The forms we prefer
Even though humans have evolved over 100 of thousands of years into very sophisticated beings we still have some of those pre-historical reflexes in us left. One of them is our preference of rounded, contoured objects over sharp angled or pointed objects. This is because angular and pointy features activates the amygdala, the region of the brain that is involved in fear processing (likely a mechanism that reacts to potential threats). In addition pointed featured objects have a stronger and deeper level of processing involved than contoured objects, making them, in effect more interesting to look at and an effective means of getting attention. Contoured objects however, make a more positive emotional and aesthetic impression.
The fact that we have a tendency to like contoured objects might be related to our predisposition to perceive certain forms and patterns as human like. Resembling the human face or body is an effective means of getting attention and establishing a positive affective tone for interactions. But strangely enough we favour abstract over (too) realistic anthropomorphic forms.
This effect to see faces has been recognized by the Swiss designers François and Jean Robert, who have a whole collection of photographs and objects in which you can discover a face when you observe them long enough. Somehow, each objects has a pleasant appeal and a kind of ‘ahhh’ moment pops up.