In the section entitled “the opportunity of defeat,” dweck presents her first reason, which is that students with a growth mind-set show more persistence when faced with obstacles. what evidence does she use to support her view that “attributing poor performance to a lack of ability depresses motivation more than does the belief that lack of effort is to blame?

Carol Dweck is a world-renowned psychologist best known for her book MindSet (2006). Dweck's fields of specialization in psychology are: mindset, success, achievement and motivation.

According to Dweck, "attributing poor performance to a lack of ability depresses motivation more than the belief that lack of effort is to blame". In other words, when an individual belies that (s)he lacks the ability to achieve a task, his/her performance suffers more compared to when s/he believes that lack of effort is the cause of poor performance.

The evidence Dweck provided for this claim was a study conducted at Yale University (1960), where the results indicated that when monkeys were unable to finish a challenge successfully, they attributed their failure to lack of belief in their abilities and perceived that task as beyond their control. As a result, these monkeys simply gave up on the task. In this way, "attributing poor performance to a lack of ability depresses motivation...".

which speech are you talking about?