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loss schedule matter?
Cognitive Development 24 (2009) 183–191
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Cognitive Development
Young children’s affective decision-making in a gambling task: Does difficulty in learning the gain/loss schedule matter? Shan Gao a,b,c, Yonggang Wei d, Junjie Bai e, Chongde Lin f, Hong Li a,b,∗ a
Key Laboratory of Cognition and Personality (SWU), Ministry of Education, China School of Psychology, Southwest University, China School of Foreign Languages, University of Electronic Science and Technology, China d School of Early Childhood Education, Chongqing Normal University, China e School of Management, Chongqing Technology and Business University, China f School of Psychology, Beijing Normal University, China b c
a r t i c l e
i n f o
Keywords: Affective decision-making (ADM) Children’s Gambling Task (CGT) Gain/loss schedule Loss frequency and magnitude
a b s t r a c t This research investigated the development of affective decisionmaking (ADM) during early childhood, in particular role of difficulty in learning a gain/loss schedule. In Experiment 1, we administrated the Children’s Gambling Task (CGT) to 60 Chinese children aged 3 and 4, replicating the results obtained by Kerr and Zelazo [Kerr, A., & Zelazo, P. D. (2004). Development of “hot” executive function: The Children’s Gambling Task. Brain and Cognition, 55, 148–157]. In Experiment 2, the CGT was modified to make it easier for young children to learn the gain/loss schedule by increasing delayed loss frequency and magnitude in the disadvantageous deck, and a larger sample (181 children aged 3–5) was assessed. Age-differences between 3- and 4-year-olds, rather than 4- and 5-year-olds, showed that ADM develops rapidly between 3 and 4 years. The reduction of the difficulty in learning the gain/loss schedule provides the basis for an account of the development of young children’s AMD. © 2008 Elsevier Inc. All rights reserved.
1. Introduction Affective decision making (ADM) in early childhood deserves more exploration by developmental psychologists, given the recent efforts to understand adult ADM and its necessary neural substrate, ∗ Corresponding author at: School of Psychology, Southwest University, 1 Tiansheng Road, Beibei, Chongqing 400715, China. Tel.: +86 23 68254337; fax: +86 23 68252309. E-mail address: [email protected] (H. Li). 0885-2014/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.cogdev.2008.07.006
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specifically involving the ventromedial prefrontal and orbitofrontal cortex (Bechara, 2004; Bechara, Damasio, Tranel, & Damasio, 1997; Bechara, Tranel, & Damasio, 2000; Bechara, Damasio, Tranel, & Damasio, 2005; Bowman & Turnbull, 2003, 2004; Bowman, Evans, & Turnbull, 2005; Dunn, Dalgleish, & Lawrence, 2006; Kovalchik & Allman, 2006; Krawczyk, 2002; Rolls, 2000, 2004; Turnbull, Berry, & Bowman, 2003; Turnbull, Evans, Bunce, Carzolio, & O’Connor, 2005). Among the behavioral paradigms used to assess decision making involving emotional significance of stimuli or consequences (i.e., meaningful rewards and/or penalties), the Iowa Gambling Task (IGT; Bechara, Damasio, Damasio, & Anderson, 1994) is one of the most widely used. Participants are required to win as much money as possible, across 100 trials, by choosing among four decks of cards (one card per trial). Two decks (advantageous) carry small instant reward and small delayed punishment each trial, and lead to a net win across trials. The other two decks (disadvantageous) carry large instant reward and large delayed punishment, leading to a net loss. Traditionally, this IGT has been given almost exclusively to adults. A few recent studies have modified the IGT for school-aged children and adolescents. These indicate that younger children (e.g., 7–12 years old, Crone & van der Molen, 2004; Crone, Bunge, Latenstein, & van der Molen, 2005; 9–10 years old, Hooper, Lucianaa, Conklina, & Yargera, 2004) have difficulty making advantageous choices on those tasks. However, it is unclear whether these variant IGT tasks are appropriate for the investigation of ADM in children. In the first attempts to administer the IGT to young children, researchers simplified the task. For example, Kerr and Zelazo (2004) created the Children’s Gambling Task (CGT), designed to be sensitive to age-related changes in ADM between 3 and 4 years. Children selected a card from either of two decks for 50 trials. One deck offered higher immediate gains (i.e., candies) each trial, but was disadvantageous overall due to occasional large losses. The other offered lower immediate gains each trial but was advantageous in the long run. Results revealed a significant performance difference between 3- and 4year-olds. Using another child version of the IGT, without any specific learning schedule or instruction to the participants, Garon and Moore (2004) failed to find significant age effects for overall performance among 3-, 4- and 6-year-olds. They argued that lack of an age effect might be due to the small number of trials (40). Research on decision-making tasks involving multiple trials have suggested that it takes many trials for learning and performance differences to emerge in adults (Busemeyer & Myung, 1992; Kleinmuntz & Thomas, 1987; Tranel, Bechara, & Damasio, 2000). Hence, with trials, a larger difference may have emerged across age groups. Further, Garon and Moore’s task is more complex than the CGT. Like the adult version of the IGT, it involves four decks of cards (i.e., advantageous/frequent loss, disadvantageous/frequent loss, advantageous/infrequent loss, and disadvantageous/infrequent loss). If there were fewer decks and therefore fewer reward contingencies to learn, it may have taken fewer trials for children to learn those contingencies, making it possible to detect age differences in learning. Compared with this modification of the IGT, the CGT is a more sensitive and effective measure of the development of ADM in early childhood. This conclusion is supported by a later study by Garon and Moore (2007), in which only two decks were used and age-related improvement was found between 3.5- and 4.5-year-olds. As an alternative version of the IGT, the CGT also entails several component functions whose development may contribute to age differences in AMD, such as the ability to inhibit and reverse previous learning of stimuli contingencies (Overman, Bachevalier, Schuhmann, & Ryan, 1996). In the present work, we wish to emphasize on the ability to learn the gain/loss schedule, which is crucial to imagining future scenarios and being motivated by the affective properties of those representations, that is, the ability to anticipate future outcomes. Regarding this component function, preschool children are unlikely to be able to perform exact calculations of net gains and losses, since the punishment magnitudes are variable across trials. In such tasks, learning depends largely on approximation or estimation. Estimation plays an important role in children’s arithmetic (Baroody, 1999), which would greatly influence their calculation of net gains and losses. However, children’s estimation ability is still limited, and they need to acquire more strategies to improve their calculation (Lemaire & Lecacheur, 2002). Thus, for the CGT we presume that if the reward schedule is predictable, frequency and magnitude of penalties will eventually have an effect on contingency learning and adaptive responses. This prediction is supported by hemodynamic and electrophysiological data from adult humans and non-human primates, involving prefrontal and basal ganglia regions (Dayan, 2004; Schultz, Dayan, & Montague, 1997), which closely fit temporal-difference models of contingent reinforcement learning
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(Sutton & Barto, 1998). One prediction from these well-supported models is that increasing loss frequency and magnitude in the disadvantageous deck may make it easier to track the reward/punishment contingency and thus distinguish between the “good” deck and the “bad” deck. This is so because increasing the discrepancy between gain and loss in the disadvantageous deck should facilitate representing the disadvantageous deck as more disadvantageous, all else being equal, given that past outcomes in reinforcement learning are systematically “discounted” (for example, averaging, forgetting, or interference from intervening trials (Sutton & Barto, 1998). The aim of the research presented here is to explore the role of difficulty in learning the gain/loss schedule in young children’s ADM. We chose the CGT (Kerr & Zelazo, 2004), as an age-appropriate instrument for examining the development of ADM in early childhood. However, because the present participants were Chinese instead of Canadian as in Kerr and Zelazo (2004) study, we deemed it necessary to first replicate the age-related changes reported in their study before testing a possible explanation for them. In addition, this experiment examined sex differences in order to address inconsistent findings regarding of sex differences in two prior preschool studies of the IGT. Specifically, boys outperformed girls (a non-significant trend) in Kerr and Zelazo (2004), whereas girls outperformed boys in Garon and Moore (2004). 2. Experiment 1 The task employed in Experiment 1, was identical to the original CGT except for the addition of three demonstration trials and a corresponding increase in the number of cards in each deck from 50 to 53. This addition did not affect the gain/loss contingencies, as each child still made 50 choices. The large number of cards avoided the possibility of the cards in any deck running out leaving the child unable to complete enough trials. 2.1. Method 2.1.1. Participants Thirty children at each of two ages, 3 years (M = 42.0 months, range = 36–47 months, S.D. = 3.6) and 4 years (M = 52.6 months, range = 48–59 months, S.D. = 3.5), were randomly recruited from day-care centers in Chongqing, China. Sixteen of the 3-year-olds were boys and 14 of the 4-year-olds were boys. 2.1.2. Materials The task involved 2 decks of cards (20 cm × 30 cm), each containing 53 cards. Three of each were sample cards used in demonstration trials. The back of one deck was covered with black and white vertical stripes, whereas the back of the other deck was covered with black dots on a white background. The front of every card was divided into a white top half and a black bottom half. Black happy faces appeared on the top half of the card, and white sad faces appeared on the bottom half. The number of happy faces on each card indicated the number of rewards (candies) gained, and the number of sad faces indicated the number of rewards lost. Cards in the deck with stripes provided a gain of one reward (i.e., they showed one happy face) and zero or one losses. Consequently, choosing from this deck it was advantageous over trials (with a net average of 5 candies gained per block of 10 cards). Cards in the deck with dots provided a gain of two and losses of 0, 4, 5, or 6 candies. This deck thus was disadvantageous over the long term (with a net average of 7 candies lost per 10 cards). Specifically, the advantageous deck contained 27 cards with 0 losses and 26 cards with 1 loss; the disadvantageous deck contained 25 cards with 0 losses, 10 cards with 4 losses, 8 cards with 5 losses, and 10 cards with 6 losses. During testing, the bottom half of the front side of each card was covered with a foam paper that the experimenter needed to remove in order to reveal any sad faces. This feature of the task was intended to clarify the presentation of information associated with each card, and to force children to attend first to the reward information. Rewards were Qishi fruit candies, which a very familiar and motivating to most Chinese children. When children gained rewards, candies were drawn from a box and put into a glass. When children lost rewards, candies were removed from the glass and returned to the box.
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2.1.3. Procedure The experiment included of 6 demonstration trials (3 from each deck) and 50 test trials. Only test trial responses were included in data analysis. Each child was tested individually by a female experimenter in a single session lasting approximately 25 min. Once the child was comfortable with the situation and the experimenter, he or she was seated at a small table. The two decks of cards were then placed face down in front of the child (separated by about 20 cm), and the reward glass was placed between the decks. The experimenter sat beside the child and kept the candy box in front of her. The left right positioning of the decks was determined randomly for each child. The child was given one candy to eat and asked whether he or she wanted to win more candies. He or she was then introduced to the task. The child was told, “Okay, in this game we’ll put the candies that you win in this tub here. I’m going to give you 10 to play the game, and I’ll show you how the game works and how you can win some more.” Ten candies were counted out and deposited into the glass. The experimenter then demonstrated how the task worked by selecting three cards consecutively from each deck, starting with the advantageous deck. On each demonstration trial, the experimenter explained, “Look, there are 2 happy faces. That means you win 2 candies.” Two candies were then taken from the box, placed demonstratively on top of the two happy faces to illustrate the one-to-one correspondence between number of faces and number of rewards gained, and then added to the glass. The experimenter then proceeded to check for losses, pointing to the foam paper covering the bottom half of the card and saying, “Well, now we have to open this up. Oh look, there are 5 sad faces. That means you lose 5 candies so we have to give 5 back.” The experimenter then removed 5 candies from the glass, placed them on top of the five sad faces, and then deposited them in the box. At the end of the demonstration, the experimenter said, “We don’t like the sad faces, do we? Because they make us lose candies. But we like the happy faces, right? Because we can win candies!” This procedure was repeated for all of the demonstration trials. Thus, although the child was not told that one of the decks was better than the other, he or she was forced to sample from each deck, and the fixed sequence of gain/loss contingencies ensured that a representative sample was obtained. After the 6 demonstration trials, the experimenter said, “Okay, now we’ll begin to play the game. You may choose whichever card you want to play with every time, from the dots or the stripes. You can choose one every time and pick as many cards as you want until I say STOP, and then the game will be over. So remember, win as many candies as possible! Let’s see if we can fill this tub right up to the top with candies! Whatever you have in the tub at the end of the game, you can eat or take home with you. Ready? Which card do you want to pick first?” Test trials were exactly like the demonstration trials. Every time a card was turned over, the experimenter announced the number of candies won, placed them on the happy faces, and then deposited them in the glass. Then the foam paper was removed, the number of losses was announced, and the corresponding number of candies was removed from the glass, placed on top of the sad faces, and then deposited into the box. The child was not allowed to eat any of the candies until after the last test trial (trial 50), and the child was not told how many test trials there would be. If children made a preponderance of disadvantageous selections, it was possible for them to incur losses that they were unable to pay. When this happened, children were told, “We don’t even have that many to give back, so we’ll just have to take everything back and play again.” 2.2. Results and discussion The primary dependent measure was whether children made an advantageous or a disadvantageous choice on each trial. All children completed 50 trials. We analyzed data in the same way as Kerr and Zelazo (2004) did. Ten test trials constituted a block, yielding a total of five blocks. Proportion scores were used to analyze performance across blocks. We computed the proportion of advantageous choices per block minus the proportion of disadvantageous choices per block, which yielded difference scores ranging from −1 to 1. In block 1, for example, if a child made 6 advantageous selections and 4 disadvantageous, his or her difference score in the block was, 0.6 − 0.4 = 0.2. Positive difference scores indicated relatively advantageous performance, whereas negative scores indicated relatively disadvantageous performance.
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Fig. 1. Performance of 3- and 4-year-olds across blocks in Experiment 1.
Difference scores were then analyzed using a 2 (age: 3 vs. 4 years) × 2 (sex) × 5 (blocks 1–5) mixed model analysis of variance (ANOVA). This analysis showed no effect of sex but a significant main effect of age, F(1, 56) = 6.657, p < .05, and block, F(4, 224) = 6.093, p < .000. Tests of simple effects indicated that scores increased across blocks for 4-year-olds, F(4, 116) = 4.266, p < .01, but not 3-year-olds, F(4, 116) = 2.179, p > .05 and that 4-year-olds made more advantageous choices than 3-year-olds on blocks 2, F(1, 56) = 4.49, p < .05, 4, F(1, 56) = 4.288, p < .05, and 5, F(1, 56) = 7.244, p < .01. These effects of age and block were very similar to those reported by Kerr and Zelazo (2004). Means (with SEs) are shown in Fig. 1. The t-distribution was used to compare means for each age and block to the mean expected based on random responding (i.e., 0). Three-year-olds’ mean scores were significantly lower than chance (i.e., more disadvantageous) for blocks 2 and 3 (p < .05). Four-year-olds’ means were significantly higher than chance (i.e., more advantageous) for blocks 4 and 5 (p < .01). We also examined the performance of individual children. The binomial theorem was applied to see whether each child made more advantageous or disadvantageous selections across 50 trials than would be expected by chance based on an alpha of .05 (i.e., 31). Among 3-year-olds, 9 children (3 boys and 6 girls) made more disadvantageous choices than would be expected by chance, whereas only 4 children (1 boy and 3 girls) made more advantageous choices. Among 4-year-olds, only 2 children (1 boy and 1 girl) made more disadvantageous choices, whereas 10 children (6 boys and 4 girls) made more advantageous choices. 3. Experiment 2 Three-year-olds in Experiment 1 tended to choose disadvantageously, as did those in Kerr and Zelazo’s (2004) study. We wondered whether their maladaptive choice was attributable to their difficulty in learning the gain/loss schedule, a candidate mechanisms for age differences in AMD. If schedule learning was made easier by increasing punishment frequency and magnitude in the bad deck, would younger perform better? To address this question we developed a variant of the CGT with losses more frequent and larger in the disadvantageous deck. Specifically, the proportion of gain cards was reduced to 31% (originally 48%) whereas cards with 4, 5, or 6 losses were increased to a total of 69% (originally 52%). These changes increased the average discrepancy between the disadvantageous and advantageous deck from 1.07 to 1.42 in the loss proportion. With this manipulation, children should learn more easily the gain/loss schedule and the distinct properties of the two decks. Another goal of Experiment 2 was to assess more across a broader range than that employed by age-related changed in AMD. Notably, Kerr and Zelazo (2004) and Experiment 1. Although both studies show age-related improvement in ADM, 4-year-olds did not show optimal performance. In Experiment 2, therefore, a group of 5-year-olds was added. Doing so will begin to close the gap between studies of
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AMD in preschool children and the more numerous studies of older children (Crone & van der Molen, 2004, 2007; Crone et al., 2005; Garon & Moore, 2004; Hooper et al., 2004; Overman, 2004; Peters & Slovic, 2000; Suhr & Tsanadis, 2007; Turnbull et al., 2005). 3.1. Method 3.1.1. Participants Sixty 3-year-olds (M = 42.6 months, range = 36–47 months, S.D. = 3.1), 61 four-year-olds (M = 54.1 months, range = 48–59 months, S.D. = 3.2), and 60 five-year-olds (M = 67.0 months, range = 60–71 months, S.D. = 3.3), were randomly recruited from day-care centers in Chongqing, China. Thirty of the 3-year-olds were boys and 29 of each of the other two ages groups were boys. None had participated in Experiment 1. 3.1.2. Materials The materials were identical to those in Experiment 1, except the disadvantageous deck was modified to contain 16 cards with 0 losses, 11 cards with 4 losses, 10 cards with 5 losses, and 16 cards with 6 losses; thus 10 choices would yield a net average loss of 16 candies. The sequence of gain/loss contingencies was fixed in a given order different from that in Experiment 1. 3.1.3. Procedure The procedure was the same as in Experiment 1. 3.2. Results and discussion Difference scores were analyzed by ANOVA as in Experiment 1. In comparing 3- and 4-year-olds, there was a significant main effect of age, F(1, 117) = 25.812, p < .0001, and a significant age × block interaction, F(4, 468) = 13.036, p < .000. The difference between 4- and 5-year-olds was not significant, F(1, 117) = 0.037, p > .05, nor was the age × block interaction, F(4, 468) = 0.836, p > .05. Tests of simple effects indicated that scores increased across blocks for 4-year-olds, F(4, 240) = 25.190, p < .0001, and 5-yearolds, F(4, 236) = 26.364, p < .0001, but not 3-year-olds, F(4, 236) = 0.438, p > .05. Four-year-olds made more advantageous choices than 3-year-olds on all the blocks (Fblock1 = 4.842, p < .05; Fblock2 = 7.886, p < .01; Fblock3 = 26.932, p < .000; Fblock4 = 25.799, p < .000; Fblock5 = 30.635, p < .000). In contrast, 4- and 5-year-olds performed similarly in all blocks. These results are illustrated in Fig. 2. We used the binomial theorem to determine whether each child made more advantageous or disadvantageous choices across 50 trials than would be expected by chance based on an alpha of .05 (i.e., 33 or more). Among 3-year-olds, 13 children (6 boys and 7 girls) made more disadvantageous choices
Fig. 2. Performance of children at different ages across blocks in Experiment 2.
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than would be expected by chance, and 10 children (6 boys and 4 girls) made more advantageous choices. Among 4-year-olds, none made more disadvantageous choices, whereas 33 children (19 boys and 14 girls) made more advantageous choices. Similarly, none of the 5-year-olds made more disadvantageous choices, whereas 33 of them (18 boys and 15 girls) made more advantageous choices. A main effect of gender favoring boys approached conventional significance, F(1, 175) = 3.750, p = 0.054, and a significant sex × block interaction appeared, F(4, 700) = 4.161, p < .01. On the last 4 trial blocks there emerged a significant sex difference, F(1, 175) = 5.170, p < .05, and a significant sex × age × block interaction, F(6, 525) = 2.366, p < .05. No significant sex difference emerged at the age of 3, or 5, but a sex difference was significant among 4-year-olds, F(1, 59) = 4.361, p < .05. In sum, the findings of Experiment 2 confirmed those of Experiment 1 as well as the findings of Kerr and Zelazo (2004), indicate that performance on the CGT improves from 3 to 4 years of age. Further, this development does not continue its trajectory into the fifth year. To gain some qualitative insight into younger children’s performance, we collected oral reports from 33 three-year-olds immediately after they finished the task. When asked, “Do you know which deck of cards can help you gain candies”, 18 children responded “yes” and pointed to the advantageous deck. Of the 18 children, 11 did not make more advantageous choices than would be expected by chance and only 7 chose significantly advantageously. Thus, children might not do well in the task even if they have gained some understanding of the contingency structure. This reinforced the notion that contingency learning alone cannot explain satisfactorily the ADM deficit of 3-year-olds. 4. General discussion The present study created a variant of the CGT by presenting delayed punishment in higher frequency and magnitude in the advantageous deck so as to make it easier to learn the gain/loss schedule and appreciate the value of each deck. The purpose was to reduce the potential influence of the ability to learn the gain/loss schedule. In Experiment 1, we examined the development of ADM between 3 and 4 years of age, employing an alternative version of the IGT, the CGT (Kerr & Zelazo, 2004). In Experiment 2, 3- to 5-year-olds were tested on a modification of the CGT. Performance showed significant improvement between 3 and 4 years but not between 4 and 5 years. The two experiments suggest that ADM develops rapidly between 3 and 4 years of age, consistent with previous findings (Garon & Moore, 2007; Kerr & Zelazo, 2004). Our findings suggest that modest differences in the gain/loss discrepancy between the advantageous and disadvantageous decks do not qualitatively influence this pattern. However, the CGT is a complex decision-making task that likely involves several inter-related abilities and demands cognitive–affective integration or interaction. In the task learning process preschoolers can hardly calculate exact net gains and losses under such uncertainty. Comprehension will be based on approximation. Contingency learning may, to some degree, be influenced by working memory or inductive learning variability. However, there is no evidence that memory or inductive learning processes are isolated from affective processes. We do not think that the gain/loss schedule is cognitively impenetrable or that emotion works in the absence of cognitive functions. Such learning may involve cognitive–affective integration or interaction, in which knowledge of the task contingencies, overt or covert, is developed by feeling and/or by reasoning. Thus, different contexts may make one element more important than another. It is unlikely that one function alone is entirely responsible for human decision-making in a complex task like the IGT and the CGT. Therefore, we must further evaluate the extent to which different factors contribute to performance by different age groups. Experiment 2 indicated that the development of ADM may be superior in boys in early childhood, which parallels the sex difference found by Kerr and Zelazo (2004) and by Overman et al. (1996) in infants and toddlers on a simpler measure of OFC function—object reversal. Male advantage in ADM has also been detected in school-aged children and adolescents (Crone et al., 2005; Crone & van der Molen, 2007; Overman et al., 2003) and adults (Bolla, Eldreth, Matochik, & Cadet, 2004; Reavis & Overman, 2001). Using the IGT with a large sample of adolescents, D’Acremont and van der Linden (2006) found a clear female advantage in decision-making, possibly as a result of boys’ more frequent risk-taking behavior. The unexpected female advantage found by Garon and Moore (2004) is probably due to some important differences between their task and some other versions of the IGT (see Garon & Moore, 2004, for a review). Similarly, the sex difference in our second experiment may be attributable
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to either a larger sample or the likelihood that increasing punishment in frequency and magnitude amplified the sex difference. Finally, in addition to the potential mechanisms discussed above, there are still some other factors that may influence children’s performance on the CGT, such as risk-taking (see Dunn et al., 2006, for a review) and personality. The current research revealed notable individual differences in performance within each age group. At each age, some children made a majority of advantageous choices, while others made a majority of disadvantageous choices. There is evidence that adult performance on a variant of the IGT is associated with self-report measures of personality (Peters & Slovic, 2000). Individuals rated in negative affectivity tended to avoid high losses, and individuals high in positive affectivity tended to seek high gains. Suhr and Tsanadis (2007) demonstrated that personality (funseeking) was correlated with adult performance on the IGT. Davis, Pattea, Tweed, and Curtis (2007) detected some relations between adult performance on a version of the IGT and personality traits such as impulsivity and addiction. In the present study, some children did show obvious risk-taking behavior. Nevertheless, Franken and Muris (2005) reported that behavioral decision-making was not predicted by impulsive personality traits. Risk-taking was found not significantly correlated with performance on the IGT (Overman, 2004). In brief, accounts of the relation between individual personality and IGT performance are controversial. The issue of personality seems as intriguing as sex differences on the IGT and the CGT. Yet these questions, and more precise decomposition of the complex decision-making involved in the CGT, inspire our future efforts. Acknowledgements We wish to give our sincere thanks to Gedeon O. Deák and Philip D. Zelazo for their helpful suggestions. 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Contents lists available at ScienceDirect
Cognitive Development
Young children’s affective decision-making in a gambling task: Does difficulty in learning the gain/loss schedule matter? Shan Gao a,b,c, Yonggang Wei d, Junjie Bai e, Chongde Lin f, Hong Li a,b,∗ a
Key Laboratory of Cognition and Personality (SWU), Ministry of Education, China School of Psychology, Southwest University, China School of Foreign Languages, University of Electronic Science and Technology, China d School of Early Childhood Education, Chongqing Normal University, China e School of Management, Chongqing Technology and Business University, China f School of Psychology, Beijing Normal University, China b c
a r t i c l e
i n f o
Keywords: Affective decision-making (ADM) Children’s Gambling Task (CGT) Gain/loss schedule Loss frequency and magnitude
a b s t r a c t This research investigated the development of affective decisionmaking (ADM) during early childhood, in particular role of difficulty in learning a gain/loss schedule. In Experiment 1, we administrated the Children’s Gambling Task (CGT) to 60 Chinese children aged 3 and 4, replicating the results obtained by Kerr and Zelazo [Kerr, A., & Zelazo, P. D. (2004). Development of “hot” executive function: The Children’s Gambling Task. Brain and Cognition, 55, 148–157]. In Experiment 2, the CGT was modified to make it easier for young children to learn the gain/loss schedule by increasing delayed loss frequency and magnitude in the disadvantageous deck, and a larger sample (181 children aged 3–5) was assessed. Age-differences between 3- and 4-year-olds, rather than 4- and 5-year-olds, showed that ADM develops rapidly between 3 and 4 years. The reduction of the difficulty in learning the gain/loss schedule provides the basis for an account of the development of young children’s AMD. © 2008 Elsevier Inc. All rights reserved.
1. Introduction Affective decision making (ADM) in early childhood deserves more exploration by developmental psychologists, given the recent efforts to understand adult ADM and its necessary neural substrate, ∗ Corresponding author at: School of Psychology, Southwest University, 1 Tiansheng Road, Beibei, Chongqing 400715, China. Tel.: +86 23 68254337; fax: +86 23 68252309. E-mail address: [email protected] (H. Li). 0885-2014/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.cogdev.2008.07.006
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specifically involving the ventromedial prefrontal and orbitofrontal cortex (Bechara, 2004; Bechara, Damasio, Tranel, & Damasio, 1997; Bechara, Tranel, & Damasio, 2000; Bechara, Damasio, Tranel, & Damasio, 2005; Bowman & Turnbull, 2003, 2004; Bowman, Evans, & Turnbull, 2005; Dunn, Dalgleish, & Lawrence, 2006; Kovalchik & Allman, 2006; Krawczyk, 2002; Rolls, 2000, 2004; Turnbull, Berry, & Bowman, 2003; Turnbull, Evans, Bunce, Carzolio, & O’Connor, 2005). Among the behavioral paradigms used to assess decision making involving emotional significance of stimuli or consequences (i.e., meaningful rewards and/or penalties), the Iowa Gambling Task (IGT; Bechara, Damasio, Damasio, & Anderson, 1994) is one of the most widely used. Participants are required to win as much money as possible, across 100 trials, by choosing among four decks of cards (one card per trial). Two decks (advantageous) carry small instant reward and small delayed punishment each trial, and lead to a net win across trials. The other two decks (disadvantageous) carry large instant reward and large delayed punishment, leading to a net loss. Traditionally, this IGT has been given almost exclusively to adults. A few recent studies have modified the IGT for school-aged children and adolescents. These indicate that younger children (e.g., 7–12 years old, Crone & van der Molen, 2004; Crone, Bunge, Latenstein, & van der Molen, 2005; 9–10 years old, Hooper, Lucianaa, Conklina, & Yargera, 2004) have difficulty making advantageous choices on those tasks. However, it is unclear whether these variant IGT tasks are appropriate for the investigation of ADM in children. In the first attempts to administer the IGT to young children, researchers simplified the task. For example, Kerr and Zelazo (2004) created the Children’s Gambling Task (CGT), designed to be sensitive to age-related changes in ADM between 3 and 4 years. Children selected a card from either of two decks for 50 trials. One deck offered higher immediate gains (i.e., candies) each trial, but was disadvantageous overall due to occasional large losses. The other offered lower immediate gains each trial but was advantageous in the long run. Results revealed a significant performance difference between 3- and 4year-olds. Using another child version of the IGT, without any specific learning schedule or instruction to the participants, Garon and Moore (2004) failed to find significant age effects for overall performance among 3-, 4- and 6-year-olds. They argued that lack of an age effect might be due to the small number of trials (40). Research on decision-making tasks involving multiple trials have suggested that it takes many trials for learning and performance differences to emerge in adults (Busemeyer & Myung, 1992; Kleinmuntz & Thomas, 1987; Tranel, Bechara, & Damasio, 2000). Hence, with trials, a larger difference may have emerged across age groups. Further, Garon and Moore’s task is more complex than the CGT. Like the adult version of the IGT, it involves four decks of cards (i.e., advantageous/frequent loss, disadvantageous/frequent loss, advantageous/infrequent loss, and disadvantageous/infrequent loss). If there were fewer decks and therefore fewer reward contingencies to learn, it may have taken fewer trials for children to learn those contingencies, making it possible to detect age differences in learning. Compared with this modification of the IGT, the CGT is a more sensitive and effective measure of the development of ADM in early childhood. This conclusion is supported by a later study by Garon and Moore (2007), in which only two decks were used and age-related improvement was found between 3.5- and 4.5-year-olds. As an alternative version of the IGT, the CGT also entails several component functions whose development may contribute to age differences in AMD, such as the ability to inhibit and reverse previous learning of stimuli contingencies (Overman, Bachevalier, Schuhmann, & Ryan, 1996). In the present work, we wish to emphasize on the ability to learn the gain/loss schedule, which is crucial to imagining future scenarios and being motivated by the affective properties of those representations, that is, the ability to anticipate future outcomes. Regarding this component function, preschool children are unlikely to be able to perform exact calculations of net gains and losses, since the punishment magnitudes are variable across trials. In such tasks, learning depends largely on approximation or estimation. Estimation plays an important role in children’s arithmetic (Baroody, 1999), which would greatly influence their calculation of net gains and losses. However, children’s estimation ability is still limited, and they need to acquire more strategies to improve their calculation (Lemaire & Lecacheur, 2002). Thus, for the CGT we presume that if the reward schedule is predictable, frequency and magnitude of penalties will eventually have an effect on contingency learning and adaptive responses. This prediction is supported by hemodynamic and electrophysiological data from adult humans and non-human primates, involving prefrontal and basal ganglia regions (Dayan, 2004; Schultz, Dayan, & Montague, 1997), which closely fit temporal-difference models of contingent reinforcement learning
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(Sutton & Barto, 1998). One prediction from these well-supported models is that increasing loss frequency and magnitude in the disadvantageous deck may make it easier to track the reward/punishment contingency and thus distinguish between the “good” deck and the “bad” deck. This is so because increasing the discrepancy between gain and loss in the disadvantageous deck should facilitate representing the disadvantageous deck as more disadvantageous, all else being equal, given that past outcomes in reinforcement learning are systematically “discounted” (for example, averaging, forgetting, or interference from intervening trials (Sutton & Barto, 1998). The aim of the research presented here is to explore the role of difficulty in learning the gain/loss schedule in young children’s ADM. We chose the CGT (Kerr & Zelazo, 2004), as an age-appropriate instrument for examining the development of ADM in early childhood. However, because the present participants were Chinese instead of Canadian as in Kerr and Zelazo (2004) study, we deemed it necessary to first replicate the age-related changes reported in their study before testing a possible explanation for them. In addition, this experiment examined sex differences in order to address inconsistent findings regarding of sex differences in two prior preschool studies of the IGT. Specifically, boys outperformed girls (a non-significant trend) in Kerr and Zelazo (2004), whereas girls outperformed boys in Garon and Moore (2004). 2. Experiment 1 The task employed in Experiment 1, was identical to the original CGT except for the addition of three demonstration trials and a corresponding increase in the number of cards in each deck from 50 to 53. This addition did not affect the gain/loss contingencies, as each child still made 50 choices. The large number of cards avoided the possibility of the cards in any deck running out leaving the child unable to complete enough trials. 2.1. Method 2.1.1. Participants Thirty children at each of two ages, 3 years (M = 42.0 months, range = 36–47 months, S.D. = 3.6) and 4 years (M = 52.6 months, range = 48–59 months, S.D. = 3.5), were randomly recruited from day-care centers in Chongqing, China. Sixteen of the 3-year-olds were boys and 14 of the 4-year-olds were boys. 2.1.2. Materials The task involved 2 decks of cards (20 cm × 30 cm), each containing 53 cards. Three of each were sample cards used in demonstration trials. The back of one deck was covered with black and white vertical stripes, whereas the back of the other deck was covered with black dots on a white background. The front of every card was divided into a white top half and a black bottom half. Black happy faces appeared on the top half of the card, and white sad faces appeared on the bottom half. The number of happy faces on each card indicated the number of rewards (candies) gained, and the number of sad faces indicated the number of rewards lost. Cards in the deck with stripes provided a gain of one reward (i.e., they showed one happy face) and zero or one losses. Consequently, choosing from this deck it was advantageous over trials (with a net average of 5 candies gained per block of 10 cards). Cards in the deck with dots provided a gain of two and losses of 0, 4, 5, or 6 candies. This deck thus was disadvantageous over the long term (with a net average of 7 candies lost per 10 cards). Specifically, the advantageous deck contained 27 cards with 0 losses and 26 cards with 1 loss; the disadvantageous deck contained 25 cards with 0 losses, 10 cards with 4 losses, 8 cards with 5 losses, and 10 cards with 6 losses. During testing, the bottom half of the front side of each card was covered with a foam paper that the experimenter needed to remove in order to reveal any sad faces. This feature of the task was intended to clarify the presentation of information associated with each card, and to force children to attend first to the reward information. Rewards were Qishi fruit candies, which a very familiar and motivating to most Chinese children. When children gained rewards, candies were drawn from a box and put into a glass. When children lost rewards, candies were removed from the glass and returned to the box.
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2.1.3. Procedure The experiment included of 6 demonstration trials (3 from each deck) and 50 test trials. Only test trial responses were included in data analysis. Each child was tested individually by a female experimenter in a single session lasting approximately 25 min. Once the child was comfortable with the situation and the experimenter, he or she was seated at a small table. The two decks of cards were then placed face down in front of the child (separated by about 20 cm), and the reward glass was placed between the decks. The experimenter sat beside the child and kept the candy box in front of her. The left right positioning of the decks was determined randomly for each child. The child was given one candy to eat and asked whether he or she wanted to win more candies. He or she was then introduced to the task. The child was told, “Okay, in this game we’ll put the candies that you win in this tub here. I’m going to give you 10 to play the game, and I’ll show you how the game works and how you can win some more.” Ten candies were counted out and deposited into the glass. The experimenter then demonstrated how the task worked by selecting three cards consecutively from each deck, starting with the advantageous deck. On each demonstration trial, the experimenter explained, “Look, there are 2 happy faces. That means you win 2 candies.” Two candies were then taken from the box, placed demonstratively on top of the two happy faces to illustrate the one-to-one correspondence between number of faces and number of rewards gained, and then added to the glass. The experimenter then proceeded to check for losses, pointing to the foam paper covering the bottom half of the card and saying, “Well, now we have to open this up. Oh look, there are 5 sad faces. That means you lose 5 candies so we have to give 5 back.” The experimenter then removed 5 candies from the glass, placed them on top of the five sad faces, and then deposited them in the box. At the end of the demonstration, the experimenter said, “We don’t like the sad faces, do we? Because they make us lose candies. But we like the happy faces, right? Because we can win candies!” This procedure was repeated for all of the demonstration trials. Thus, although the child was not told that one of the decks was better than the other, he or she was forced to sample from each deck, and the fixed sequence of gain/loss contingencies ensured that a representative sample was obtained. After the 6 demonstration trials, the experimenter said, “Okay, now we’ll begin to play the game. You may choose whichever card you want to play with every time, from the dots or the stripes. You can choose one every time and pick as many cards as you want until I say STOP, and then the game will be over. So remember, win as many candies as possible! Let’s see if we can fill this tub right up to the top with candies! Whatever you have in the tub at the end of the game, you can eat or take home with you. Ready? Which card do you want to pick first?” Test trials were exactly like the demonstration trials. Every time a card was turned over, the experimenter announced the number of candies won, placed them on the happy faces, and then deposited them in the glass. Then the foam paper was removed, the number of losses was announced, and the corresponding number of candies was removed from the glass, placed on top of the sad faces, and then deposited into the box. The child was not allowed to eat any of the candies until after the last test trial (trial 50), and the child was not told how many test trials there would be. If children made a preponderance of disadvantageous selections, it was possible for them to incur losses that they were unable to pay. When this happened, children were told, “We don’t even have that many to give back, so we’ll just have to take everything back and play again.” 2.2. Results and discussion The primary dependent measure was whether children made an advantageous or a disadvantageous choice on each trial. All children completed 50 trials. We analyzed data in the same way as Kerr and Zelazo (2004) did. Ten test trials constituted a block, yielding a total of five blocks. Proportion scores were used to analyze performance across blocks. We computed the proportion of advantageous choices per block minus the proportion of disadvantageous choices per block, which yielded difference scores ranging from −1 to 1. In block 1, for example, if a child made 6 advantageous selections and 4 disadvantageous, his or her difference score in the block was, 0.6 − 0.4 = 0.2. Positive difference scores indicated relatively advantageous performance, whereas negative scores indicated relatively disadvantageous performance.
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Fig. 1. Performance of 3- and 4-year-olds across blocks in Experiment 1.
Difference scores were then analyzed using a 2 (age: 3 vs. 4 years) × 2 (sex) × 5 (blocks 1–5) mixed model analysis of variance (ANOVA). This analysis showed no effect of sex but a significant main effect of age, F(1, 56) = 6.657, p < .05, and block, F(4, 224) = 6.093, p < .000. Tests of simple effects indicated that scores increased across blocks for 4-year-olds, F(4, 116) = 4.266, p < .01, but not 3-year-olds, F(4, 116) = 2.179, p > .05 and that 4-year-olds made more advantageous choices than 3-year-olds on blocks 2, F(1, 56) = 4.49, p < .05, 4, F(1, 56) = 4.288, p < .05, and 5, F(1, 56) = 7.244, p < .01. These effects of age and block were very similar to those reported by Kerr and Zelazo (2004). Means (with SEs) are shown in Fig. 1. The t-distribution was used to compare means for each age and block to the mean expected based on random responding (i.e., 0). Three-year-olds’ mean scores were significantly lower than chance (i.e., more disadvantageous) for blocks 2 and 3 (p < .05). Four-year-olds’ means were significantly higher than chance (i.e., more advantageous) for blocks 4 and 5 (p < .01). We also examined the performance of individual children. The binomial theorem was applied to see whether each child made more advantageous or disadvantageous selections across 50 trials than would be expected by chance based on an alpha of .05 (i.e., 31). Among 3-year-olds, 9 children (3 boys and 6 girls) made more disadvantageous choices than would be expected by chance, whereas only 4 children (1 boy and 3 girls) made more advantageous choices. Among 4-year-olds, only 2 children (1 boy and 1 girl) made more disadvantageous choices, whereas 10 children (6 boys and 4 girls) made more advantageous choices. 3. Experiment 2 Three-year-olds in Experiment 1 tended to choose disadvantageously, as did those in Kerr and Zelazo’s (2004) study. We wondered whether their maladaptive choice was attributable to their difficulty in learning the gain/loss schedule, a candidate mechanisms for age differences in AMD. If schedule learning was made easier by increasing punishment frequency and magnitude in the bad deck, would younger perform better? To address this question we developed a variant of the CGT with losses more frequent and larger in the disadvantageous deck. Specifically, the proportion of gain cards was reduced to 31% (originally 48%) whereas cards with 4, 5, or 6 losses were increased to a total of 69% (originally 52%). These changes increased the average discrepancy between the disadvantageous and advantageous deck from 1.07 to 1.42 in the loss proportion. With this manipulation, children should learn more easily the gain/loss schedule and the distinct properties of the two decks. Another goal of Experiment 2 was to assess more across a broader range than that employed by age-related changed in AMD. Notably, Kerr and Zelazo (2004) and Experiment 1. Although both studies show age-related improvement in ADM, 4-year-olds did not show optimal performance. In Experiment 2, therefore, a group of 5-year-olds was added. Doing so will begin to close the gap between studies of
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AMD in preschool children and the more numerous studies of older children (Crone & van der Molen, 2004, 2007; Crone et al., 2005; Garon & Moore, 2004; Hooper et al., 2004; Overman, 2004; Peters & Slovic, 2000; Suhr & Tsanadis, 2007; Turnbull et al., 2005). 3.1. Method 3.1.1. Participants Sixty 3-year-olds (M = 42.6 months, range = 36–47 months, S.D. = 3.1), 61 four-year-olds (M = 54.1 months, range = 48–59 months, S.D. = 3.2), and 60 five-year-olds (M = 67.0 months, range = 60–71 months, S.D. = 3.3), were randomly recruited from day-care centers in Chongqing, China. Thirty of the 3-year-olds were boys and 29 of each of the other two ages groups were boys. None had participated in Experiment 1. 3.1.2. Materials The materials were identical to those in Experiment 1, except the disadvantageous deck was modified to contain 16 cards with 0 losses, 11 cards with 4 losses, 10 cards with 5 losses, and 16 cards with 6 losses; thus 10 choices would yield a net average loss of 16 candies. The sequence of gain/loss contingencies was fixed in a given order different from that in Experiment 1. 3.1.3. Procedure The procedure was the same as in Experiment 1. 3.2. Results and discussion Difference scores were analyzed by ANOVA as in Experiment 1. In comparing 3- and 4-year-olds, there was a significant main effect of age, F(1, 117) = 25.812, p < .0001, and a significant age × block interaction, F(4, 468) = 13.036, p < .000. The difference between 4- and 5-year-olds was not significant, F(1, 117) = 0.037, p > .05, nor was the age × block interaction, F(4, 468) = 0.836, p > .05. Tests of simple effects indicated that scores increased across blocks for 4-year-olds, F(4, 240) = 25.190, p < .0001, and 5-yearolds, F(4, 236) = 26.364, p < .0001, but not 3-year-olds, F(4, 236) = 0.438, p > .05. Four-year-olds made more advantageous choices than 3-year-olds on all the blocks (Fblock1 = 4.842, p < .05; Fblock2 = 7.886, p < .01; Fblock3 = 26.932, p < .000; Fblock4 = 25.799, p < .000; Fblock5 = 30.635, p < .000). In contrast, 4- and 5-year-olds performed similarly in all blocks. These results are illustrated in Fig. 2. We used the binomial theorem to determine whether each child made more advantageous or disadvantageous choices across 50 trials than would be expected by chance based on an alpha of .05 (i.e., 33 or more). Among 3-year-olds, 13 children (6 boys and 7 girls) made more disadvantageous choices
Fig. 2. Performance of children at different ages across blocks in Experiment 2.
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than would be expected by chance, and 10 children (6 boys and 4 girls) made more advantageous choices. Among 4-year-olds, none made more disadvantageous choices, whereas 33 children (19 boys and 14 girls) made more advantageous choices. Similarly, none of the 5-year-olds made more disadvantageous choices, whereas 33 of them (18 boys and 15 girls) made more advantageous choices. A main effect of gender favoring boys approached conventional significance, F(1, 175) = 3.750, p = 0.054, and a significant sex × block interaction appeared, F(4, 700) = 4.161, p < .01. On the last 4 trial blocks there emerged a significant sex difference, F(1, 175) = 5.170, p < .05, and a significant sex × age × block interaction, F(6, 525) = 2.366, p < .05. No significant sex difference emerged at the age of 3, or 5, but a sex difference was significant among 4-year-olds, F(1, 59) = 4.361, p < .05. In sum, the findings of Experiment 2 confirmed those of Experiment 1 as well as the findings of Kerr and Zelazo (2004), indicate that performance on the CGT improves from 3 to 4 years of age. Further, this development does not continue its trajectory into the fifth year. To gain some qualitative insight into younger children’s performance, we collected oral reports from 33 three-year-olds immediately after they finished the task. When asked, “Do you know which deck of cards can help you gain candies”, 18 children responded “yes” and pointed to the advantageous deck. Of the 18 children, 11 did not make more advantageous choices than would be expected by chance and only 7 chose significantly advantageously. Thus, children might not do well in the task even if they have gained some understanding of the contingency structure. This reinforced the notion that contingency learning alone cannot explain satisfactorily the ADM deficit of 3-year-olds. 4. General discussion The present study created a variant of the CGT by presenting delayed punishment in higher frequency and magnitude in the advantageous deck so as to make it easier to learn the gain/loss schedule and appreciate the value of each deck. The purpose was to reduce the potential influence of the ability to learn the gain/loss schedule. In Experiment 1, we examined the development of ADM between 3 and 4 years of age, employing an alternative version of the IGT, the CGT (Kerr & Zelazo, 2004). In Experiment 2, 3- to 5-year-olds were tested on a modification of the CGT. Performance showed significant improvement between 3 and 4 years but not between 4 and 5 years. The two experiments suggest that ADM develops rapidly between 3 and 4 years of age, consistent with previous findings (Garon & Moore, 2007; Kerr & Zelazo, 2004). Our findings suggest that modest differences in the gain/loss discrepancy between the advantageous and disadvantageous decks do not qualitatively influence this pattern. However, the CGT is a complex decision-making task that likely involves several inter-related abilities and demands cognitive–affective integration or interaction. In the task learning process preschoolers can hardly calculate exact net gains and losses under such uncertainty. Comprehension will be based on approximation. Contingency learning may, to some degree, be influenced by working memory or inductive learning variability. However, there is no evidence that memory or inductive learning processes are isolated from affective processes. We do not think that the gain/loss schedule is cognitively impenetrable or that emotion works in the absence of cognitive functions. Such learning may involve cognitive–affective integration or interaction, in which knowledge of the task contingencies, overt or covert, is developed by feeling and/or by reasoning. Thus, different contexts may make one element more important than another. It is unlikely that one function alone is entirely responsible for human decision-making in a complex task like the IGT and the CGT. Therefore, we must further evaluate the extent to which different factors contribute to performance by different age groups. Experiment 2 indicated that the development of ADM may be superior in boys in early childhood, which parallels the sex difference found by Kerr and Zelazo (2004) and by Overman et al. (1996) in infants and toddlers on a simpler measure of OFC function—object reversal. Male advantage in ADM has also been detected in school-aged children and adolescents (Crone et al., 2005; Crone & van der Molen, 2007; Overman et al., 2003) and adults (Bolla, Eldreth, Matochik, & Cadet, 2004; Reavis & Overman, 2001). Using the IGT with a large sample of adolescents, D’Acremont and van der Linden (2006) found a clear female advantage in decision-making, possibly as a result of boys’ more frequent risk-taking behavior. The unexpected female advantage found by Garon and Moore (2004) is probably due to some important differences between their task and some other versions of the IGT (see Garon & Moore, 2004, for a review). Similarly, the sex difference in our second experiment may be attributable
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to either a larger sample or the likelihood that increasing punishment in frequency and magnitude amplified the sex difference. Finally, in addition to the potential mechanisms discussed above, there are still some other factors that may influence children’s performance on the CGT, such as risk-taking (see Dunn et al., 2006, for a review) and personality. The current research revealed notable individual differences in performance within each age group. At each age, some children made a majority of advantageous choices, while others made a majority of disadvantageous choices. There is evidence that adult performance on a variant of the IGT is associated with self-report measures of personality (Peters & Slovic, 2000). Individuals rated in negative affectivity tended to avoid high losses, and individuals high in positive affectivity tended to seek high gains. Suhr and Tsanadis (2007) demonstrated that personality (funseeking) was correlated with adult performance on the IGT. Davis, Pattea, Tweed, and Curtis (2007) detected some relations between adult performance on a version of the IGT and personality traits such as impulsivity and addiction. In the present study, some children did show obvious risk-taking behavior. Nevertheless, Franken and Muris (2005) reported that behavioral decision-making was not predicted by impulsive personality traits. Risk-taking was found not significantly correlated with performance on the IGT (Overman, 2004). In brief, accounts of the relation between individual personality and IGT performance are controversial. The issue of personality seems as intriguing as sex differences on the IGT and the CGT. Yet these questions, and more precise decomposition of the complex decision-making involved in the CGT, inspire our future efforts. Acknowledgements We wish to give our sincere thanks to Gedeon O. Deák and Philip D. Zelazo for their helpful suggestions. 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