People attach greater value to things they have made themselves than if the very same product was produced by someone else. This cognitive bias is known as the IKEA effect.
Creating something yourself boosts people’s feelings of pride and competence, and has the added effect of showing off their competence to others. This can lead to an overly subjective view of a project.
Chandler: [Rips his jacket on the large wooden tv unit.] Wow! That ripped! That ripped real nice!
Joey: How many times I have to tell you! You, turn and slide! You know, turn and slide.
Chandler: Oh you don’t turn and slide, you throw it out! I’m tired of having to get a tetanus shot every time I get dressed!
Joey: Well, we’re not throwing it out! I built this thing with my own hands! – Friends (1997) Season 4, Episode 2; “The One with the Cat” [No. 75]
‘Virtually all of humans’ highest cognitive achievements are not the work of individuals acting alone but rather of individuals collaborating in groups. Other great apes, especially chimpanzees, coordinate their actions with others in a number of complex ways—for example, in capturing small animals and in coalitions and alliances in intragroup conflicts (Muller & Mitani, 2005). But humans collaborate and communicate with one another in especially complex ways that go beyond simple coordination, ending up with such things as complex social institutions structured by joint goals, division of labor, and communicative symbols.
The ability to collaborate and communicate with others in sophisticated, species-unique ways is apparent even in prelinguistic human infants […]. In a recent comparative study, human 1-year-olds and juvenile chimpanzees each engaged in a collaborative task with a human adult. When the adult stopped participating, the chimpanzees simply tried to solve the task alone. The human children, in contrast, employed various forms of communication to try to reengage the adult into the task. The children seemed to understand that the two of them had committed themselves to doing this together and it simply would not do if the adult was shirking her duty. The collaboration was structured by joint goals and joint commitments to one another (Warneken, Chen, & Tomasello, 2006). It is not difficult to see in these simple activities the roots of the kind of collaborative commitments and activities that structure human social institutions, from governments to religions.’
– Tomasello. M., Herrmann. E. (2010) “Ape and Human Cognition: What’s the difference?” Current Directions in Psychological Science 19(1) 3-8