Cross-Cultural Measurement Invariance in the Personality Inventory for DSM-5: Examination in several cultural environments or countries

Cross-Cultural Measurement Invariance in the Personality Inventory for DSM-5. M.A. Sorrel et al. Psychiatry Research, July 22 2021, 114134. https://doi.org/10.1016/j.psychres.2021.114134

Highlights

• It is again evidenced that the loading structure of the PID-5 is very complex

• Partial scalar invariance was supported which allowed for factor means comparisons

• The domain where the differences were greatest was psychoticism

• The influence of non-invariant items found to be was minimal

Abstract: The validity of cross-cultural comparisons of test scores requires that scores have the same meaning across cultures, which is usually tested by checking the invariance of the measurement model across groups. In the last decade, a large number of studies were conducted to verify the equivalence across cultures of the dimensional Alternative Model of Personality Disorders (DSM-5 Section III). These studies have provided information on configural invariance (i.e., the facets that compose the domains are the same) and metric invariance (i.e., facet-domain relationships are equal across groups), but not on the stricter scalar invariance (i.e., the baseline levels of the facets are the same), which is a prerequisite for meaningfully comparing group means. The present study aims to address this gap. The Personality Inventory for DSM-5 (PID-5) was administered to five samples differing on country and language (Belgium, Catalonia, France, Spain, and Switzerland), with a total of 4,380 participants. Configural and metric invariance were supported, denoting that the model structure was stable across samples. Partial scalar invariance was supported, being minimal the influence of non-invariant facets. This allowed cross-cultural mean comparisons. Results are discussed in light of the sample composition and a possible impact of culture on development of psychopathology.

Keywords: personality disordersDSM-5PID-5factor analysismeasurement invariance

3. Discussion

The present study provides evidence for the measurement invariance of the PID-5 across the cultures examined. This pattern concurs with Thimm et al. (2016)’s results which indicated that the scale was also invariant across United States and Norwegian samples. Since Thimm et al. analyzed university students only, they claimed that a more heterogeneous sample with a larger variety of age, educational level, and socioeconomic status should be analyzed in the future to test the cross-cultural stability of the structure of PID-5. Although university students were also analyzed in the present study, two samples came from the general population. Considering that findings from the present paper are more generalizable, the limitation of the composition of the sample is somewhat surpassed. Note also that no sharp differences in the structure were found between university (French-speaking samples) and community samples (Spanish and Catalonian samples). As in Thimm et al.’s study, some intercepts had to be released. These results imply that if different groups are to be compared, the more appropriate approach would be comparing the latent factor means. However, as the practical influence of the non-invariant items was shown to be minimal, observed scores might be also interpreted with caution. This adds to previous evidence showing that PID-5 domain scores can also be compared by sex and clinical status (Bach et al., 2017; Suzuki et al., 2019).

3.1. What could Explain the Differences in Intercepts and Means?

Differences in the intercepts and the latent means can be caused by two reasons. The first one would be variations on the sample composition. Note that samples from the community settings (Spanish and Catalonian ones) generally presented the lowest mean differences, and that some of the two largest differences were observed between the French and Belgium (university setting) and both Spanish and Catalonian samples for the Disinhibition domain. Besides, there were large differences in the age distribution. French-speaking samples were younger than the Spanish and Catalonian ones. It is a well-established fact that age has an impact on Disinhibition and related constructs as Sensation seeking (Steinberg et al., 2008), with younger subjects showing higher levels of Disinhibition (Zuckerman, 1994). That would be against other authors like Debast et al. (2018) who state that PID-5 is mostly age neutral. Samples also differed in terms of sex distribution with French-Speaking samples being composed mostly by females, and Spanish and Catalonian samples showing a more balanced distribution. Since women score higher on Neuroticism (Costa et al., 2001) and lower on Disinhibition and Sensation Seeking (Zuckerman, 1994), differences between all French-Speaking samples and Spain and Catalonian can be expected on these two domains. This pattern was observed for the comparisons with Belgium and France, but not with Switzerland. Besides, the previous study by Suzuki et al. (2019) explicitly examined the issue of gender invariance measurement for PID-5, finding that the scale was equivalent across sex. In summary, there is some room to support the hypothesis that the differences in the means may be due to variations in sample composition.

The second explanation of the differences across samples implies the presence of a real impact of the culture in the development of psychopathology. From this standpoint, culture may play a role in determining the exact behavioral and contextual formulation of some maladaptive behaviors and psychopathological manifestations (Terracciano & McCrae, 2006). The fact that differences on factor means were not homogeneous across samples with a similar composition (French-Speaking university samples), and that the samples from the same country (Spain) were generally similar in their latent means, suggests that culture may play a relevant role to explain differences on personality disorders. The five samples came from four different countries (i.e., Belgium, France, Spain, and Switzerland). The most widespread framework for comparing cultures is the six-dimensional classification generated by Hofstede (e.g., Hofstede, 2011). This model postulates six dimensions: power distance, uncertainty avoidance, masculinity vs. femininity, long term vs. short term orientation, and individualism vs. collectivism. Arguably, this last dimension has received the most attention in previous personality literature (e.g., Mulder, 2012; Triandis, 2001). According to Hofstede Insights dataset (Hofstede, 2018), Belgium, France, and Switzerland score similarly in the Individualism-collectivism dimension (75, 71, and 68, respectively), while the score for Spain is markedly lower (51). It has been suggested that a possible consequence of the individualistic culture on personality is to encourage the development of distinct/unique attitudes, self-definition, and striving to attain personal goals (Mulder, 2012). This is somewhat congruent with the fact that France obtained the highest mean in Disinhibition and Spain the lowest. The existence of cohort effects is often cited as an argument for the influence of social and cultural factors on personality. For example, the antisocial behavior profile maintains an upward trend and has doubled in value since World War II (Kessler et al., 1994). However, it should be recalled here that studies linking culture and personality are still scarce, so that the hypotheses put forward should be taken with caution.

3.2. Concluding Remarks on the PID-5 Factor Loading Structure

The loading solution was very similar to that reported by the two available meta-analyses (Somma et al., 2019; Watters and Bagby, 2018). It is again evidenced that the factorial structure of PID-5 is complex, with multiple cross loadings. Specifically, 30 out of 100 possible secondary loadings had a factor loading greater than .20 in absolute value. Only 8 out of the 25 facets (32%) did not present any secondary loading greater than .20 in absolute value (i.e., Emotional lability, Separation insecurity, Submissiveness, Withdrawal, Intimacy avoidance, Manipulativeness, Irresponsibility, and Unusual beliefs and experiences). The most complex facets were Rigid perfectionism and Risk taking. This complex structure might have serious implications for assessment utility (discriminant validity) and theory (Crego et al., 2015; Watters et al., 2018). While some of these secondary loadings can be supported from a theoretical standpoint (e.g., Risk-taking has been related to Negative Affect, Disinhibition and Antisocial behaviour patterns; Aluja et al., 2007), in general, it draws attention to the fact that a revision of the instrument would probably be necessary to reach the most discriminant structure with theoretical meaning.

3.3. Limitations and Future Directions

The present work is not without limitations. The reported fit values are adequate considering previous literature on the PID-5, but again serve to illustrate that it is difficult to obtain excellent fit values when exploring factor structure in the areas of personality and personality disorders. Authors such as Hopwood and Donnellan (2010) have argued that it is to be expected that it would not be easy to achieve excellent model-data fit, given how easy it is to find items with similar phrasing or other methodology artifacts (e.g., acquiescence). It is expected that modelling these factors will lead to a better fit (Abad et al., 2018). Yet, it is important to remember that this is one of the sources of validity evidence available to support the interpretation and use of the scale scores. The fact that adequate evidence of criterion-referenced validity for the PID-5 scores is reported in prior research also contributes to that purpose (Al-Dajani et al., 2016). As for the analysed samples, all of them came from European Western cultures. In the personality field, Allik et al. (2017) and Aluja et al. (2020) found that similar cultures seem to have similar mean personality profiles. The present study supports this idea also would apply in the context of pathological personality, as most of the effect sizes of differences between countries did not reach a medium effect size, and latent means for Spanish and Catalonian samples were generally similar. It is possible that incorporating non-European Western cultures could change this pattern of cross-cultural stability of the structure, although some other studies suggest a stability beyond western cultures (Rossier et al., 2008). Another limitation is that the current study used only a nonclinical sample. However, the available research seems to indicate that this is not a major concern since prior studies found that the results at the domain level obtained in non-clinical samples might be generalized to clinical populations (Bach et al., 2018).

Putting the cart before the horse: claims for mirror self-recognition in horses are unfounded

Putting the cart before the horse: claims for mirror self-recognition in horses are unfounded. Gordon G. Gallup Jr. & James R. Anderson. Animal Cognition, Jul 27 2021. https://rd.springer.com/article/10.1007/s10071-021-01538-9

Abstract: The recent article by Baragli, Scopa, Maglieri, and Palagi (Anim Cogn https://doi.org/10.1007/s10071-021-01502-7, 2021) that claims to demonstrate mirror self-recognition (MSR) in horses is not based on compelling evidence. We identify problems with their experimental procedures, data, and assertion about “demonstrating MSR at group level.” Examples of these problems include incomplete experimental design, absence of important control conditions, inappropriate terminology, suboptimal mark application procedures and coding of videos, ambiguity of videos presented as supporting evidence, and inconsistencies in data presentation and interpretation. It is not the case that their study “marks a turning point in the analytical technique of MSR exploration.”

Strangers Look Sicker (with Implications in Times of COVID-19)

Bressan, Paola. 2021. “Strangers Look Sicker (with Implications in Times of COVID-19).” PsyArXiv. July 26. doi:10.1002/bies.202000158

Abstract: We animals have evolved a variety of mechanisms to avoid conspecifics who might be infected. It is currently unclear whether and why this “behavioral immune system” targets unfamiliar individuals more than familiar ones. Here I answer this question in humans, using publicly available data of a recent study on 1969 participants from India and 1615 from the USA. The apparent health of a male stranger, as estimated from his face, and the comfort with contact with him were a direct function of his similarity to the men in the local community. This held true regardless of whether the face carried overt signs of infection. I conclude that our behavioral immune system is finely tuned to degrees of outgroupness—and that cues of outgroupness are partly processed as cues of infectiousness. These findings, which were consistent across the two cultures, support the notion that the pathogens of strangers are perceived as more dangerous.

Potential for Collaboration: Differences Between Evolutionary Anthropology and Evolutionary Psychology as Scientific Disciplines

Hahnel-Peeters, Rebecka K. 2021. “Potential for Collaboration: Differences Between Evolutionary Anthropology and Evolutionary Psychology as Scientific Disciplines.” PsyArXiv. July 20. doi:10.31234/osf.io/kp4rc

Abstract: In a review of evolutionary analysis of human behavior, Alden Smith (2000) argues that evolutionary anthropology and evolutionary psychology should not be considered competing disciplines. If evolutionary anthropology and psychology were to become more collaborative, it would aid our understanding of human nature – regardless of the different assumptions and empirical methodology used by the two disciplines. The recent 10th anniversary of “The WEIRDEST people in the world” (Henrich et al, 2010) presents a good opportunity to assess the current state of the evolutionary social sciences. While scholars (e.g., Barrett, 2020) have provided thoughts on the future direction of the evolutionary social sciences, none have explicitly evaluated the degree to which the various subdisciplines within the evolutionary social sciences have moved toward greater collaboration over the past decade. The current study uses content analysis to systematically examine if the disciplines of evolutionary anthropology and psychology are becoming more collaborative by reporting the frequency of coauthored peer-reviewed papers published in Evolution and Human Behavior (EHB), the type of data, and the empirical methodology used in these papers. A total of 737 articles published in EHB between 2009 and 2020 were coded, and no evidence of increased frequency of anthropologist and psychologist collaborations was found. While evolutionary anthropologists and psychologists did not report different types of data or topics of interest, the methods for hypothesis testing were different. I discuss limitations for the current content analysis and review suggested future steps for unification.

Domestic cats (Felis catus) prefer freely available food over food that requires the slightest effort

Domestic cats (Felis catus) prefer freely available food over food that requires effort. Mikel M. Delgado, Brandon Sang Gyuc Han & Melissa J. Bain. Animal Cognition, Jul 26 2021. https://rd.springer.com/article/10.1007/s10071-021-01530-3

Abstract: Contrafreeloading is the willingness of animals to work for food when equivalent food is freely available. This behavior is observed in laboratory, domesticated, and captive animals. However, previous research found that six laboratory cats failed to contrafreeload. We hypothesized that cats would contrafreeload in the home environment when given a choice between a food puzzle and a tray of similar size and shape. We also hypothesized that more active cats would be more likely to contrafreeload. We assessed the behavior of 17 neutered, indoor domestic cats (Felis catus) when presented with both a food puzzle and a tray across ten 30-min trials. Each cat wore an activity tracker, and all sessions were video recorded. Cats ate more food from the free feed tray than the puzzle (t (16) = 6.77, p < 0.001). Cats made more first choices to approach and eat from the tray. There was no relationship between activity and contrafreeloading, and there was no effect of sex, age, or previous food puzzle experience on contrafreeloading. Our results suggest that cats do not show strong tendencies to contrafreeload in the home environment, although some cats (N = 4) ate most food offered in the puzzle or showed weak contrafreeloading tendencies (N = 5). Eight cats did not contrafreeload. Cats who consumed more food from the puzzle, consumed more food in general, suggesting a relationship between hunger and effort. Further research is required to understand why domestic cats, unlike other tested species, do not show a strong preference to work for food.

Discussion

In this study, we tested for the first time whether domestic cats living in homes would contrafreeload, as has been demonstrated in several captive and domesticated species. We did not find strong evidence for contrafreeloading; instead, cats preferred to eat the food that was freely available with no required additional effort. This was true when looking at both the overall population of cats, and the behavior of individual cats across trials.

We were unable to identify specific individual traits (sex, age and previous experience with a food puzzle) that predicted whether cats would contrafreeload. The four cats who appeared to be contrafreeloaders had one trait in common; they ate most of the food available to them during trials. In fact, the strongest predictor of amount of food eaten from the puzzle was the amount of food eaten from the tray.

The unanswered question is why cats, among multiple species tested, appear to be the only one that does not reliably contrafreeload. This tendency appears to contradict the fact that cats naturally work for food by hunting and will stop eating to hunt additional prey (Adamec 1976; Leyhausen 1979). Some differences in contrafreeloading tendencies among species have been attributed to domestication, such as in one study where white leghorn layers contrafreeloaded less than their ancestral species, jungle fowl (Jensen et al. 2002). Possible explanations included selection for allocation of resources toward reproduction and individual growth, and less need for information gathering when food sources are stable.

The cats in our study were all spayed or neutered and housed indoors only, which might have impacted their behavior. Spaying and neutering decreases the metabolic rate (Fettman et al. 1997) and the physical activity of female cats (Belsito et al. 2009), while simultaneously increasing cats’ food intake (Alexander et al. 2011; Wei et al. 2014). However, the previous study that failed to find evidence of contrafreeloading in cats only included reproductively intact cats (Koffer and Coulson 1971). To date, no studies have directly compared the activity patterns of indoor cats with those who have outdoor access. Thus, it would be premature to predict different results from reproductively intact or outdoor cats.

We also found no relationship between activity and contrafreeloading behavior. This result supports a previous study that found no change in activity level after introducing food puzzles to cats (Naik et al. 2018). Another study found that when two laboratory cats were required to offer an increasing number of touches to a switchplate in exchange for free access to food, they decreased the number of meals per day, and consumed more food at each feeding period (Collier et al. 1997). Studies of free-roaming feral cats suggest they spend almost 90% of their time inactive, with < 1% of their time spent hunting (Hernandez et al. 2018). In general, cats appear to conserve energy to the greatest extent possible, minimizing the amount of time and effort required to meet their caloric requirements, whether by hunting or engaging with enrichment devices in homes.

Our conclusion that cats prefer freely available food over that which requires effort is limited by some aspects of our study, such as a relatively small sample size. It is possible that the appearance of the food puzzle hindered consumption, as food was more visible in the tray. However, the cover of the puzzle was translucent, and several of the compartments face upward, such that the food would be visible from above. Although the novelty or shape of the food puzzle could have been a deterrent to the cats, we controlled for this by presenting all cats with a novel tray of the same shape and size simultaneously. All cats ate from both the puzzle and the tray during the training period, so we do not believe that appearance, novelty, or aversion to the device itself can explain the failure to contrafreeload.

We also did not control for food intake or hunger, as we did not want to increase the stress levels of cats, who can be sensitive to changes in feeding regimens (Stella et al. 2011). Food restriction can also reduce contrafreeloading (Inglis et al. 1997), so we did not want food withheld from cats longer than they were accustomed to. Since the cats ate a large percentage of the freely available food during trials, we cannot blame the failure to contrafreeload on a lack of interest in food. However, as we only gave cats access to the tray and puzzle for 30 min per trial, it is possible that cats would have engaged more with the puzzle if it continued to be available throughout the day.

Interpretation of our results may be dependent on how contrafreeloading is defined. Sometimes contrafreeloading is defined as when an animal will work for any food in the presence of freely available food, whereas some consider it a preference to work for food (Inglis et al., Osborne et al.). Most cats in our study did eat some food from the puzzle but none ate more food from the puzzle than the tray. Thus, although we have evidence for some willingness to work for food when freely available food is present (weak contrafreeloading), there is no evidence that cats preferred to work for food.

Of the species who have been tested for contrafreeloading, few predatory species (chimps, humans, and cats) are included, and most species tested are foragers who use extended search to acquire food (e.g., pigeons, rats, gerbils, Inglis et al. 1997). Sit-and-wait predation is considered low cost and is a common hunting style among felids (Williams et al. 2014). A full discussion of predatory energetics is beyond the scope of this manuscript, but contrafreeloading, which provides information about the quality of food patches, is expected to be weaker in species that do not engage in prolonged search (Inglis et al. 1997). Future studies should investigate whether foraging style is an important factor in contrafreeloading tendencies, and whether energy conservation is influential.

Like other studies, we did not find a statistically significant effect of sex on contrafreeloading (Lindqvist and Jensen 2008; Vasconcellos et al. 2012). However, in the current study, the four cats who did show a tendency to contrafreeload were all males, and the two cats who did not eat any food from the puzzle were both females. Male cats are more prone to obesity (Lund et al. 2005) and may be more food motivated in general. Our findings suggest the sex of the cat should be considered in future studies.

Future research can further explore contrafreeloading in cats by introducing different types of food puzzles or operant behaviors necessary for obtaining food. Changing the value of the food offered may also increase contrafreeloading, as novelty of food items increases the level of reinforcement (Inglis et al. 1997). The effects of foraging enrichment on cat welfare and health indicators should also be assessed. A presentation of case studies found positive effects of food puzzles for domestic cats, such as weight reduction and an improvement of behavioral health (Dantas et al. 2016), but puzzles do not appear to increase overall activity levels (Naik et al. 2018).

Understanding contrafreeloading is important for captive and domestic animal welfare as foraging enrichment is a frequently used tool to provide choice and mental stimulation. The effects of such enrichment on the behavior of captive animals are rarely tested. For domestic cats, the provision of foraging enrichment may depend on the needs and food motivation of the individual animal, and may be best introduced as a choice to enhance welfare, as foraging enrichment has been suggested to do in other species (e.g., Tarou and Bashaw 2007).

Changes in Atlantic major hurricane frequency since the late-19th century

Changes in Atlantic major hurricane frequency since the late-19th century. Gabriel A. Vecchi, Christopher Landsea, Wei Zhang, Gabriele Villarini & Thomas Knutson. Nature Communications volume 12, Article number: 4054. Jul 19 2021. https://www.nature.com/articles/s41467-021-24268-5

Abstract: Atlantic hurricanes are a major hazard to life and property, and a topic of intense scientific interest. Historical changes in observing practices limit the utility of century-scale records of Atlantic major hurricane frequency. To evaluate past changes in frequency, we have here developed a homogenization method for Atlantic hurricane and major hurricane frequency over 1851–2019. We find that recorded century-scale increases in Atlantic hurricane and major hurricane frequency, and associated decrease in USA hurricanes strike fraction, are consistent with changes in observing practices and not likely a true climate trend. After homogenization, increases in basin-wide hurricane and major hurricane activity since the 1970s are not part of a century-scale increase, but a recovery from a deep minimum in the 1960s–1980s. We suggest internal (e.g., Atlantic multidecadal) climate variability and aerosol-induced mid-to-late-20th century major hurricane frequency reductions have probably masked century-scale greenhouse-gas warming contributions to North Atlantic major hurricane frequency.

Discussion

One of the most consistent expectations from projected future global warming is that there should be an increase in TC intensity, such that the fraction of MH to HU increases6,20,21,22,25,26,27,28,29,30,31. This issue has become more pressing with the recent finding of a global increase in this metric since 1979 using homogenized satellite-based data14—a finding to which Atlantic HU contribute. We here build on the methods of refs. 9,10 to build a homogenized record of Atlantic MH frequency and MH/HU ratio since the 19th century. We find here that, once we include a correction for undercounts in the pre-satellite era basin-wide NA HU and MH frequency, there are no significant increases in either basin-wide HU or MH frequency, or in the MH/HU ratio for the Atlantic basin between 1878 and 2019 (when the U.S. Signal Corps started tracking NA HUs35). We suggest that the modestly significant 1851–2019 increase in basin-wide MH frequency and MH/HU ratio that remains after including the HU and MH adjustment reflects data inhomogeneity that our adjustment is unable to correct—rather than an actual increase in these quantities. The homogenized basin-wide HU and MH record does not show strong evidence of a century-scale increase in either MH frequency or MH/HU ratio associated with the century-scale, greenhouse-gas-induced warming of the planet. For example, the temporal evolution of the global mean temperature is not closely reflected in the temporal evolution of adjusted MH/HU ratio shown in Fig. 4.

Does this work provide evidence against the hypothesis that greenhouse-gas-induced warming may lead to an intensification of North Atlantic HUs? Not necessarily. Substantial multi-decadal variability may obscure trends computed over the past century16,17,18,20,21, and recent studies suggest the possibility for an aerosol-driven reduction in NA HU and MH activity over the 1960s–1980s (refs. 19,20,21,22,23,24), which may have obscured any greenhouse induced NA HU and MH intensification over the 20th century. For example, a statistical downscaling of global climate models (GCMs) that were part of the Coupled Model Intercomparison Project Phase 5 (CMIP5) shows a robust and significant projection for a greenhouse gas-induced 21st century NA hurricane intensification; yet applying that same method to historical simulations the greenhouse-induced intensification over the late-19th and 20th century is masked by the late-20th century aerosol-induced weakening20. Historical simulations show that aerosol forcing may have masked the 19th-20th century greenhouse-gas-induced increase in potential intensity, the theoretical upper bound on tropical cyclone intensity, even though climate models show increases in potential intensity in tropical cyclone regions in response to projected future warming24,25,26. The homogenized MH and HU data developed in the present study serve as a target for century-scale historical simulations with high-resolution dynamical and statistical models that are used for 21st century projections.

The adjusted NA basin-wide MH frequency and MH/HU ratio show substantial multi-decadal variability (Figs. 2, 4), and the adjusted basin-wide MH frequency shows its lowest values over the 1960s–1980s (Fig. 2). These features show at least qualitative consistency with the notion of a strong influence of either internal multi-decadal climate variability and/or late-20th century aerosol-induced weakening of NA HU intensity during that period. Our homogenized records also correspond with document- and proxy-based reconstructions of Antilles and Atlantic HUs, which indicate that substantial variability in HU frequency has been present in the Atlantic, and the inactive period in the late 20th century may have been the most inactive period in recent centuries42,43.

The homogenized hurricane records suggest a consistent and marginally statistically significant decrease in the ratio of basin-wide hurricanes striking the USA as hurricanes (Table 2, row 3). Some models project an eastward shift in the location of NA TCs in response to increasing greenhouse gases (e.g., refs. 27,28), so this observed change may reflect the emerging impact of greenhouse warming on NA TC tracks. However, although there is a nominal decrease in the ratio of basin-wide MH striking the USA as MH (Table 2, row 4), the trends are not significant for any of the time periods explored.

Caution should be taken in connecting recent changes in Atlantic hurricane activity to the century-scale warming of our planet. The adjusted records presented here provide a century-scale context with which to interpret recent studies indicating a significant recent increase in NA MH/HU ratio over 1980–2017 (ref. 14), or in the fraction of NA tropical storms that rapidly intensified over 1982–2009 (ref. 15). Our results indicate that the recent increase in NA basin-wide MH/HU ratio or MH frequency is not part of a century-scale increase. Rather it is a rebound from a deep local minimum in the 1960s–1980s. We hypothesize that these recent increases contain a substantial, even dominant, contribution from internal climate variability16,17,18,20,21, and/or late-20th century aerosol increases and subsequent decreases19,20,21,22,23,24, in addition to any contributions from recent greenhouse gas-induced warming20,22,24,44. It has been hypothesized, for example, that aerosol-induced reductions in surface insolation over the tropical Atlantic since between the mid-20th century and the 1980s may have resulted in an inhibition of tropical cyclone activity19,20,21,22,23,24; the relative contributions of anthropogenic sulfate aerosols, dust, and volcanic aerosols to this signal (each of which would carry distinct implications for future hurricane evolution)—along with the magnitude and impact of aerosol-mediated cloud changes—remain a vigorous topic of scientific inquiry. It has also been suggested that multi-decadal climate variations connected to changes in meridional ocean overturning may have resulted in a minimum in northward heat transport in the Atlantic and a resulting reduction in Atlantic hurricane activity16,17,18,20,21. Given the uncertainties that presently exist in understanding multi-decadal climate variability, the climate response to aerosols and impact of greenhouse gas warming on NA TC activity, care must be exercised in not over-interpreting the implications of, and causes behind, these recent NA MH increases. Disentangling the relative impact of multiple climate drivers on NA MH activity is crucial to building a more confident assessment of the likely course of future HU activity in a world where the effects of greenhouse gas changes are expected to become increasingly important.