Sometimes wind turbine blades fall off, and this phenomenon occurred last week in Iowa, as a 165 foot blade fell into a harvested field. According to Renew Economy, this followed a similar incident in September at MidAmerican’s Arbor Hills wind farm in Adair County, where a turbine blade broke off a turbine and fell into a cornfield. And at the company’s Orient wind farm, also in Adair County, blades broke from turbines in April of this year and October 2019.
A news story after the September blade failure is of particular interest. I’d encourage you to watch it by clicking on the picture below.
The Iowa Gambling Task (IGT) is a sequential learning task in which participants develop a tendency towards advantageous options arising from the outcomes associated with their previous decisions. The role of working memory in this complex task has been largely debated in the literature. On one hand, low working memory resources lead to a decrease in the number of advantageous decisions.
- The original Iowa Gambling Task studies decision making using a cards. The participant needs to choose one out of four card decks (named A,B,C, and D). The participant can win or loose money with each card. The task was designed by Bechera and colleagues, 1994.
- List of casinos in the U.S. State of Iowa; Casino City County State District Type Comments Ameristar Casino Council Bluffs: Wikimedia Commons has media related to Casinos in Iowa.
The latest blade failure, which has been called a “blade detachment incident,” has prompted MidAmerican to temporarily shut down 46 turbines until they have been inspected and any potential problems are fixed.
MidAmerican believes that the blade failure was caused by faulty lighting channeling equipment that is supposed to prevent lighting strikes from causing severe damages to the blades. You can read more about these systems here.
Thus far it appears the turbine blade failures are the result of faulty equipment on Vestas-made turbines. American Experiment will continue to update our readers on future blade failure events.
Sample
Iowa Gambling Experiment Videos
Table 1 describes the data pool. All included studies used (a variant of) the traditional IGT payoff scheme 1 or the payoff scheme introduced by Bechara & Damasio 2. A detailed description of the payoff schemes can be found in the Supplemental Text 1.
Table 1
Overview of the studies included in the data pool. See text for a description of the different payoff schemes.
| Study | Number of participants | Number of trials | Payoff | Demographicsa |
|---|---|---|---|---|
| Fridberg et al. 3 | 15 | 95 | 1 | M = 29.6 years (SD = 7.6) |
| Horstmannb | 162 | 100 | 2 | M = 25.6 years (SD = 4.9), 82 female |
| Kjome et al. 5 | 19 | 100 | 3 | M = 33.9 years (SD = 11.2), 6 female |
| Maia & McClelland 6 | 40 | 100 | 1 | Undergraduate students |
| Premkumar et al. 7 | 25 | 100 | 3 | M = 35.4 years (SD = 11.9), 9 female |
| Steingroever et al. 8 | 70 | 100 | 2 | M = 24.9 years (SD = 5.8), 49 female |
| Steingroever et al. 9 | 57 | 150 | 2 | M = 19.9 years (SD = 2.7), 42 female |
| Wetzels et al. 15c | 41 | 150 | 2 | Students |
| Wood et al. 16 | 153 | 100 | 3 | M = 45.25 years (SD = 27.21)d |
| Worthy et al. 17 | 35 | 100 | 1 | Undergraduate students, 22 female |
aInformation that was provided in the original articles. This information consists of the mean age and the standard deviation in brackets, or alternatively the occupation of the participants. In addition, the number of female participants is provided for most datasets.
bData collected by Annette Horstmann. These data were first published in Steingroever et al. 10. A subset of this dataset is published in Horstmann, Villringer, and Neumann 4.
cData of the standard condition. Data of three other conditions can be downloaded here: http://www.ruudwetzels.com/data/EV_data.zip.
Iowa Gambling Experiment Rules
dThe first 90 participants of this dataset are between 18–40 years old (M = 23.04, SD = 5.88), and participants 91–153 are between 61 and 88 years old (M = 76.98, SD = 5.20).
In the traditional payoff scheme, the net outcome of 10 cards from the bad decks (i.e., decks A and B) is −250, and +250 in the case of the good decks (i.e., decks C and D). In addition, there are two decks with frequent losses (decks A and C), and two decks with infrequent losses (decks B and D). In the traditional payoff scheme, there is a variable loss in deck C (i.e., either −25, −50, or −75; classified here as payoff scheme 1). However, some of the included studies used a variant of this payoff scheme in which the loss in deck C was held constant (i.e., −50; classified here as payoff scheme 2). A second difference between payoff scheme 1 and 2 is that payoff scheme 1 uses a fixed sequence of rewards and losses, whereas payoff scheme 2 uses a randomly shuffled sequence.
Iowa Gambling Experiment Game
The payoff scheme introduced by Bechara & Damasio 2 (classified here as payoff scheme 3) also consists of two good decks (decks C and D), and two bad decks (decks A and B), that vary in either having frequent losses (decks A and C) or infrequent losses (decks B and D). However, in contrast to payoff schemes 1 and 2, the schedules of rewards and losses in payoff scheme 3 are structured in such a way that the discrepancy between rewards and losses in the bad decks (decks A and B) changes such that the net outcome decreases by 150 every block of 10 cards (i.e., in the first block, the net outcome is −250, but in the sixth block, it is −1000). By contrast, the net outcome of the good decks (decks C and D) increases by 25 every block of 10 cards (i.e., in the first block, the net outcome is 250, but in the sixth block, it is 375). Thus, the good decks become gradually better, whereas the bad decks become gradually worse. In addition, in contrast to payoff schemes 1 and 2, the wins differ within each deck in payoff scheme 3. Just as payoff scheme 1, payoff scheme 3 uses a fixed sequence of wins and losses.