Captain Michael Vaughan says England will focus on lifting confidence ahead of the second Test after New Zealand thrashed them by 189 runs in Hamilton.
Pietersen and Vaughan watched disconsolately as England crumbled
England were dismissed for just 110 on day five and Vaughan admits the way they batted is a real concern.
"It's unacceptable the way we played on the last day. The one thing we need to get right is the confidence levels.
"It's pretty clear we're not playing in as confident a fashion as we have in the past and we can do," he explained.
England were criticised for their go-slow approach in the first innings - when they scored at two runs an over - and they were also defensive on the final day at Seddon Park.
They had harboured hopes of victory when Kiwi skipper Daniel Vettori set them 300 after falling to Ryan Sidebottom, who finished with 10 wickets in the match.
But Kyle Mills took 4-7 in his first six overs to rip through the top order and fellow seamer Chris Martin took three wickets on a track that was only expected to help spinners.
The positive thing is we have only three days till the next game
Vaughan says being 1-0 down in the series might bring about a more positive approach from his men when they take the field on Thursday in Wellington.
"To lose in that manner on that pitch we have to ask ourselves questions. We shouldn't be bowled out like that," the skipper admitted.
"We have to put it right over the next few days and try and play with a bit more freedom and confidence.
"In the whole game we were lacking a bit. The positive thing is we have only three days till the next game.
"When you have performances like this you want to get back out on the park and put it right straight away.
"When you lose the first one you know you have to win the next two to win the series and maybe that could be a good thing.
"We can go out and play with natural talent - which a lot of the boys in this team have. We have to make sure we allow the players to express themselves and play in that fashion."
Mills destroyed England's top order with a devastating spell of 4-7
Defeat took England's record to three defeats and four draws in their last seven matches.
Coach Peter Moores, whose tenure began with an easy series win over West Indies, has seen them now lose to India at home, away to Sri Lanka, and struggle at the start in New Zealand.
He maintains his belief has not been shaken despite those setbacks.
"There's always pressure, but I have a vision of how the set-up works along with Michael Vaughan and Paul Collingwood, the one-day captain," he said.
"When I came into the job I didn't think it was going to be easy. It's always a journey and we'll be working hard to get ourselves back on track in this series.
"We all feel we've let some people down. We wanted to play better, we are bitterly disappointed and we have two Tests to put that right and win a series here.
"These players have played well before and we have to be tight as a team. Often through adversity is when you pull together and see what characters are made of."
Both would have been disappointed at how they've performed but I think they had enough time to get themselves ready
Peter Moores on Steve Harmison and Matthew Hoggard
Pacemen Steve Harmison - who delayed his arrival in New Zealand to be present for the birth of his fourth child - and Matthew Hoggard came in for criticism for their performances.
Some critics suggested the duo were rusty but Moores said: "We brought the lads out earlier than we've ever done before. We had a lot of time to prepare.
"It was slightly disrupted for Steve because of the baby and both would have been disappointed at how they've performed but I think they had enough time to get themselves ready. "
New Zealand's players were understandably jubilant after pulling off only their eighth win over England in 89 Tests.
Vettori commented: "We dominated throughout, even though the performance of Ryan Sidebottom lifted England spirits.
"The way we reacted this morning, Kyle Mills and Chris Martin with the ball, set up the victory for us.
"It's been a team performance, guys stepped up at important occasions.
"A lot of good things have come from the Test match. We haven't played that well in Test cricket in recent times but it all came together in the last five days."