Interference Theory (IT)[1]
The knowledge I previously gathered and shared regarding Working Memory (WM), Cognitive Load Theory (CLT), and Attention helped me understand the factors that influence WM load. Through the deliberate application of Active Attention I’ve been able to effectively engage with those factors. This time, I’d like to draw on the Interference Theory (IT) as presented in Sternberg & Sternberg, to explain how the method illustrated in the two practice examples above relates to the psychological law of forgetting.
Interference Theory (IT) describes how forgetting occurs when the effort to recall certain information interferes with the ability to recall other information.[2] IT is categorized into two types: Proactive Interference (PI) – when prior knowledge disrupts the learning or recall of new information (old blocks new) and Retroactive Interference (RI) – when newly learned information interferes with the recall of previously acquired knowledge (new blocks old).
So, what are the key factors that influence PI and RI? Research has identified the following as significant:
(1) Length of each information unit: For example, LXVII causes more interference than XII.[3]
(2) Number of intervening items: The more items introduced in between, the greater the interference.[4]
(3) Time interval between initial encoding and attempted recall: The longer the delay, the more likely forgetting will occur. This is a natural law of memory—over time, memory traces fade if not reinforced. This phenomenon is addressed in Decay Theory.[5]
(4) Number of repetitions. The fewer times the information is repeated or reviewed, the harder it is to recall.
(5) Similarity between old and new information: The more alike they are, the greater the likelihood of confusion.[6]
(6) Salience, relative strength between old and new information: Competing strength makes recall more difficult.
Let’s apply these factors to understand what happened in Practice Example 2.
+ When I initially selected and memorized the Latin numbers and their respective colors, the length of the numeral strings, the variability in color, the time spent encoding each digit, the similarity between numbers (e.g., repeated use of X), and the mental rehearsal all activated the six factors mentioned above.
+ Then, when I lay down to practice, even just the minute spent adjusting my clothes and blanket (a time delay—factor 3) had passed. As I tried to recall and mentally draw each number and its colors, this delay and shifting of attention triggered Retroactive Interference (RI). RI was even more pronounced when recalling LXVII, due to its greater length (factor 1).
+ Next, when I tried to recall and draw XII, Proactive Interference (PI) occurred—part of WM was still occupied with remembering LXVII, making it harder to recall the correct color scheme for XII. Additionally, LXVII acted as an intervening item (factor 2) when I tried to focus on XII. The similarity in the character X between the two numerals further complicated accurate recall (factor 5).
+ When I began rearranging and combining components of LXVII and XII to create new figures, this process provided opportunities for repetition and review (factor 4). However, the number of new combinations I generated increased interference, while the limited consolidation time for those new elements reduced retention. As WM was forced to store and manage this growing complexity, it became fatigued. At that point, even the mere intention to add new and old numbers together caused a mental freeze. If I then tried to recall the remaining numbers (LIX, VI, IV) and their colors, WM would crash completely—overloaded beyond its capacity (factor 6).
In summary, the process of repeatedly moving back and forth, layering and mixing numbers in the example above perfectly aligns with the psychological laws of memory as explained in Interference Theory—and leads naturally to samādhi. While IT and CLT are typically understood in the context of improving learning efficiency, in meditation practice I deliberately reverse that objective. I use this psychological knowledge not to enhance memory or learning, but to lead the mind into stillness—into samādhi.
(End of Part 4/11)
Notes:
[1] Sternberg, R. J., and Sternberg, K. (2017). Cognitive Psychology (7th ed.). Boston, MA: Cengage Learning. See the section titled “Forgetting and memory distortion” on page 222. Additional reference https://www.cleverism.com/proactive-and-retroactive-interference-explained/.
[2] Research on Interference Theory dates back to the late 1950s, or perhaps even earlier. John A. Bergström is regarded as one of the pioneers of this theory. See https://en.wikipedia.org/wiki/Interference_theory; https://en.wikipedia.org/wiki/Hermann_Ebbinghaus.
[3] See Derks, P.L, 1974. The length-difficulty relation in immediate serial recall. Journal of Verbal Learning and Verbal Behavior 13, 335–354. This study shows that doubling the length of a number sequence can increase the time required for recall by up to sixfold.
[4] See Murre, J.M.J., and Dros, J., 2015. Replication and analysis of Ebbinghaus’ forgetting curve. PLOS ONE 10(7), 1–23. Rubin, D.C., Hinton, S., and Wenzel, A., 1999. The precise time course of retention. Journal of Experimental Psychology: Learning, Memory, and Cognition 25(5), 1161–1176. These studies use exponential decay models (power functions) to measure recall probability over short and long timeframes, in the presence of intervening information. For instance, Table A1 on page 1175 in Rubin et al. (1999) shows that just four intervening items (i.e., after learning item A, being exposed to B, C, D, and E) reduce recall accuracy of A to 38%. With seven intervening items, the recall rate drops to 34%.
[5] https://en.wikipedia.org/wiki/Decay_theory. Also, Keppel, G., and Underwood, B.J., 1962. Proactive inhibition in short-term retention of single items. Journal of Verbal Learning and Verbal Behavior 1, 153–161. Peterson, L.R., and Peterson, M.J., 1959. Short-term retention of individual verbal items. Journal of Experimental Psychology 58(3), 193–198. Findings from these studies indicate that after 3 seconds, recall accuracy for a set of three non-rhyming letters (e.g., K B F) is about 80%, but after 18 seconds, it drops to around 10%. Moreover, the sharpest decline occurs within the first 10 seconds.
[6] See Cybenko, A.K., 2011. Interference in a modified recognition task: An evaluation of the changed-trace and multiple-trace hypotheses. PhD thesis.
