Reporter's notebook: Reexamining the Swiss cheese model

Renowned psychology professor James Reason, who popularized what is known as the Swiss cheese model, has died. Mistakes, Reason theorized, were really a series of vulnerabilities lining up, like a single hole might in a stack of individual slices of Swiss cheese. John Dickerson explains.

Reporter's notebook: Reexamining the Swiss cheese model
Renowned psychology professor James Reason, who popularized what is known as the Swiss cheese model, has died. Mistakes, Reason theorized, were really a series of vulnerabilities lining up, like a single hole might in a stack of individual slices of Swiss cheese. John Dickerson explains.