Dier given armband for Brazil clash
The Tottenham midfielder led the Three Lions out for the first time on Friday in the goalless draw with world champions Germany at the 'Home of Football'.
Southgate has decided against naming a permanent captain since he took charge of the national team last year, with a preference for choosing a group of leaders within his squad.
Joe Hart, Gary Cahill, Jordan Henderson and Harry Kane have all donned the armband during the current manager's reign, with Dier the latest to be given the honour.
"It's good experience for him," said Southgate. "I think being the captain on the pitch is one element of being a captain and showing leadership the rest of the time we're in camp is another part.
"The on-field part might help to raise the level of your performance, the level of ownership and responsibility.
"The bigger picture is we want some of these young lads to feel the responsibility a bit more. Eric has good tactical understanding on the field."
The 47-year-old believes that knowledge stems from Dier's formative years at Sporting CP, having returned to the country of his birth in 2014.
"He is a good sounding board for me as a coach when you want to have discussions around tactical problems on the pitch," Southgate added.
"I like to throw that to the players sometimes, just to see what their thinking is. We have our solutions but, if they don't 100 per cent believe in that, some times it is good to listen to what they are thinking.
"He's somebody whose upbringing at Lisbon was slightly different to some young players, they were asked [at Sporting] to make decisions on the field a lot more."