Karanka questioned the attitude of his players after watching them slide to their third consecutive top-flight defeat.
He said: "It's frustrating for me to work for seven days to try to show them how Tottenham play and how good they are if we let them play, then we go on the pitch and seven minutes later we are losing 1-0.
"These mistakes were made last week and the week before, but the worst and most frustrating thing for me was the attitude, especially in the first half because in the second half we were completely different."
Karanka added: "It's not about ability because we knew Everton have more quality players than us and Tottenham have more quality players than us. It is about convincing them that they are good players.
"It's true we have lost three games in a row but the players know the problem. I was really pleased with the squad after the West Brom game and after three defeats I am really pleased with the squad.
"We have one week now to decide which type of team we are - if we want to be the first half team we will have problems, but if we decide to be the team who played in the second half we will win games so it is in our hands."