Boro looked to be cruising at 3-1, but contrived to concede three times to lose 4-3 to further dent their recent recovery under manager Tony Mowbray.
Robson told the club's official website: "It was pretty schoolboy stuff from us, to be honest.
"The goals lost weren't so much about what they [Swansea] did, but mistakes from us.
"When you make stupid mistakes the way we did as a team, that's what happens.
"The way we played in the last 20 minutes was diabolical. When you are 3-1 up at home, you should be killing the game off."
Source: PA
Source: PA