Known as contour bias (see this page from the book Universal
Principles of Design), rounded corners make objects appear less
harsh and more friendly. The book cites the seminal work on
contour bias as being this article Humans Prefer Curved Visual
Objects by Moshe Bar and Maital Net However, note that rounded
corners are not necessarily the right answer - the book also
says: Objects with pointed features, elicited stronger
activations in the region of the brain related to associative
processing, meaning that although angular objects were less
liked they elicited a deeper level of processing than did the
contoured objects - they were in effect, more interesting and
more thought-provoking to look at So perhaps it is a question of
whether you wish content to appear more friendly or more
noticeable. As the book continues: Angular objects are more
effective at attracting attention and engaging thought;
contoured objects are more effective at making a positive
emotional and aesthetic impression. I was thinking abou