Group work in college is related to Johnathan Haidts article about marble sharing. Haidt states that that the "share the spoils" button in humans brains is not pressed by the mere existence of inequality, but when 2 or more people collaborated to produce a gain. In the scenarios where the children would either find the marbles in the cups or be pulling on different ropes to get the marbles out of the machine- they would not end up sharing their wealth between them as they viewed it as 'finders keepers'. Michael Tomasello, a psychologist who created this experiment, believes that the 'share the spoils' response emerged at some point in the last half-million years as humans began to hunt cooperatively. The main key is that if the humans could develop stable, ongoing partnerships they would be able to accomplish much more as a team than if they were alone. So essentially these early humans were responding to the incentive that if they were willing to do work for someone else (and other persons reciprocate) that they will all be better off for it. This can be applied to group work in college if you can put an expectation/ incentivize them to have to work together or else it will negatively impact their own personal grade.
I think this is best accomplished by having two separate grading scales when it comes to group work: an individual grade and a group grade that both go in to calculating the final assignment grade. Group work that only assess participation points or just has a singular completion grade and doesn't assess who did what are much less effective, especially if the professor assigns the groups themselves. Half of the group members are probably incentivized by not wanting to have their grade suffer at the expense of two lazy students and are willing just to do the whole assignment. The two lazy members in this scenario are more than willing to allow these other two students to do the whole assignment in discussion section especially since the hard working students are stuck with the lazy ones because the teacher randomly assigned them. Since there is only one grade that applies to all members regardless of who contributed what, it is more likely than people will be doing uneven amounts of work to receive the same grade.
To remedy this, or to achieve a 'share the spoils' scenario and incentivize members to share wealth (work) evenly, like I stated earlier making two separate grading scales is a good move in my experience. An example of this that I have personally experienced was when I was in a political science course and my group and I had to present on Obamacare. The professor split us into groups but said we are welcome to divvy up responsibility for each part of the project between ourselves as we saw fit. Also he said that 60% of the assignment grade was determined by your own contribution and how well you individually presented and 40% of it was determined by the groups overall presentation. This made it so that if you were with even two sub par group members, that your overall grade could still be high if you did your part well. However, this system incentivized all members to actually want to contribute as the expectation of your grade riding on other peoples work and vice versa makes it so everyone wants to do well by everyone else. We split the project up into 4 parts: background of the bill (what it is trying to do), conservative stance, liberal stance, and actual implementation/ cost it will have. Luckily I was in a rational group and they all worked very hard on their individual parts as did I, and we all just dropped our own individual contributions into a google powerpoint doc without ever meeting up. We all just practiced our parts and expected the other members to show up having done the same since a good proportion of our grades was in eachothers hands. We all received very good grades on the project because we were incentivized to want to share the work as equally as possible and that everyone tried very hard on their part because there was an expectation that others would do the same for your benefit just as much as theirs.