's inbuilt head camera and microphone.
Touch sensitive sensors in the robot's hand transmitted a signal when it was grasped, leading to a controller in the remote person's hand vibrate at the same time.
Results showed that the act of shaking hands was as important when people interacted virtually through the robot as when they met face-to-face.
The remote person, who could be thousands of miles away and essentially hidden from view, did not exploit their tactical advantage in such conditions.
Researcher Dr Chris Bevan, of the University of Bath's Department of Psychology, said: "This experiment highlights just how important the symbolic ritual of shaking hands is upon the way people come to judge others as being trustworthy and willing to cooperate.
"Using a robotic avatar, we were able to demonstrate that this effect holds true even when a person cannot see the face of their counterpart."
The study focused on the impact of handshaking on levels of cooperation and trustworthiness, as well as an individual's willingness to deliberately mislead.
Mock negotiations were set up with 120 people, each involving two participants who were randomly assigned to either the role of buyer or seller, in a fake real-estate scenario.
One person was represented with NAO, allowing researchers to create a system where individuals shook hands prior to negotiations, even though they were in different locations.
The 'virtual' handshake created "connectedness" between both people as they experienced the sensation of grasping a hand or vibration through a controller during the handshake.
Professor Danae Stanton Fraser added: "The formation of interpersonal trust and cooperation are key to future success of computer supported cooperative work, yet the availability of many of the social cues we rely upon when interacting one-to-one are often restricted in these scenarios.
"These findings underline the significance of touch and the simple gesture of a handshake, and will be important as we work to further develop robot systems with valuable applications across society."
In each session of the experiment, one person performed their role through a computer using NAO, which enabled them to see and hear their business partner but not be present in the room.
The person who was present and interacting with NAO could hear the other through the robot's built in speakers but could not see them.
Researchers varied the experiment with negotiations conducted either with no handshake at the beginning, or with handshakes with and without vibration to the remote person.
The robot was used to represent both buyers and sellers, in 60 mock real-estate deals worth between 38m US dollars to 66m US dollars (£24.5m - £42.6m)