Coach Eddie Jones says England must end their habit of letting leads slip if they want to win the World Cup.
England were 31-0 up on Scotland in Saturday's final Six Nations match, only to be reeled in and eventually draw the game 38-38 at Twickenham.
"It is a recurring thing. It is not a one off," Jones told BBC Radio 5 Live.
"When you want to be the best side in the world you have to put sides like Scotland away. We had the opportunity to do it and we didn't."
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Jones cited both matches as evidence of his side's weakness in converting winning positions to victories.
"We just lacked discipline to keep doing the simple things well," he added.
"We failed to get control and discipline back into the game when it gets loose, and we think we are on top and get a bit 'free-wheely'.
"It's 100% mental - there was no physical difference. It's going to take some digging deep into the team psyche.
"Obviously I am concerned but the great thing is we know the problem and can fix it. It will take time to fix it. We have time to do that, 100%."
England play Wales at home and away on 11 August and 17 August before completing their World Cup warm-up with Tests against Ireland and Italy on 24 August and 6 September.
Their Japan 2019 campaign begins against Tonga two weeks later, with games against the United States, Argentina and France completing their pool fixtures.
Should they qualify for the last eight, Wales and Australia would be their likeliest knock-out opponents, according to world rankings.
Jones believes any repeat of their second-half capitulation could prove costly in Japan.
"You do that in the pool game against Tonga, for instance, then you can find yourselves in a difficult situation going forward," he added.
"So we'd rather have those lessons now and we'll do everything we can to learn from them and make sure it doesn't happen again."
Farrell admits faults
England fly-half Owen Farrell was culpable for two of Scotland's six tries, having a kick charged down by Stuart McInally before Finn Russell intercepted his pass for another break-away score.
"It shocked us when they got a bit of momentum and we gave that to them, me more than anyone at times," he admitted to ITV Sport.
"We got in a rut and couldn't get out of it. That is in our control more than we thought it was, and that is what we have got to get better at.
"They played some good rugby when they got some momentum. They punished us. The disappointing thing is we fed that."
Speaking on BBC Radio 5 live's Sportsweek, Jones said he replaced Farrell with George Ford in the second half because he had "lost his edge".
"Farrell was was a little bit off his best and George has been in exceptional form this week," Jones said.
"We ended up getting the result of a draw due to George's brilliant play."