The more you clarify your position and defend it against attack, the more committed you become to it. The more you try to convince the other side of the impossibility of changing your opening position, the more difficult it becomes to do so. Your ego becomes identified with your position.
To involve the other side, get them involved early. Ask their advice. Giving credit generously for ideas
Physically sitting side by side can reinforce the mental attitude of tackling a common problem together.
Different values placed on time? You may care more about the present while the other side cares more about the future. In the language of business, you discount future value at different rates. An installment plan works on this principle. The buyer is willing to pay a higher price for the car if he can pay later; the seller is willing to accept payment later if he gets a higher price. Different forecasts? In a salary negotiation between an aging baseball star and a major league baseball team, the player may expect to win a lot of games while the team owner has the opposite expectation. Taking...