Table 1.

Characteristics of the Iowa Gambling Task.

	Deck A	Deck B	Deck C	Deck D
Gain per draw	100	100	50	50
Batch of possible losses per draw	{0,0,0,0,0,150,200,250,300,350}	{0,0,0,0,0,0,0,0,0,1250}	{0,0,0,0,0,0,0,0,0,55,55,55,55,55}	{0,0,0,0,0,0,0,0,0,250}
Range of net loss versus gain per draw	−250 to +100	−1150 to +100	−5 to +50	−200 to +50
Probability of positive net gain per draw	0.5	0.9	0.5	0.9

Each time a card is drawn from one of the decks, the associated gain is won but counterbalanced by a potential loss that is selected at random from the respective batch of losses. The net amount per draw results from subtracting the loss from the gain. Furthermore, achieving a positive net gain only occurs at a certain probability.