What did memory evolve to do?
Humans have evolved over the course of millions of years. Since we last shared a common ancestors with chimpanzees more than 6 million years ago (White et al, 2009), a number of hominin species have evolved - most, of course, have died out (as recently as 100,000 years ago, 4-5 homo species existed concurrently).
For most of this time, our ancestors and near relatives probably lived in grasslands environments, hunting and gathering. This environment has shaped our physical bodies as well as our behaviour - from our appetite for fatty and sweet foods, to our large brains which facilitate cooperation and interactions in large tribes.
Role of evolution in memory
Beyond a general acknowledgement that our brains and cognitive abilities are the product of evolution, human memory research has largely ignored our evolutionary history, focusing on short-term processing (see Bahrick, 2005) and using tasks which take little account of the context in which things are encountered in the real world.
An important advance was made when James Nairne and colleagues conducted an experiment demonstrating that people remember information better when they process it in a grasslands scenario. In an ingenious study, participants were shown a list of words such as truck, juice, chair and sword and were then asked to rate how relevant these objects were to the following scenario:
Remarkably, in a later surprise test, participants remembered the words significantly better having thought about them in this context compared to the other conditions used in the experiment - one of which involved a moving house scenario, and the other required participants simply to think about the pleasantness of the word (a standard memory intervention which promotes deep processing).
If this sounds like a fluke, the effect has been replicated several times and by many different researchers; other comparison scenarios have been tried - for example a bank robbery (Kang et al, 2008), zombies in the city (Soderstrom & McCabe, 2011), and even an 'in the afterlife' scenario (Röer et al, 2013) - but none have proved superior or even equal in promoting recall of a set of items.
Is this truly 'survival processing'?
A simple but very general question arises from this work - assuming that our evolution has prepared us to do certain things better than others, how specific are these abilities? Have we really been hard-wired to process grasslands survival situations better than other situations in a way that affects all of human memory today?
Alternatively, is the grasslands research scenario somehow drawing on a more general aspect of memory that the other scenarios fail to tap into?
My reading of the research literature so far gives the impression that many researchers are trying their best to demonstrate the latter. Three particularly interesting possibilities include:
- It causes us to plan more more than other scenarios, and planning leads to better encoding to memory (Klein, 2014).
- It causes us to encode items more richly (Bell et al, 2015). Elaborative encoding is well known to benefit long-memory - which, after all, is based on making meaningful connections.
- It allows for more creative thinking in terms of how the objects are used. In keeping with this possibility, Wilson (2016) found that a grasslands scenario was also better at promoting creative thinking about object uses than any of the other widely used comparison conditions. If we think creatively about something, we may well remember it better due to the generation effect.
The exact variables at play are still under investigation, and it could be a combination of these factors - the grasslands scenario may promote more creative, future-focused and meaningful thought processes. It is curious, however, how no other scenario has so far proved to be comparably successful in boosting memory - at least with the original tasks and materials.
What does this mean for education?
As a relatively new area of research, survival processing has not yet had a significant impact on education, but it does have potential. With further testing, a set of principles could be established, allowing classroom activities to be designed to incorporate elements of risk/danger, future planning, creativity, etc.
Survival processing is not the only possible effect of evolution on memory that could impact on education. For example, we also remember animals better than inanimate objects - an effect which has been trialled for use in the learning of language vocabulary (Nairne, 2016).
More broadly, many of the most robust findings from the study of memory make perfect sense from an evolutionary perspective. The spacing effect, for example, fits with the idea that any animal needs to deal with a one-off problem, but needn't waste mental resources storing the responses long-term. In contrast, if something happens periodically with time gaps in between - a type of food that grows seasonally, migrating predators or occasional floods, for example - the adaptive response is to create a more lasting mental record of any any relevant details as well as successful responses that we have previously used.
Similarly, the perspective that students learn better if tasks connect to their interests and social context makes a lot of sense from a survival point of view (at least for social species such as our own), as does the idea that interleaving our learning - something that would happen a lot in the natural world - is advantageous in the 'inductive learning' of patterns and rules.
The classic Zeigarnik effect - incomplete tasks being better remembered than complete ones - also fits well with a scenario where an unfinished task could be a matter of life or death.
Clearly, we can't deliver entire school courses via a grasslands scenario like the one described above. We could, however, pay more attention to the ways in which memory has evolved to work, and establish ways of building these principles into classroom tasks.
Bahrick, H. P. (2005). The long-term neglect of long-term memory: Reasons and remedies. In A.F. Healy (Ed.), Experimental Cognitive Psychology and its Applications. Washington, DC: American Psychological Association.
Bell, R., Röer, J.P. & Buchner, A. (2015) Adaptive Memory: Thinking about function. Journal of Experimental Psychology: Learning, Memory & Cognition, 41, 1038 – 1048 http://dx.doi.org/10.1037/xlm0000066
Kang, S. H., McDermott, K. B., & Cohen, S. M. (2008). The mnemonic advantage of processing fitness-relevant information. Memory & Cognition, 36(6), 1151-1156.
Klein, S.B. (2014). Evolution, memory and the role of self-referrant recall in planning for the future. In B.L. Schwarz, M.L. Howe, M.P. Toglia and H. Otgaar (Eds.) What is Adaptive about Adaptive Memory? pp. 11-34. Oxford: OUP.
Nairne, J. S. (2016). Adaptive Memory: Fitness-Relevant “Tunings” Help Drive Learning and Remembering. In D.C. Geary & D.B. Berch (Eds), Evolutionary Perspectives on Child Development and Education (pp. 251-269). New York: Springer.
Nairne, J. S., Thompson, S. R., & Pandeirada, J. N. (2007). Adaptive memory: survival processing enhances retention. Journal of Experimental Psychology: Learning, Memory, and Cognition, 33(2), 263.
Röer, J. P., Bell, R., & Buchner, A. (2013). Is the survival-processing memory advantage due to richness of encoding?. Journal of Experimental Psychology: Learning, Memory, and Cognition, 39(4), 1294.
Soderstrom, N. C., & McCabe, D. P. (2011). Are survival processing memory advantages based on ancestral priorities?. Psychonomic Bulletin & Review, 18(3), 564-569.
White, T. D., Asfaw, B., Beyene, Y., Haile-Selassie, Y., Lovejoy, C. O., Suwa, G., & WoldeGabriel, G. (2009). Ardipithecus ramidus and the paleobiology of early hominids. Science, 326(5949), 64-86.
Wilson, S. (2016). Divergent thinking in the grasslands: thinking about object function in the context of a grassland survival scenario elicits more alternate uses than control scenarios. Journal of Cognitive Psychology, 1-13.