Proactive interference and the development of working memory

Working Memory (WM), the ability to maintain information in service to a task, is characterized by its limited capacity. Several influential models attribute this limitation in a large extent to proactive interference (Anderson & Neely, 1996; Bunting, 2006; Kane & Engle, 2000), the phenomenon that previously encoded, now-irrelevant information competes with relevant information (Keppel & Underwood, 1963). Here, we look back at the adult PI literature, spanning over sixty years, as well as recent results linking the ability to cope with PI to WM capacity (Endress & Potter, 2014; Kane & Engle, 2000). In early development, WM capacity is even more limited (Kaldy & Leslie, 2005; Simmering, 2012), yet an accounting for the role of PI has been lacking. Our Focus Article aims to address this through an integrative account: since PI resolution is mediated by networks involving the frontal cortex (particularly, the left inferior frontal gyrus) and the posterior parietal cortex (Badre & Wagner, 2005; Jonides & Nee, 2006), and since children have protracted development and less recruitment (Crone et al., 2006) of these areas, the increase in the ability to cope with PI (Kail, 2002; De Visscher & Noel, 2014) is a major factor underlying the increase in WM capacity in early development. Given this, we suggest that future research should focus on mechanistic studies of PI resolution in children. Finally, we note a crucial methodological implication: typical WM paradigms repeat stimuli from trial-to-trial, facilitating, inadvertently, PI and reducing performance; we may be fundamentally underestimating children’s WM capacity.

Individual differences in proactive interference in rats (Rattus Norvegicus)

Individual differences in behaviors are seen across many species, and investigations have focused on traits linked to aggression, risk taking, emotionality, coping styles, and differences in cognitive systems. The current study investigated whether there were individual differences in proactive interference tasks in rats (Rattus Norvegicus), and tested hypotheses suggesting that these tasks should load onto a single factor and there should be clusters of rats who perform well or poorly on these tasks. The performance of 39 rats was tested across three learning tasks that all involved disengagement from an irrelevant previously learned stimulus to a relevant stimulus: latent inhibition (LI), partial reinforcement extinction effect (PREE), and reversal learning (RL). An exploratory factor analysis revealed the existence of one factor underlying performance. A cluster analysis revealed the existence of sets of rats displaying either weak LI and strong PREE and RL effects, or vice versa. These findings suggest that proactive interference may be based on a single underlying psychological system in rats.

The Effect of Forward Testing as a Function of Test Occasions and Study Material

It has long been known that one of the most effective study techniques is to be tested on the to-be-remembered material, a phenomenon known as the testing effect. Recent research has also shown that testing of previous materials promotes the learning of new materials, a phenomenon known as the forward testing effect. In this paper, as of yet unexplored aspects of the forward testing effect related to face-name learning are examined; continuous and initial testing are compared to restudying, the effects of an initial test on subsequent learning, and whether an initial change of domain (change from one topic to another) regarding study material affects the robustness of the effect. An experiment (N = 94) was performed according to a 2 (Material: word pairs/face-name pairs in Block 1) × 3 (Test occasions: Blocks 1–4/Blocks 1 and 4/Block 4) complex between-groups design. The results showed that no difference between testing and repetition could be observed regarding the recall of faces and names. The restudy groups incorrectly recalled more names from previous lists in the last interim test compared to the tested groups, which supports the theory that interim tests reduce proactive interference. The results also suggest that the number of test occasions correlates with the number of incorrect recalls from previous lists. These results, in contrast to previous studies, highlight a potential uncertainty about the forward testing effect linked to the robustness of the phenomenon, the specificity in execution, and generalizability.

Elementary math in elementary school: To learn the multiplication table, avoid proactive interference

A major challenge for elementary school students is memorizing the multiplication table. This is difficult because there are many facts to learn and they are similar to each other, which creates proactive interference in memory. Here, we examined whether reducing interference would improve the memorization of the multiplication table by first graders. In a series of 16 short training sessions over a period of 4 weeks, each child learned 16 multiplication facts – 4 facts per week. Learning was better when the 4 facts in a given week were dissimilar from each other, a situation that reduces the proactive interference among them. Critically, this similarity effect originated in the specific learning context, i.e., the grouping of facts to weeks, and could not be explained as an intrinsic advantage of some facts over others. The similarity effect persisted 5 weeks after the end of the training period, i.e., proactive interference affected the long-term memory. Furthermore, during training, the similarity effect was not observed immediately but only in later training sessions, and only when examined in the beginning of a session. This indicates that proactive interference affected the long-term memory directly – it did not originate in short-term memory processes and then “leak” to long-term memory. We propose that the effectivity of this low-interference training method, which is dramatically different from currently-used pedagogical methods, calls for a serious reconsideration of the way we teach the multiplication table in school.

The contribution of episodic Long-term Memory to Working Memory for Bindings.

The Binding Hypothesis of working memory (WM) is that WM capacity is limited by interference between bindings but not items. It implies the prediction that with increasing set size, memory for bindings should decline, whereas memory for items should be (largely) unimpaired. Here we test the binding hypothesis for bindings between words and pictures. The first experiment supported the binding hypothesis, yet also revealed a strong hint that episodic LTM contributed substantially to binding memory, especially at larger set sizes. Therefore, our second goal was to investigate this contribution, and to isolate it from the contribution of WM to binding memory. Across three additional experiments we showed a double dissociation of contributions of WM and episodic LTM to binding memory: Performance at set sizes larger than 3 were specifically affected by proactive interference – but were immune to influences from a distractor filled delay. In contrast, performance at set size 2 was unaffected by proactive interference but harmed by a distractor filled delay.

Association of physical activity on memory interference: Boston Puerto Rican Health Study

Background: The objective of this study was to evaluate the association between habitual physical activity engagement on memory interference. The present analysis used cross-sectional data from the Boston Puerto Rican Health Study (n=1,241; mean age= 57.2; 72.1% female). Methods: Physical activity was evaluated via self-report. Memory interference was evaluated using a word-list paradigm. The memory task included learning a list of 16 words (List A; 5 trials), followed by a distractor list (List B), and then an immediate recall of List A. Proactive interference occurs when preceding stimuli (e.g., Trial 1 and Trial 5 of List A) interferes with performance on a subsequent stimuli (List B). Retroactive interference occurs when subsequent stimuli (List B) interferes with the recall of previously encoded stimuli (Trial 5). Results: For proactive interference, there was no association between physical activity and the difference between performance on List B and Trial 1 of List A (β=0.00001; P=0.96). Similarly, for retroactive interference, there was no association between physical activity and the difference between the short delay recall and Trial 5 of List A (β=0.0002; P=0.50). Conclusion: The present study did not observe an association between habitual physical activity on attenuating memory interference.