Josefa N. S. Pandeirada

Adaptive Memory The Comparative Value of Survival Processing

We recently proposed that human memory systems are “tuned” to remember information that is processed for survival, perhaps as a result of fitness advantages accrued in the ancestral past. This proposal was supported by experiments in which participants showed superior memory when words were rated for survival relevance, at least relative to when words received other forms of deep processing. The current experiments tested the mettle of survival memory by pitting survival processing against conditions that are universally accepted as producing excellent retention, including conditions in which participants rated words for imagery, pleasantness, and self-reference; participants also generated words, studied words with the intention of learning them, or rated words for relevance to a contextually rich (but non-survival-related) scenario. Survival processing yielded the best retention, which suggests that it may be one of the best encoding procedures yet discovered in the memory field.

Adaptive Memory Remembering With a Stone-Age Brain

If memory evolved, sculpted by the processes of natural selection, then its operating characteristics likely bear the “footprints” of ancestral selection pressures. Psychologists rarely consider this possibility and generally ignore functional questions in their attempt to understand how human memory works. We propose that memory evolved to enhance reproductive fitness and, accordingly, its systems are tuned to retain information that is fitness-relevant. We present evidence consistent with this proposal, namely that processing information for its survival relevance leads to superior long-term retention—better, in fact, than most known memory-enhancement techniques. Even if one remains skeptical about evolutionary analyses, adopting a functional perspective can lead to the generation of new research ideas.

Adaptive Memory Fitness Relevance and the Hunter-Gatherer Mind

Recent studies suggest that human memory systems are “tuned” to remember information that is processed in terms of its fitness value. When people are asked to rate the relevance of words to a survival scenario, performance on subsequent surprise memory tests exceeds that obtained after most other known encoding techniques. The present experiments explored this effect using survival scenarios designed to mimic the division of labor thought to characterize early hunter-gatherer societies. It has been suggested that males and females have different cognitive specializations due to the unique survival tasks (hunting and gathering, respectively) they typically performed during periods of human evolution; the present experiments tested whether such specializations might be apparent in memory for words rated for relevance to these activities. Males and females were asked to rate the relevance of random words to prototypical hunting and gathering scenarios or to matched, non-fitness-relevant control scenarios (gathering food on a scavenger hunt or in a hunting contest). Surprise retention tests revealed superior memory for the words when they were rated for relevance to hunting and gathering scenarios, compared with when they were rated for relevance to the control scenarios, but no sex differences were found in memory performance.

Adaptive Memory The Mnemonic Value of Animacy

Distinguishing between living (animate) and nonliving (inanimate) things is essential for survival and successful reproduction. Animacy is widely recognized as a foundational dimension, appearing early in development, but its role in remembering is currently unknown. We report two studies suggesting that animacy is a critical mnemonic dimension and is one of the most important item dimensions ultimately controlling retention. Both studies show that animate words are more likely to be recalled than inanimate words, even after the stimulus classes have been equated along other mnemonically relevant dimensions (e.g., imageability and meaningfulness). Mnemonic “tunings” for animacy are easily predicted a priori by a functional-evolutionary analysis.

Congruity Effects in the Survival Processing Paradigm

Five experiments were conducted to investigate a proposal by Butler, Kang, and Roediger (2009) that congruity (or fit) between target items and processing tasks might contribute, at least partly, to the mnemonic advantages typically produced by survival processing. In their research, no significant survival advantages were found when words were preselected to be highly congruent or incongruent with a survival and control (robbery) scenario. Experiments 1a and 1b of the present report show that survival advantages, in fact, generalize across a wide set of selected target words; each participant received a unique set of words, sampled without replacement from a large pool, yet significant survival advantages remained. In Experiment 2, we found a significant survival advantage using words that had been preselected by Butler et al. to be highly unrelated (or irrelevant) to both the survival and control scenarios. Experiment 3 showed a significant survival advantage using word sets that had been preselected to be highly congruent with both scenarios. Finally, Experiment 4 mixed congruent and incongruent words in the same list, more closely replicating the design used by Butler et al., and a highly reliable main effect of survival processing was still obtained (although the survival advantage for the congruent words did not reach conventional levels of statistical significance). Our results suggest that the null effects of survival processing obtained by Butler et al. may not generalize beyond their particular experimental design.

Adaptive Memory Animacy Processing Produces Mnemonic Advantages

It is adaptive to remember animates, particularly animate agents, because they play an important role in survival and reproduction. Yet, surprisingly, the role of animacy in mnemonic processing has received little direct attention in the literature. In two experiments, participants were presented with pronounceable nonwords and properties characteristic of either living (animate) or nonliving (inanimate) things. The task was to rate the likelihood that each nonword-property pair represented a living thing or a nonliving object. In Experiment 1, a subsequent recognition memory test for the nonwords revealed a significant advantage for the nonwords paired with properties of living things. To generalize this finding, Experiment 2 replicated the animate advantage using free recall. These data demonstrate a new phenomenon in the memory literature - a possible mnemonic tuning for animacy - and add to growing data supporting adaptive memory theory.

Adaptive memory: enhanced location memory after survival processing.

Two experiments investigated whether survival processing enhances memory for location. From an adaptive perspective, remembering that food has been located in a particular area, or that potential predators are likely to be found in a given territory, should increase the chances of subsequent survival. Participants were shown pictures of food or animals located at various positions on a computer screen. The task was to rate the ease of collecting the food or capturing the animals relative to a central fixation point. Surprise retention tests revealed that people remembered the locations of the items better when the collection or capturing task was described as relevant to survival. These data extend the generality of survival processing advantages to a new domain (location memory) by means of a task that does not involve rating the relevance of words to a scenario.

Adaptive memory: Animacy effects persist in paired-associate learning

Recent evidence suggests that animate stimuli are remembered better than matched inanimate stimuli. Two experiments tested whether this animacy effect persists in paired-associate learning of foreign words. Experiment 1 randomly paired Swahili words with matched animate and inanimate English words. Participants were told simply to learn the English “translations” for a later test. Replicating earlier findings using free recall, a strong animacy advantage was found in this cued-recall task. Concerned that the effect might be due to enhanced accessibility of the individual responses (e.g., animates represent a more accessible category), Experiment 2 selected animate and inanimate English words from two more constrained categories (four-legged animals and furniture). Once again, an advantage was found for pairs using animate targets. These results argue against organisational accounts of the animacy effect and potentially have implications for foreign language vocabulary learning.

Adaptive Memory: The Evolutionary Significance of Survival Processing.

A few seconds of survival processing, during which people assess the relevance of information to a survival situation, produces particularly good retention. One interpretation of this benefit is that our memory systems are optimized to process and retain fitness-relevant information. Such a “tuning” may exist, in part, because our memory systems were shaped by natural selection, using a fitness-based criterion. However, recent research suggests that traditional mnemonic processes, such as elaborative processing, may play an important role in producing the empirical benefit. Boundary conditions have been demonstrated as well, leading some to dismiss evolutionary interpretations of the phenomenon. In this article, we discuss the current state of the evolutionary account and provide a general framework for evaluating evolutionary and purportedly nonevolutionary interpretations of mnemonic phenomena. We suggest that survival processing effects are best viewed within the context of a general survival optimization system, designed by nature to help organisms deal with survival challenges. An important component of survival optimization is the ability to simulate activities that help to prevent or escape from future threats which, in turn, depends in an important way on accurate retrospective remembering of survival-relevant information.

Source-constrained retrieval and survival processing

Three experiments investigated the mnemonic effects of source-constrained retrieval in the survival-processing paradigm. Participants were asked to make survival-based or control decisions (pleasantness or moving judgments) about items prior to a source identification test. The source test was followed by a surprise free recall test for all items processed during the experiment, including the new items (foils) presented during the source test. For the source test itself, when asked about the content of prior processing—did you make a survival or a pleasantness decision about this item?—no differences were found between the survival and control conditions. The final free recall data revealed a different pattern: When participants were asked to decide whether an item had been processed previously for survival, that item was subsequently recalled better than when the source query asked about pleasantness or relevance to a moving scenario. This mnemonic boost occurred across-the-board—for items processed during the initial rating phase and for the new items. These data extend the generality of source-constrained retrieval effects and have implications for understanding the proximate mechanisms that underlie the oft-replicated survival-processing advantage in recall and recognition.