Causal inference in ethnographic research: Refining explanations with abductive logic, strength of evidence assessments, and graphical models

In their classic accounts, anthropological ethnographers developed causal arguments for how specific sociocultural structures and processes shaped human thought, behavior, and experience in particular settings. Despite this history, many contemporary ethnographers avoid establishing in their work direct causal relationships between key variables in the way that, for example, quantitative research relying on experimental or longitudinal data might. As a result, ethnographers in anthropology and other fields have not advanced understandings of how to derive causal explanations from their data, which contrasts with a vibrant "causal revolution" unfolding in the broader social and behavioral sciences. Given this gap in understanding, we aim in the current article to clarify the potential ethnography has for illuminating causal processes related to the cultural influence on human knowledge and practice. We do so by drawing on our ongoing mixed methods ethnographic study of games, play, and avatar identities. In our ethnographic illustrations, we clarify points often left unsaid in both classic anthropological ethnographies and in more contemporary interdisciplinary theorizing on qualitative research methodologies. More specifically, we argue that for ethnographic studies to illuminate causal processes, it is helpful, first, to state the implicit strengths and logic of ethnography and, second, to connect ethnographic practice more fully to now well-developed interdisciplinary approaches to causal inference. In relation to the first point, we highlight the abductive inferential logic of ethnography. Regarding the second point, we connect the ethnographic logic of abduction to what Judea Pearl has called the ladder of causality, where moving from association to intervention to what he calls counterfactual reasoning produces stronger evidence for causal processes. Further, we show how graphical modeling approaches to causal explanation can help ethnographers clarify their thinking. Overall, we offer an alternative vision of ethnography, which contrasts, but nevertheless remains consistent with, currently more dominant interpretive approaches.

Social connection and gene regulation during the COVID-19 pandemic: Divergent patterns for online and in-person interaction

BACKGROUND

Social connection has been linked to reduced disease risk and enhanced antiviral immunity, but it is unclear whether online social connections have similar effects to those previously documented for in-person/offline social relationships, or whether online connections can substitute for in-person social relations when the latter are restricted. We examined this question in the context of the COVID-19 pandemic, focusing specifically on an immune system gene regulation profile known as the conserved transcriptional response to adversity (CTRA), which is characterized by up-regulation of proinflammatory genes and down-regulation of genes linked to innate antiviral responses and antibody production.

METHODS

We analyzed CTRA RNA profiles in blood samples from 142 healthy young adults (69% female, 87% white) during the "social distancing" period of the COVID-19 pandemic. Mixed effect linear models quantified the relation of CTRA gene expression to measures of in-person social connection (number of friends, social eudaimonia, loneliness) and online psychosocial connection (online loneliness, perceived social value in online leisure and educational contexts, and internet use) while controlling for demographic and health factors.

RESULTS

Multiple indicators of in-person and generalized social connection were associated with lower CTRA gene expression, whereas no measure of online social connection showed any significant association with CTRA gene expression.

CONCLUSION

Experiences of in-person social connection are associated with reduced CTRA gene expression during a period of restricted social interaction. In contrast, online social relationships show no such association. Digitally mediated social relations do not appear to substantially offset the absence of in-person/offline social connection in the context of immune cell gene regulation.

Internet gaming, embodied distress, and psychosocial well-being: A syndemic-syndaimonic continuum

We examine internet gaming-related suffering as a novel syndemic most prevalent among contemporary emerging adults. Synthetic analysis of our prior research on internet gaming and health affirms how social factors and mental and physical wellness mutually condition each other in this online play context. Employing biocultural anthropological mixed methods, we focus on statistical interactions between intensive gaming and social well-being in relation to genomic markers of immune function. We show that among gamers with low social well-being, intensive game play is associated with compromised immunity markers, but among those with robust social connection, that same play correlates with decreased activation of stress-related immunity activation. The apparently beneficial interaction of higher social well-being and intensive game play resonates with an emerging body of research showing how positive practices-in this case, engaged and pleasurable videogame play-can increase resilience to the negative linked psychological and genomic responses to precarity. Based on these findings, we argue, in relation to gaming behaviors, a syndemics analysis could usefully be expanded by attending to both sides of the synergistic interaction between two social conditions: not just exacerbation of dysfunction in relation to their combined effect, but also non-additive enhancement of health that may stem from such combinations. We draw on literature emphasizing the relevance to health of "eudaimonic" well-being-psychosocial processes that transcend immediate self-gratification and involve the pursuit of meaningful and pro-social goals. On that basis, we propose the term "syndaimonics" to capture synergies between social context and mental flourishing, which, in this context and presumably others, can illuminate sources of health resilience and overall improved psychosocial wellbeing.

Avatar Creation in Videogaming: Between Compensation and Constraint

Objective: We examine the extent that videogame avatars provide players with opportunities for identity exploration, aiming to test the findings of self-discrepancy theory research on the user/avatar relationship with novel cognitive anthropological methods. Specifically, we examine if avatar traits are idealized (more representative of players' ideal rather than actual self) or actualized (more representative of players' actual self) as a function of players' self-esteem. Materials and Methods: Utilizing cognitive anthropological methods, we examine the relationship between actual, avatar, and ideal selves. We first asked 21 respondents to list traits they associated with their various selves. We then asked 57 new respondents to perform four pile sorts of the salient items from these lists (1 unconstrained sort of like-traits, and 3 sorts of terms indicative of respondents' ideal/actual/avatar self). Analysis of this "free list" and "pile sort" data allowed us to clarify (in a manner sensitive to gamer culture) relationships between respondents' various conceptions of self, including how those relationships were modified by self-esteem. Illustrative quotes from the interviews further clarified these relationships. Results: Paired t-test analysis shows that informants as a whole describe their avatar compared with actual selves with fewer negative terms (idealization). Low-esteem players actualize what they deem as positive traits onto their avatars, while simultaneously idealizing avatars' negative traits by minimizing them. Compared with low-esteem gamers, high-esteem players associate significantly more positive attributes with all their various selves-actual, avatar, and ideal-while describing avatar compared with actual selves with fewer positive terms and comparable numbers of negative terms (the latter a process of actualization). Conclusion: Results point to the necessity of theoretical accounts that recognize that avatars may reflect a complex relationship with the user's actual and ideal self, without assuming that avatar play frees gamers from offline social, psychological, or bodily constraints.

Positive mental well-being and immune transcriptional profiles in highly involved videogame players

Previous research has identified a link between experiencing life as meaningful and purposeful-what is referred to as "eudaimonia"-and reduced expression of a stress-induced gene profile known as the "conserved transcriptional response to adversity" (CTRA). In the current study, we examine whether similar links between eudaimonic well-being and CTRA reduction occur in a sample of 56 individuals with a particularly strong engagement with virtual worlds: avid online videogame players. Results consistently linked higher eudaimonic well-being, and more specifically the social well-being subdomain of eudaimonia, to lower levels of CTRA gene expression. That favorable psychobiological relationship between eudaimonia and CTRA appeared most strongly among individuals reporting high levels of positive psychosocial involvement with gaming. Findings are consistent with the hypothesis that committed social/recreational activity may help damp CTRA expression especially among persons who are already experiencing some kind of threshold of positive eudaimonic experience.

Intensive online videogame involvement: A new global idiom of wellness and distress

Extending classic anthropological "idioms of distress" research, we argue that intensive online videogame involvement is better conceptualized as a new global idiom, not only of distress but also of wellness, especially for emerging adults (late teens through the 20s). Drawing on cognitive anthropological cultural domain interviews conducted with a small sample of U.S. gamers (N = 26 free-list and 34 pile-sort respondents) (Study 1) and a large sample of survey data on gaming experience (N = 3629) (Study 2), we discuss the cultural meaning and social context of this new cultural idiom of wellness and distress. Our analysis suggests that the "addiction" frame provides a means for gamers to communicate their passion and commitment to online play, even furthering their enthusiasm for the hobby and community in the process, but also a way for players to express and even resolve life distress such as depression and loneliness. The American Psychiatric Association (APA) has recently included "Internet gaming disorder" (IGD) as a possible behavioral addiction, akin to gambling, warranting further consideration for eventual formal inclusion in the next iteration of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Our study leads us to suggest that clinicians only sparingly use IGD as a clinical category, given that medical and gamer understandings of "addictive" play differ so markedly. This includes better distinguishing positive online gaming involvement-also sometimes framed by gamers as "addictive"-from other play patterns more clearly entailing distress and dysfunction.

Social genomics of healthy and disordered internet gaming

OBJECTIVES

To combine social genomics with cultural approaches to expand understandings of the somatic health dynamics of online gaming, including in the controversial nosological construct of internet gaming disorder (IGD).

METHODS

In blood samples from 56 U.S. gamers, we examined expression of the conserved transcriptional response to adversity (CTRA), a leukocyte gene expression profile activated by chronic stress. We compared positively engaged and problem gamers, as identified by an ethnographically developed measure, the Positive and Negative Gaming Experiences Scale (PNGE-42), and also by a clinically derived IGD scale (IGDS-SF9).

RESULTS

CTRA profiles showed a clear relationship with PNGE-42, with a substantial linkage to offline social support, but were not meaningfully associated with disordered play as measured by IGDS-SF9.

CONCLUSIONS

Our study advances understanding of the psychobiology of play, demonstrating via novel transcriptomic methods the association of negatively experienced internet play with biological measures of chronic threat, uncertainty, and distress. Our findings are consistent with the view that problematic patterns of online gaming are a proxy for broader patterns of biopsychosocial stress and distress such as loneliness, rather than a psychiatric disorder sui generis, which might exist apart from gamers' other life problems. By confirming the biological correlates of certain patterns of internet gaming, culturally-sensitive genomics approaches such as this can inform both evolutionary theorizing regarding the nature of play, as well as current psychiatric debates about the appropriateness of modeling distressful gaming on substance addiction and problem gambling.

Stress and telomere shortening among central Indian conservation refugees

Research links psychosocial stress to premature telomere shortening and accelerated human aging; however, this association has only been demonstrated in so-called "WEIRD" societies (Western, educated, industrialized, rich, and democratic), where stress is typically lower and life expectancies longer. By contrast, we examine stress and telomere shortening in a non-Western setting among a highly stressed population with overall lower life expectancies: poor indigenous people--the Sahariya--who were displaced (between 1998 and 2002) from their ancestral homes in a central Indian wildlife sanctuary. In this setting, we examined adult populations in two representative villages, one relocated to accommodate the introduction of Asiatic lions into the sanctuary (n = 24 individuals), and the other newly isolated in the sanctuary buffer zone after their previous neighbors were moved (n = 22). Our research strategy combined physical stress measures via the salivary analytes cortisol and α-amylase with self-assessments of psychosomatic stress, ethnographic observations, and telomere length assessment [telomere-fluorescence in situ hybridization (TEL-FISH) coupled with 3D imaging of buccal cell nuclei], providing high-resolution data amenable to multilevel statistical analysis. Consistent with expectations, we found significant associations between each of our stress measures--the two salivary analytes and the psychosomatic symptom survey--and telomere length, after adjusting for relevant behavioral, health, and demographic traits. As the first study (to our knowledge) to link stress to telomere length in a non-WEIRD population, our research strengthens the case for stress-induced telomere shortening as a pancultural biomarker of compromised health and aging.

Maternal exposure to hurricane destruction and fetal mortality

BACKGROUND

The majority of research documenting the public health impacts of natural disasters focuses on the well-being of adults and their living children. Negative effects may also occur in the unborn, exposed to disaster stressors when critical organ systems are developing and when the consequences of exposure are large.

METHODS

We exploit spatial and temporal variation in hurricane behaviour as a quasi-experimental design to assess whether fetal death is dose-responsive in the extent of hurricane damage. Data on births and fetal deaths are merged with Parish-level housing wreckage data. Fetal outcomes are regressed on housing wreckage adjusting for the maternal, fetal, placental and other risk factors. The average causal effect of maternal exposure to hurricane destruction is captured by difference-in-differences analyses.

RESULTS

The adjusted odds of fetal death are 1.40 (1.07-1.83) and 2.37 (1.684-3.327) times higher in parishes suffering 10-50% and >50% wreckage to housing stock, respectively. For every 1% increase in the destruction of housing stock, we observe a 1.7% (1.1-2.4%) increase in fetal death. Of the 410 officially recorded fetal deaths in these parishes, between 117 and 205 may be attributable to hurricane destruction and postdisaster disorder. The estimated fetal death toll is 17.4-30.6% of the human death toll.

CONCLUSIONS

The destruction caused by Hurricanes Katrina and Rita imposed significant measurable losses in terms of fetal death. Postdisaster migratory dynamics suggest that the reported effects of maternal exposure to hurricane destruction on fetal death may be conservative.

Influence of aesthetic appreciation of wildlife species on attitudes towards their conservation in Kenyan agropastoralist communities

The influence of human aesthetic appreciation of animal species on public attitudes towards their conservation and related decision-making has been studied in industrialized countries but remains underexplored in developing countries. Working in three agropastoralist communities around Amboseli National Park, southern Kenya, we investigated the relative strength of human aesthetic appreciation on local attitudes towards the conservation of wildlife species. Using semi-structured interviewing and free listing (n = 191) as part of a mixed methods approach, we first characterized local aesthetic judgments of wildlife species. With a Generalized Linear Mixed Models (GLMM) approach, we then determined the influence of perceiving four species as beautiful on local support for their protection ("rescuing them"), and of perceiving four other species as ugly on support for their removal from the area, while controlling for informant personal and household socioeconomic attributes. Perceiving giraffe, gazelles and eland as beautiful is the strongest variable explaining support for rescuing them. Ugliness is the strongest variable influencing support for the removal of buffalo, hyena, and elephant (but not lion). Both our qualitative and quantitative results suggest that perceptions of ugly species could become more positive through direct exposure to those species. We propose that protected areas in developing countries facilitate visitation by local residents to increase their familiarity with species they rarely see or most frequently see in conflict with human interests. Since valuing a species for its beauty requires seeing it, protected areas in developing countries should connect the people who live around them with the animals they protect. Our results also show that aesthetic appreciation of biodiversity is not restricted to the industrialized world.

A quasi-experimental analysis of maternal altitude exposure and infant birth weight

OBJECTIVES

We analyzed singleton births to determine the relationship between birth weight and altitude exposure.

METHODS

We analyzed 715,213 singleton births across 74 counties from the western states of Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, and Washington from January 1, 2000, to December 31, 2000. Birth data were obtained from the Division of Vital Statistics, National Center for Health Statistics, for registered births.

RESULTS

Regression analyses supported previous research by showing that a 1000-meter increase in maternal altitude exposure in pregnancy was associated with a 75.9-gram reduction in birth weight (95% confidence interval = -84.1, -67.6). Quantile regression models indicated significant and near-uniform depressant effects from altitude exposure across the conditional distribution of birth weight. Bivariate sample-selection models showed that a 1000-meter increase in altitude exposure, over and above baseline residential altitude, decreased birth weight by an additional 58.8 grams (95% confidence interval = -98.4, -19.2).

CONCLUSIONS

Because of calculable health care-related costs associated with lower birth weight, our reported results might be of interest to clinicians practicing at higher altitudes.

A formal anthropological view of motivation models of problematic MMO play: achievement, social, and immersion factors in the context of culture

Yee (2006) found three motivational factors-achievement, social, and immersion-underlying play in massively multiplayer online role-playing games ("MMORPGs" or "MMOs" for short). Subsequent work has suggested that these factors foster problematic or addictive forms of play in online worlds. In the current study, we used an online survey of respondents (N = 252), constructed and also interpreted in reference to ethnography and interviews, to examine problematic play in the World of Warcraft (WoW; Blizzard Entertainment, 2004-2013). We relied on tools from psychological anthropology to reconceptualize each of Yee's three motivational factors in order to test for the possible role of culture in problematic MMO play: (a) For achievement, we examined how "cultural consonance" with normative understandings of success might structure problematic forms of play; (b) for social, we analyzed the possibility that developing overvalued virtual relationships that are cutoff from offline social interactions might further exacerbate problematic play; and (c) in relation to immersion, we examined how "dissociative" blurring of actual- and virtual-world identities and experiences might contribute to problematic patterns. Our results confirmed that compared to Yee's original motivational factors, these culturally sensitive measures better predict problematic forms of play, pointing to the important role of sociocultural factors in structuring online play.

Economics of disaster risk, social vulnerability, and mental health resilience

We investigate the relationship between exposure to Hurricanes Katrina and/or Rita and mental health resilience by vulnerability status, with particular focus on the mental health outcomes of single mothers versus the general public. We advance a measurable notion of mental health resilience to disaster events. We also calculate the economic costs of poor mental health days added by natural disaster exposure. Negative binomial analyses show that hurricane exposure increases the expected count of poor mental health days for all persons by 18.7% (95% confidence interval [CI], 7.44-31.14%), and by 71.88% (95% CI, 39.48-211.82%) for single females with children. Monthly time-series show that single mothers have lower event resilience, experiencing higher added mental stress. Results also show that the count of poor mental health days is sensitive to hurricane intensity, increasing by a factor of 1.06 (95% CI, 1.02-1.10) for every billion (U.S.$) dollars of damage added for all exposed persons, and by a factor of 1.08 (95% CI, 1.03-1.14) for single mothers. We estimate that single mothers, as a group, suffered over $130 million in productivity loss from added postdisaster stress and disability. Results illustrate the measurability of mental health resilience as a two-dimensional concept of resistance capacity and recovery time. Overall, we show that natural disasters regressively tax disadvantaged population strata.

Maternal hurricane exposure and fetal distress risk

Logistic regression and spatial analytic techniques are used to model fetal distress risk as a function of maternal exposure to Hurricane Andrew. First, monthly time series compare the proportion of infants born distressed in hurricane affected and unaffected areas. Second, resident births are analyzed in Miami-Dade and Broward counties, before, during, and after Hurricane Andrew. Third, resident births are analyzed in all Florida locales with 100,000 or more persons, comparing exposed and unexposed gravid females. Fourth, resident births are analyzed along Hurricane Andrew's path from southern Florida to northeast Mississippi. Results show that fetal distress risk increases significantly with maternal exposure to Hurricane Andrew in second and third trimesters, adjusting for known risk factors. Distress risk also correlates with the destructive path of Hurricane Andrew, with higher incidences of fetal distress found in areas of highest exposure intensity. Hurricane exposed African-American mothers were more likely to birth distressed infants. The policy implications of in utero costs of natural disaster exposure are discussed.

Impaired sensory processing as a basis for object-recognition deficits in schizophrenia

OBJECTIVE

Individuals are able to recognize common objects even when portions of them are obscured from view, reflecting the operation of neural perceptual closure processes. This study evaluates the integrity of object recognition and perceptual closure as a function of sensory and cognitive manipulations.

METHOD

Object recognition was examined in 26 subjects with schizophrenia and 23 nonpsychiatric comparison subjects of similar age with a presentation of fragmented pictures by means of the ascending method of limits. The effects of prior exposure to subsets of stimuli and of word prompting were examined in separate testing phases. Demographic and clinical characteristics were evaluated as covariates.

RESULTS

Although they had impairments in perceptual closure, schizophrenic patients showed improvement in performance equivalent to that of nonpatient comparison subjects with prior exposure to the pictures (i.e., repetition priming) and with presentation of valid word prompts. A significant correlation was found between impaired performance and the severity of negative symptoms.

CONCLUSIONS

The results support models of widespread dysfunction in information processing in patients with schizophrenia involving both sensory and cognitive regions. Perceptual closure is significantly impaired in schizophrenic patients; however, this deficit in sensory precision is dissociated from the effects of higher-order repetition priming and word prompting. Furthermore, this work suggests that deficits in perceptual closure may contribute to the muted world experience of patients with the persistent negative symptoms of schizophrenia.

Recognition and source memory for pictures in children and adults

The present experiment investigated the developmental aspects of source compared to item memory. College students and 7-8-year-old children viewed pictures drawn in red or green during a study phase, and were asked either to remember the pictures for a subsequent recognition test, or to remember both the pictures and their associated colors for a subsequent source memory test. In the test phase, new and old pictures were presented in black. In the recognition task, participants were asked to make binary old/new recognition judgments, while in the source task, they were asked to make trinary old-green/old-red/new source judgements. Performance on all tasks improved with increasing age, but the age difference for source was much larger than that for item memory. It has been suggested that the frontal lobes play a critical role in the retrieval of source information, and that this brain region relative to the medial temporal lobes continues to develop into late adolescence. Thus, it is possible that immaturity of the frontal lobes may be causally related to the children's lower performance on the source memory task.

Remembering the color of objects: an ERP investigation of source memory

Subjects studied pictures of common objects outlined in either red or green and were asked to memorize the objects and their associated colors. Event-related potentials (ERPs) were recorded during subsequent inclusion (i.e. item) and exclusion (i.e. source) memory tasks. The main goal of the experiment was to determine if brain signatures for familiarity and recollection, two behavioral processes thought to account for episodic memory performance, would be observed in the pattern of ERP results. For correctly recognized items, early, posterior old/new effects were recorded (approximately 300--600 ms) that did not differ in magnitude or scalp distribution between item and source memory tasks. A subsequent long-duration occipitally focused negativity (approximately 800 ms peak) was evident in the source but not the item memory task. The ERPs associated with 'source errors' in the source memory task also showed robust early old/new effects. However, 'source error' ERPs lacked frontal scalp activity compared to those associated with correct source attribution. The data suggest that a recollective response may require frontal involvement whereas a decision based on familiarity may not.

Activation timecourse of ventral visual stream object-recognition areas: high density electrical mapping of perceptual closure processes

Object recognition is achieved even in circumstances when only partial information is available to the observer. Perceptual closure processes are essential in enabling such recognitions to occur. We presented successively less fragmented images while recording high-density event-related potentials (ERPs), which permitted us to monitor brain activity during the perceptual closure processes leading up to object recognition. We reveal a bilateral ERP component (N(cl)) that tracks these processes (onsets approximately 230 msec, maximal at approximately 290 msec). Scalp-current density mapping of the N(cl) revealed bilateral occipito-temporal scalp foci, which are consistent with generators in the human ventral visual stream, and specifically the lateral-occipital or LO complex as defined by hemodynamic studies of object recognition.

Does the generation effect occur for pictures?

The generation effect is the finding that self-generated stimuli are recalled and recognized better than read stimuli. The effect has been demonstrated primarily with words. This article examines the effect for pictures in two experiments: Subjects named complete pictures (name condition) and fragmented pictures (generation condition). In Experiment 1, memory was tested in 3 explicit tasks: free recall, yes/no recognition, and a source-monitoring task on whether each picture was complete or fragmented (the complete/incomplete task). The generation effect was found for all 3 tasks. However, in the recognition and source-monitoring tasks, the generation effect was observed only in the generation condition. We hypothesized that absence of the effect in the name condition was due to the sensory or process match effect between study and test pictures and the superior identification of pictures in the name condition. Therefore, stimuli were changed from pictures to their names in Experiment 2. Memory was tested in the recognition task, complete/incomplete task, and second source-monitoring task (success/failure) on whether each picture had been identified successfully. The generation effect was observed for all 3 tasks. These results suggest that memory of structural and semantic characteristics and of success in identification of generated pictures may contribute to the generation effect.

The picture superiority effect: support for the distinctiveness model

The form change paradigm was used to explore the basis for the picture superiority effect. Recognition memory for studied pictures and words was tested in their study form or the alternate form. Form change cost was defined as the difference between recognition performance for same and different form items. Based on the results of Experiment 1 and previous studies, it was difficult to determine the relative cost for studied pictures and words due to a reversal of the mirror effect. We hypothesized that the reversed mirror effect results from subjects' basing their recognition decisions on their assumptions about the study form. Experiments 2 and 3 confirmed this hypothesis and generated a method for evaluating the relative cost for pictures and words despite the reversed mirror effect. More cost was observed for pictures than words, supporting the distinctiveness model of the picture superiority effect.

A developmental trajectory in implicit memory is revealed by picture fragment completion

Dissociations between performance on implicit and explicit tasks have often been taken as evidence that different neural structures subserve the two types of memory. One such dissociation involves developmental differences that emerge in explicit tasks, but which appear to be absent in implicit tasks. Such findings are consistent with the idea that implicit memory is subserved by a more primitive system that evolves earlier at both phylogenetic and ontogenetic levels. The present paper reviews previous studies that claimed to find evidence that implicit memory is fully developed in very young children. Issues of measurement error, ceiling effects, and insufficient power brought up questions about those studies with respect to the developmental issue. The present study compares performance on implicit (picture fragment completion) and explicit (free recall and recognition) memory tasks with groups ranging in age from 5-28 years. We find a reliable developmental trend in both implicit and explicit performance in which the former cannot be attributed to the operation of explicit memory processes. Thus, we conclude that implicit memory, like explicit memory, develops with age.

Episodic priming and memory for temporal source: event-related potentials reveal age-related differences in prefrontal functioning

Event-related potentials (ERPs) were recorded from young (M = 25) and older (M = 71) adults during a recognition memory paradigm that assessed episodic priming. Participants studied two temporally distinct lists of sentences (each with two unassociated nouns). At test, in response to the nouns, participants made old-new, followed by remember (context)-know (familiarity) and source (i.e., list) judgments. Both young and older adults showed equivalent episodic priming effects. However, compared to the young adults, the older adults showed a greater source performance decrement than item memory performance decrement. Both age groups showed equivalent posterior-maximal old-new ERP effects. However, only the young produced a frontal-maximal, late onset old-new effect that differed as a function of subsequent list attribution. Because source memory is thought to be mediated by prefrontal cortex, we conclude that age-related memory differences may be due to a deficit in a prefrontal cortical system that underlies source memory and are not likely to be due to an age-related decline in episodic priming.

Episodic priming and memory for temporal source: event-related potentials reveal age-related differences in prefrontal functioning

Event-related potentials (ERPs) were recorded from young (M = 25) and older (M = 71) adults during a recognition memory paradigm that assessed episodic priming. Participants studied two temporally distinct lists of sentences (each with two unassociated nouns). At test, in response to the nouns, participants made old-new, followed by remember (context)-know (familiarity) and source (i.e., list) judgments. Both young and older adults showed equivalent episodic priming effects. However, compared to the young adults, the older adults showed a greater source performance decrement than item memory performance decrement. Both age groups showed equivalent posterior-maximal old-new ERP effects. However, only the young produced a frontal-maximal, late onset old-new effect that differed as a function of subsequent list attribution. Because source memory is thought to be mediated by prefrontal cortex, we conclude that age-related memory differences may be due to a deficit in a prefrontal cortical system that underlies source memory and are not likely to be due to an age-related decline in episodic priming.

On the generality of the perceptual closure effect

Perceptual closure is a process whereby an incomplete stimulus is perceived to be complete. J. G. Snodgrass and K. Feenan (1990) argued that perceptual closure during a study episode is an important factor in producing large priming effects in picture fragment identification. They found that a moderately fragmented study picture produced more priming than either a very fragmented or an intact study picture and argued that this inverted U-shaped function is a signature of the perceptual closure effect. The experiments in this study, extend these results to word fragment identification by showing that (a) the most effective prime, for both unspeeded and speeded word fragment identification is a moderately fragmented study word; (b) the sharpness of the U-shaped gradient is the same whether the perceptual feedback during study is a word (in a font different from that of the fragmented study word) or a picture; and (c) although a fragmented study picture primes subsequent word fragment identification, it does not produce the inverted U-shaped function, thereby showing that perceptual closure reflects perceptual rather than conceptual priming.

On the generality of the perceptual closure effect

Perceptual closure is a process whereby an incomplete stimulus is perceived to be complete. J. G. Snodgrass and K. Feenan (1990) argued that perceptual closure during a study episode is an important factor in producing large priming effects in picture fragment identification. They found that a moderately fragmented study picture produced more priming than either a very fragmented or an intact study picture and argued that this inverted U-shaped function is a signature of the perceptual closure effect. The experiments in this study, extend these results to word fragment identification by showing that (a) the most effective prime, for both unspeeded and speeded word fragment identification is a moderately fragmented study word; (b) the sharpness of the U-shaped gradient is the same whether the perceptual feedback during study is a word (in a font different from that of the fragmented study word) or a picture; and (c) although a fragmented study picture primes subsequent word fragment identification, it does not produce the inverted U-shaped function, thereby showing that perceptual closure reflects perceptual rather than conceptual priming.

Picture naming by young children: norms for name agreement, familiarity, and visual complexity

Researchers concerned with the development of cognitive functions are in need of standardized material that can be used with both adults and children. The present article provides normative measures for 400 line drawings viewed by 5- and 6-year-old children. The three variables obtained-name agreement, familiarity, and visual complexity-are important because of their potential effect on memory and other cognitive processes. The normative data collected in the present study indicate that young children are different from adults in both the name most frequently assigned and the number of alternative names provided. The alternative names given by the children are either coordinate names or names of objects that are visually similar to the pictured object. In addition, the failure (to name) rate is higher among young children compared to adults. Thus, we conclude that unequivocal interpretation of age-related differences in cognitive functions can be made only when age-appropriate pictorial stimuli are chosen.

ERPs during study as a function of subsequent direct and indirect memory testing in young and old adults

Event-related potentials (ERPs) were recorded from young and older adults while words were studied during structural and semantic encoding tasks. Items were presented twice to assess repetition effects. Subsequent memory effects (i.e. Dm or difference in subsequent memory) associated with non-target study items were also evaluated. Memory for non-target study items was tested either indirectly (word stem completion) or directly (cued recall). There were small, but unreliable age differences (favoring the young) on both the indirect and direct tests. These small differences were consistent with previous results for stem completion performance, but were counter to expectation for the cued recall test, where young adults were expected to show clear superiority. We conclude, based on task considerations, that for cued recall, subjects may have adopted an 'implicit' retrieval strategy. Because older adults typically have little difficulty with implicit retrieval, they fared almost as well as the young on cued recall. Dm effects were reliable for the young only. As Dm is thought to reflect elaborative encoding processes, the larger Dm magnitudes in the young than the old suggest that the small, though unreliable, age-related performance differences that resulted may have been mediated by such elaborative processing on the part of the younger adults.

Implicit retrieval processes in cued recall: implications for aging effects in memory

Aging produces deficits in what has come to be called explicit or direct memory, in which subjects must consciously retrieve information from long-term memory. In contrast, many studies have shown that when implicit or indirect memory is tested, old and young subjects perform equivalently. The present study manipulated orienting instructions (structural vs. semantic) for indirect (stem completion) and direct (cued recall) memory tasks for both young and old subjects. Contrary to previous research, older subjects produced equivalent performance to young subjects on the direct test as well as on the indirect test, and performance of both groups was worse in the direct than indirect test. In addition, semantic orienting activity at study led to greater learning on the indirect test than structural orienting for both groups, although the levels of processing effect was greater for the direct test. We attribute the unexpected lack of age difference on the direct test to its difficulty, which led subjects to adopt an implicit (generate + recognize) rather than an explicit retrieval strategy during the cued recall task. Because the elderly are not impaired with regard to either implicit retrieval or recognition, this strategy produced equivalent performance in the two groups.

Dissociations among implicit and explicit memory tasks: the role of stimulus similarity

This article compares the effect of picture fragmentation level at study on performance on a variety of implicit and explicit memory tests. Consistent with previous research, a moderately fragmented study picture produced the most learning on the implicit memory task of picture fragment completion (Experiment 1) and speeded picture identification (Experiment 4). In contrast, an intact study picture produced the most learning on the implicit memory task of naming intact pictures (Experiment 3). These results suggest that performance on 2 implicit memory tasks can be dissociated by differences in visual similarity between the study and test forms of a stimulus. More surprising, parallel effects were observed in recognition memory. Recognition memory was best when fragmentation levels of the study and test pictures matched (Experiment 2) or were comparable (Experiment 1). In contrast to many results in the literature, recognition memory was acutely sensitive to surface form differences. We discuss the results in terms of 2 types of study-test similarity-stimulus similarity and process similarity.

Dissociations among implicit and explicit memory tasks: the role of stimulus similarity

This article compares the effect of picture fragmentation level at study on performance on a variety of implicit and explicit memory tests. Consistent with previous research, a moderately fragmented study picture produced the most learning on the implicit memory task of picture fragment completion (Experiment 1) and speeded picture identification (Experiment 4). In contrast, an intact study picture produced the most learning on the implicit memory task of naming intact pictures (Experiment 3). These results suggest that performance on 2 implicit memory tasks can be dissociated by differences in visual similarity between the study and test forms of a stimulus. More surprising, parallel effects were observed in recognition memory. Recognition memory was best when fragmentation levels of the study and test pictures matched (Experiment 2) or were comparable (Experiment 1). In contrast to many results in the literature, recognition memory was acutely sensitive to surface form differences. We discuss the results in terms of 2 types of study-test similarity-stimulus similarity and process similarity.

Neighborhood effects in visual word recognition: facilitatory or inhibitory?

In five experiments, in which subjects were to identify a target word as it was gradually clarified, we manipulated the target's frequency of occurrence in the language and its neighborhood size--the number of words that can be constructed from a target word by changing one letter, while preserving letter position. In Experiments 1-4, visual identification performance to screen-fragmented words was measured. In Experiments 1 and 2, we used the ascending method of limits, whereas Experiments 3 and 4 presented a fixed-level fragment. In Experiment 1, there was no relation between overall accuracy and neighborhood size for words between three and six letters in length. However, more errors of commission (guesses) were made for high-neighborhood words and more errors of omission (blanks) were made for low-neighborhood words. Letter errors within guesses occurred at serial positions having many neighbors, and these positions were also likely to contain consonants rather than vowels. In Experiment 2, a small facilitatory effect of neighborhood size on both high- and low-frequency words was found. In contrast, in Experiments 3 and 4, using the same set of words, inhibitory effects of neighborhood size, but only for low-frequency words, were found. Experiment 5, using a speeded identification task, showed results parallel to those of Experiments 3 and 4. We suggest that whether neighborhood effects are facilitatory or inhibitory depends on whether feedback allows subjects to disconfirm initial hypotheses that the target is a high-frequency neighbor.

Priming effects in picture fragment completion: support for the perceptual closure hypothesis

The perceptual closure hypothesis says that priming will be optimum when just enough information is available in the prime to support closure. Across 5 experiments, a moderately complete fragmented image (Level 4) produced more priming than an almost complete (Level 7) or a very incomplete (Level 1) fragmented image. Only Level 4 priming was improved by increases in prime duration and by showing the prime again after Ss attempted to identify it. Explicit memory played little role in primed fragment completion except for Level 1 priming, in which specific fragment memory was responsible for the entire effect. In contrast, true perceptual learning was shown to be responsible for Level 4 and Level 7 priming. These priming effects cannot be accounted for by the transfer-appropriate procedures approach of Roediger and his colleagues because Level 1 priming produced less transfer to Level 1 identification at test than Level 4 priming did.

The effect of context on discrimination and bias in recognition memory for pictures and words

When the context accompanying a to-be-remembered word is changed between study and test, recognition memory is impaired. The deleterious effect of context change on recognition memory can be viewed as support for encoding specificity theory, semantic theory, or the existence of two bases for recognition. A fourth possible interpretation, examined here, is that the effect of context change on recognition memory is due to an accompanying change in response bias, rather than a "true" decrease in sensitivity to old and new items. In two experiments, the effect of context change on discrimination and bias in recognition of simple line drawings and their names was examined. Bias was measured using two measures shown by Snodgrass and Corwin (1988) to be theoretically independent of their associated discrimination measures. Context change produced marked conservatism in response bias in both experiments but demonstrated an effect on discrimination in the second experiment only. The shift from a neutral to a conservative response strategy as a result of context change may also be seen in other experiments, in which the same experimental paradigm was used with a variety of stimulus materials. We suggest that the major effect of context manipulation is to produce a change in bias. A stimulus in a familiar environment appears to be more familiar than a stimulus in a strange environment, regardless of its old/new status. In addition, there appears to be a true decrease in discrimination with context change, but this is more difficult to detect. The finding that pictures, which are less polysemous than words, are as affected by context change as words are supports encoding specificity theory over semantic theory.

Priming effects in picture fragment completion: Support for the perceptual closure hypothesis

The perceptual closure hypothesis says that priming will be optimum when just enough information is available in the prime to support closure. Across 5 experiments, a moderately complete fragmented image (Level 4) produced more priming than an almost complete (Level 7) or a very incomplete (Level 1) fragmented image. Only Level 4 priming was improved by increases in prime duration and by showing the prime again after Ss attempted to identify it. Explicit memory played little role in primed fragment completion except for Level 1 priming, in which specific fragment memory was responsible for the entire effect. In contrast, true perceptual learning was shown to be responsible for Level 4 and Level 7 priming. These priming effects cannot be accounted for by the transfer-appropriate procedures approach of Roediger and his colleagues because Level 1 priming produced less transfer to Level 1 identification at test than Level 4 priming did.

Perceptual identification thresholds for 150 fragmented pictures from the Snodgrass and Vanderwart picture set

This paper reports perceptual identification thresholds for 150 pictures from the 1980 Snodgrass and Vanderwart picture set. These pictures were fragmented and presented on the Apple Macintosh microcomputer in a picture-fragment completion task in which identification thresholds were obtained at three phases of learning: Train (initial presentation), New (initial presentation after training on a different set), and Old (repeated presentation of the Train set). Pictures were divided into five sets of two subsets of 15 pictures each, which served alternately as the Train and New sets. A total of 100 subjects participated in the task, with 10 subjects assigned to each subset. Individual thresholds for each picture at each phase of learning are presented, along with the fragmented pictures identified by 35% of the subjects across the Train and New learning phases. This set of fragmented pictures is provided for use in experiments in which a single level of fragmented image is presented for identification after a priming phase. Correlations between the Snodgrass and Vanderwart norms and identification thresholds at the three phases of learning are also reported.

Pragmatics of measuring recognition memory: applications to dementia and amnesia

This article has two purposes. The first is to describe four theoretical models of yes-no recognition memory and present their associated measures of discrimination and response bias. These models are then applied to a set of data from normal subjects to determine which pairs of discrimination and bias indices show independence between discrimination and bias. The following models demonstrated independence: a two-high-threshold model, a signal detection model with normal distributions using d' and C (rather than beta), and a signal detection model with logistic distributions and a bias measure analogous to C. C is defined as the distance of criterion from the intersection of the two underlying distributions. The second purpose is to use the indices from the acceptable models to characterize recognition memory deficits in dementia and amnesia. Young normal subjects, Alzheimer's disease patients, and parkinsonian dementia patients were tested with picture recognition tasks with repeated study-test trials. Huntington's disease patients, mixed etiology amnesics, and age-matched normals were tested by Butters, Wolfe, Martone, Granholm, and Cermak (1985) using the same paradigm with word stimuli. Demented and amnesic patients produced distinctly different patterns of abnormal memory performance. Both groups of demented patients showed poor discrimination and abnormally liberal response bias for words (Huntington's disease) and pictures (Alzheimer's disease and parkinsonian dementia), whereas the amnesic patients showed the worst discrimination but normal response bias for words. Although both signal detection theory and two-high-threshold discrimination parameters showed identical results, the bias measure from the two-high-threshold model was more sensitive to change than the bias measure (C) from signal detection theory. Three major points are emphasized. First, any index of recognition memory performance assumes an underlying model. Second, even acceptable models can lead to different conclusions about patterns of learning and forgetting. Third, efforts to characterize and ameliorate abnormal memory should address both discrimination and bias deficits.

The role of visual similarity in picture categorization

Categorization is usually assumed to require access to a concept's meaning. When pictures are categorized faster than words, they are assumed to be understood faster than words. However, pictures from the same category are more similar than pictures from different categories. The present article argues that the use of visual similarity as a cue to category membership may produce the picture advantage. The visual similarity hypothesis was tested in two experiments. In the first experiment, pictures showed a disadvantage for the visually similar categories of fruits and vegetables, but showed their usual advantage for the visually dissimilar categories of fruits and animals. In the second experiment, with a mixed list design, pictures were slower only for visually similar different decisions, but showed the usual advantage for all other decisions. The reliability of visual similarity as a cue to the decision accounted well for these results. Because visual similarity can be shown to have large effects on picture categorization, the use of categorization to compare speed of understanding of pictures and words is questionable.

The role of visual similarity in picture categorization

Categorization is usually assumed to require access to a concept's meaning. When pictures are categorized faster than words, they are assumed to be understood faster than words. However, pictures from the same category are more similar than pictures from different categories. The present article argues that the use of visual similarity as a cue to category membership may produce the picture advantage. The visual similarity hypothesis was tested in two experiments. In the first experiment, pictures showed a disadvantage for the visually similar categories of fruits and vegetables, but showed their usual advantage for the visually dissimilar categories of fruits and animals. In the second experiment, with a mixed list design, pictures were slower only for visually similar different decisions, but showed the usual advantage for all other decisions. The reliability of visual similarity as a cue to the decision accounted well for these results. Because visual similarity can be shown to have large effects on picture categorization, the use of categorization to compare speed of understanding of pictures and words is questionable.