Does the thought of death contribute to the memory benefit of encoding with a survival scenario?

Semantic determinants of memorability

We examine why some words are more memorable than others by using predictive machine learning models applied to word recognition and recall datasets. Our approach provides more accurate out-of-sample predictions for recognition and recall than previous psychological models, and outperforms human participants in new studies of memorability prediction. Our approach's predictive power stems from its ability to capture the semantic determinants of memorability in a data-driven manner. We identify which semantic categories are important for memorability and show that, unlike features such as word frequency that influence recognition and recall differently, the memorability of semantic categories is consistent across recognition and recall. Our paper sheds light on the complex psychological drivers of memorability, and in doing so illustrates the power of machine learning methods for psychological theory development.

Is there a survival processing effect in metacognition?

Memory systems serve an adaptive function for the fitness of organisms. A good example of this is the Survival Processing Effect (SPE) which points to increased retention of information when it is processed in a survival context compared to other contexts. Survival processing may also affect metacognitive processes, by increasing confidence judgments as well as increasing metacognitive sensitivity. No previous study, however, has directly examined whether processing information for survival also has an effect on metacognitive processes. Here we ask whether SPE extends to the metacognitive system in terms of both metacognitive sensitivity and confidence bias. In Experiment 1 participants were asked to rate a list of words in terms of relevance in a survival scenario or a moving scenario. In a surprise old/new recognition test, they were given one word at a time and asked to indicate if they have rated the presented word before and state how confident they are in that choice. Surprisingly, the results did not reveal a SPE, which may have been due to high overall performance in the recognition task. In Experiment 2 we increased the level of difficulty of the memory task, which resulted in a robust SPE, but could not find this effect in metacognitive monitoring. Together, these results suggest that survival processing may not affect metacognitive processes in a reliable fashion.

Thinking of death and remembering living things: mortality salience and the animacy effect

The animacy effect, the finding that animate items are better remembered than inanimate items, provides evidence that human memory prioritizes information that is related to survival. Various proximate mechanisms for this memory effect have been proposed, including mortality salience, that humans are more likely to remember information related to death, and animate items (e.g., shark, tiger) are more likely to elicit thoughts of death than inanimate items (e.g., volleyball, towel). Mortality salience was manipulated in Experiment 1. Animate items were recalled more than inanimate items and threatening items were recalled more than nonthreatening items, but there was no significant effect of mortality salience. For Experiment 2, norming data were collected rating the word stimuli from the previous experiment on the characteristics of arousal, valence, likelihood to capture attention, and likelihood to elicit thoughts of death. These ratings along with threat ratings and animacy status of the items were included in a regression analysis with the frequency of recall of the items in Experiment 1. In addition to animacy, likelihood to capture attention and likelihood to elicit thoughts of death were significant predictors of recall, suggesting that these characteristics could be at least partly responsible for the animacy effect.

Adaptive memory: Animacy, threat, and attention in free recall

Animate items are better remembered than inanimate items, suggesting that human memory systems evolved in a way to prioritize memory for animacy. The proximate mechanisms responsible for the animacy effect are not yet known, but several possibilities have been suggested in previous research, including attention capture, mortality salience, and mental arousal (Popp & Serra in Journal of Experimental Psychology: Learning, Memory, and Cognition, 42, 186-201, 2016). Perceived threat of items could be related to any of these three potential proximate mechanisms. Because the characteristic of animacy is sometimes confounded with the perceived threat of the animate items, and because threatening items are often more likely to capture attention (e.g., Blanchette in The Quarterly Journal of Experimental Psychology, 59, 1484-1504, 2006), a norming study was first conducted to aid in the creation of lists of threatening and non-threatening animate and inanimate items. Two experiments were then conducted to determine if the animacy effect persisted regardless of the threat level of the items. The first experiment demonstrated the typical animacy advantage as well as a memory advantage for threatening items. The second experiment replicated these results across three successive recall tests as well as in both full attention and divided attention conditions. The results are discussed with respect to the potential proximate mechanisms of attention capture, mortality salience, and mental arousal.

Both the Survival Scenario and the Death Scenario Improve Memory Recall Regardless of the Processing/Priming Paradigm

Memory researchers have suggested human's memory system can help us remember adaptive information conducive to survival and avoiding death. However, in previous studies, the “survival-” orienting task and the “death-” orienting task were adopted in different paradigms. Specifically, the survival-related task was adopted in a processing paradigm, in which participants were instructed to process words in terms of its relevance of survival value, while the death-related task was adopted in a priming paradigm, in which participants were first placed in a death-salient state, and then rated the pleasantness of each word without encoding its death value. The current study aimed to explore whether death scenarios improve recall as much as survival scenarios regardless of the processing/priming paradigm. In Experiment 1, we compared a survival scenario, a death scenario and a control scenario in both processing and priming paradigms. Our results showed that: (a) both survival-related thoughts and death-related thoughts could improve memory recall, both in processing and in priming paradigms; and (b) participants' proportion of correct recall did not show difference between the survival and the death conditions. In Experiment 2, we used a more detailed control scenario and showed that both the death scenario and the survival scenario yielded higher recall than the control scenario in the priming paradigm. Together, our results suggest that both survival and death scenarios have a similar effect on memory recall regardless of the processing/priming paradigms.

Are animacy effects in episodic memory independent of encoding instructions?

The adaptive view of human memory [Nairne, J. S. 2010. Adaptive memory: Evolutionary constraints on remembering. In B. H. Ross (Ed.), The psychology of learning and motivation (Vol. 53 pp. 1-32). Burlington: Academic Press; Nairne, J. S., & Pandeirada, J. N. S. 2010a. Adaptive memory: Ancestral priorities and the mnemonic value of survival processing. Cognitive Psychology, 61, 1-22, 2010b; Memory functions. In The Corsini encyclopedia of psychology and behavioral science, (Vol 3, 4th ed. pp. 977-979). Hokoben, NJ: John Wiley & Sons] assumes that animates (e.g., baby, rabbit presented as words or pictures) are better remembered than inanimates (e.g., bottle, mountain) because animates are more important for fitness than inanimates. In four studies, we investigated whether the animacy effect in episodic memory (i.e., the better remembering of animates over inanimates) is independent of encoding instructions. Using both a factorial (Studies 1 and 3) and a multiple regression approach (Study 2), three studies tested whether certain contexts drive people to attend to inanimate more than to animate things (or the reverse), and therefore lead to differential animacy effects. The findings showed that animacy effects on recall performance were observed in the grassland-survival scenario used by Nairne, Thompson, and Pandeirada (2007. Adaptive memory: Survival processing enhances retention. Journal of Experimental Psychology: Learning, Memory, & Cognition, 33, 263-273) (Studies 1-3), when words were rated for their pleasantness (Study 2), and in explicit learning (Study 3). In the non-survival scenario of moving to a foreign land (Studies 1-2), animacy effects on recall rates were not reliable in Study 1, but were significant in Study 2, whereas these effects were reliable in the non-survival scenario of planning a trip as a tour guide (Study 3). A final (control) study (Study 4) was conducted to test specifically whether animacy effects are related to the more organised nature of animates than inanimates. Overall, the findings suggest that animacy effects are robust since they do not vary across different sets of encoding instructions (e.g., encoding for survival, preparing a trip and pleasantness).