Continuous Environmental Changes May Enhance Topographic Memory Skills. Evidence From L'Aquila Earthquake-Exposed Survivors

Abstract

Exposure to environmental contextual changes, such as those occurring after an earthquake, requires individuals to learn novel routes around their environment, landmarks and spatial layout. In this study, we aimed to uncover whether contextual changes that occurred after the 2009 L'Aquila earthquake affected topographic memory in exposed survivors. We hypothesized that individuals exposed to environmental changes-individuals living in L'Aquila before, during and after the earthquake (hereafter called exposed participants, EPs)-improved their topographic memory skills compared with non-exposed participants (NEPs) who moved to L'Aquila after the earthquake, as only EPs had to modify their previous cognitive map of L'Aquila. We also hypothesized that memory improvement was selective for the navigational space and did not generalize across other spatial and verbal domains. To test these hypotheses, we compared the topographic and spatial memory skills of 56 EPs without post-traumatic stress disorder (PTSD) symptoms to the skills of 47 NEPs using the Walking Corsi Test (WalCT; memory test in the navigational space) and the Corsi Block-Tapping Test (CBT; visuospatial memory test in the reaching space); EPs and NEPs were matched for gender, education and general navigational skills. A sub-group of participants also underwent the Rey-Auditory Verbal Learning Test (RAVLT; verbal memory test). The results showed that only EPs had better performances on topographic learning (TL) assessed using the WalCT rather than spatial learning assessed by the CBT. This outcome suggests the possibility that EPs specifically improved topographic memory. This effect may be due to continuous exposure to environmental changes that have required individuals to learn novel paths within the city and integrate novel information, such as "new towns," into their pre-existing mental representation of the city. Implications and limitations of the study are discussed.

Keywords: adaptation mechanisms; earthquakes; human navigation; natural disasters; post-traumatic stress; spatial orientation; topographical learning; trauma-induced sequelae.

Figure 1

City map of L’Aquila before and after the earthquake. The figure shows the deep, urban modifications that inevitably forced citizens to re-learn the paths of their city after the earthquake. The background map shows: 1) the city center (the red circle; 2) suburbs, where the “new towns” (depicted in black on the map) were built for citizens whose houses were destroyed during the earthquake. The map was derived from the website of the Italian Civil Protection (decree n. 6, 11 May 2009. Source: http://www.protezionecivile.gov.it/jcms/it/view_dossier.wp;jsessionid=162AA553223F304BCBBADDF517785517?contentId=DOS282). On the top right panel of the figure, the map focuses on the changes of L’Aquila city center. Here, a typical route between a starting (S) and an ending (E) point is depicted as it appeared before (blue line) and after (yellow line) the earthquake. The path from S to E was quite short before the earthquake (approximately 0.6 km). However, due to the presence of blocked routes, going from S to E after the earthquake required a very long path (approximately 3.4 km). The map was created using Google Earth^© 2018 and Google Maps^© 2018. After the earthquake, landmarks along the route dramatically changed. Examples are provided in the a–c boxes (a the bridge “ponte Bel Vedere”; b the students’ dormitory; c the “Duca degli Abruzzi” hotel). The three white stars indicate their positions on the map.

Figure 2

(A) The Walking Corsi Test (WalCT): examiner and participant while performing the task. Written informed consent was obtained from the subjects represented in the figure for publication of this experiment. A copy of the written consent is available for review by the Editor-in-Chief of this journal. (B) The Corsi Block-Tapping Test (CBT) apparatus.