Can the precision with which items are retained in visual working memory (VWM) be altered? Participants were shown displays containing 4 or 8 bars. The bars were colored red or green to indicate whether fine or coarse memory precision would be needed to perform the task. One of the bars was then rotated 15 (fine) or 45 (coarse) degrees, and participants had to indicate if the bar had been rotated clockwise or counterclockwise. Contralateral delay activity -- a neural marker of VWM -- was greater on trials with 4 bars than on trials with 8 bars only when participants anticipated having to use fine precision. These findings indicate that people can enhance the precision of items in their VWM when there are a small number of items.
Sara R. Jaffee, Ken B. Hanscombe, Claire M. A. Haworth, Oliver S. P. Davis, and Robert Plomin
The authors of this study were interested in understanding the genetic and environmental influences on the relationship between chaotic households and disruptive behavior in children. Twins reported their perceived level of household chaos, and parents reported their children's level of disruptive behavior at ages 9 and 12. Researchers found a cross-lagged relationship indicating that environmental influences on children's perceptions of household chaos at age 9 explained some of the environmental variation in children's disruptive behaviors at age 12. This suggests that the effect of household chaos at age 9 on disruptive behaviors at age 12 was environmentally mediated.
Peter P. J. L. Verkoeijen, Samantha Bouwmeester, and Gino Camp
Researchers know that repeated testing leads to better long-term memory for information than does repeated study; however, they are still unsure of why this occurs. Researchers had Dutch-English bilingual participants learn several lists of words in Dutch. In some instances they were tested after an initial study period (test condition), and in others they were told to study the list again (restudy condition). Participants' memory for the words was then tested in Dutch or English. Words in the restudy condition were remembered more poorly when participants were tested in English than when they were tested in Dutch; whereas words in the test condition were remembered similarly regardless of the language used. This indicates there are differences in the way restudying and testing strengthen memory.
The rate at which we forget information can be mathematically described by power functions. Traditionally the form of the functional relationship depends on the scale used by for the variable of interest. In this experiment, participants studied a list of 12 items and were tested on their memory for the items. The authors discovered that a version of the exemplar recognition model that assumes a lag-based power law was a better fit for both the participant's responses and their response times than a variety of other models. The fact that the model was a good fit for both variables even though they were measured on different scales indicates that the model was independent of the variable scale used, suggesting a possible power law of memory strength.