Genes and Child Development

Newsweek recently published an article featuring some of the latest research in developmental psychology. Interestingly, specific gene loci may be responsible for many of the behavioral differences seen in children.

Temperament, for example, has a strong genetic link with associated behavioral consequences. Children with easy temperaments are less likely to pay attention to their parents and to listen to them. Fussy children, on the other hand, are more likely to pay close attention to their environment (including their parents) and are, thus, more likely to learn from experience.

The article discusses genetic variations other than the mellow/fussy baby. The gene FADS2, for example, raises IQ scores for babies who have been breast fed. However, the "C" variant of the gene, possessed by about 10% of babies, does not lead to a similar rise in IQ scores. Another gene, MAOA, comes in "sluggish" and "active" forms. The sluggish version of that gene seemingly protects victims of abuse from later risky behavior because memories of the trauma are damped by that version of the gene. The active version, unfortunately, rekindles the traumatic memories and may lead the victim into alcohol or drug abuse as a coping mechanism. Another gene, DRD4, has been linked to a variety of behaviors from increasing coping behavior in children and increased sexuality.

The implications this line of research are varied. For one thing, it multiplies the amount of individual variation previously suspected. For another, it causes researchers and practitioners to look more closely for genetic causes for behavior. Finally, it makes the entire behavioral picture much more complicated than previously thought.

Concrete or Abstract?

Concrete examples or abstract examples? I have struggled with this issue in lectures and in writing. Usually, I opt for concrete example first followed by the more general, abstract case.

My rationale for this approach has been the results from the Wason Selection task. That logical problem (If P then Q, if Not P then Not Q is the solution to both cases) is solved much, much more often in its concrete form (~75% of the time) than in its abstract form (~5% of the time). Here is a site that explains this problem.

However, recent research from the Ohio State University (as reported in the New York Times) in mathematics education suggests that teaching the abstract first is far superior to teaching the concrete first in mathematics problems. This research was recently reported in the journal Science. The authors are Jennifer A. Kaminski, Vladimir M. Sloutsky, and Andrew F. Heckler.

To me, the discrepancy between the Wason Selection data and the Kaminski et. al data indicates that further research is needed. I agree that flying by the seat of one's pants is not a good idea here. It would be nice for teachers to know, once and for all, which strategy is best.

By the way, I sometimes use an abstract first strategy. Recall my earlier post on the Mastermind game. There I use an abstract first-first strategy to teach about main effects and interactions.

Erratum-Page 286

Here is the first of what we hope will prove to be a very short list of errata.

Shawn Powell of Casper College wrote:

"I have a question on a formula and significance test results shown on page 286. What was the df for MS residual and the number of levels of the IV used to arrive at the probability figures near the bottom of the page. Using the charts provided on pages 449 and 450 (which by the way are shown as "-" in the text on page 286) I used a df of 18 and an IV level of 2 and arrived at .05 = 2.97 and .01 = 4.07. If this is correct then the values to the right of the formula don't match up with the results shown."

Chris Spatz responded:

"To determine correct HSD critical values, the number of levels of the IV is the number in the original ANOVA problem rather than the number in the HSD test. Thus, for the HSD tests on page 286, the number is 3 and not the 2 in the HSD test. I'm afraid that our last paragraph on the page really needs some improving. Our only clue to you to use 3 is the word ANOVA. Upon re-reading, it is clear that the insertion of the numbers needed for the critical values (df = 18 and number of levels = 3) would improve the communication of what we actually did."

In addition, there is a typographical error in the last paragraph of page 286. The first two sentences should read:

"To interpret HSD values, use Table C.5 in appendix C. Critical values for alpha = .05 are on page 449 (missing page number in original); those for alpha = .01 are on page 450 (missing page number in the original)."

Our thanks to Dr. Powell and his sharp eyes. If anyone else spots similar issues please contact us.

Mastermind and Interactions

The board game, Mastermind, can be used to demonstrate interactions and main effects in an abstract way.

Here is Wikipedia's description of Mastermind (click here). Downloadable versions of Mastermind can be found near the bottom of that page. Finding original games is still possible. Try an eBay search for Mastermind, for instance.

Playing Mastermind is, ultimately, a search for the interaction of its two variables (a.k.a. main effects) peg color and peg position. A player wins when the opponent's pattern of pegs has been decoded. During play, the coding player provides feedback (or, values for a dependent variable) using white or black pegs. A white peg indicates that the correct color of a peg has been decoded, but that the peg is not in the correct position. A black peg indicates that both the color of the peg and its position are correct. The decoding player wins when all of the feedback pegs are black.

Mastermind can also be used to illustrate (again, in an abstract way) effective experimental design. Decoding players who do not plan their decoding stategy will nearly always fail to discover the coded pattern. Try a game or two.