Two main findings emerged in this study of parents exposed to the 9/11 terrorist attacks and their children. First, compared to parents with low levels of trauma exposure, parents with high levels of trauma exposure allocated attention towards threatening, angry faces on the dot-probe task; however, this group difference did not extend to their children. Yet, children with high exposure also tended to exhibit such a bias. Second, as threat bias in highly-exposed parents increases, threat bias in their children decreases.
The first main finding, concerning threat bias in parents with high levels of trauma exposure, can be placed in the context of previous research. Trauma-related and other forms of anxiety consistently predict biased allocation of attention to threat on the dot-probe and other attention bias tasks (Williams et al., 1996
; Bar-Haim et al., 2007
). Such associations emerge in research on diverse clinical, anxiety-related constructs, including trait anxiety, personality measures, and clinical diagnoses, such as PTSD. As with the current findings, the most consistent prior findings document a bias towards threats, such as angry faces or anxiety-related words, in anxious subjects, which significantly differs from the profile in non-anxious subjects, who typically show no bias either towards or away from threats.
Of note, few previous studies examine relationships between levels of trauma exposure and attention bias in non-clinical samples. Far more work using the dot-probe task compares anxious-traumatized subjects or subjects with PTSD to subjects with neither anxiety nor trauma (Bar-Haim et al., 2007
). As such, these studies predominantly examine people who are actively struggling with their reactions to trauma, either because trauma has occurred recently or because they have failed to overcome their initial reactions to prior trauma. The unique circumstances of the current study extend this prior work. Highly exposed parents and the small sub-sample (n=4) of highly-exposed children suffered trauma four-to-five years before the assessment of attention in the current study. As a result, unlike in prior studies, the majority were free of psychopathology. Thus, the current results suggest that the impact of long-ago experienced severe trauma may endure, as is reflected in measures of threat bias, even when clinical effects are not detected via psychiatric assessments.
Two competing explanations exist for the current unique findings on associations between trauma exposure and attention bias in parents and their children. Such competing explanations exist due to the paucity of research directly comparing correlates of attention bias in parents and their children, coupled with limitations in the current study. The most likely explanation relates to differences in severity of trauma exposure between parents and their children. The differing extremes of trauma exposure might differentially shape attention bias in parents and their children. A group of parents in the current study experienced high exposure to 9/11-related trauma. Threat bias appeared particularly large in this group. A similar pattern, though non-significant, was seen in the small subsample of highly exposed children. Thus, effects of exposure to trauma on attention bias in adults could be greater than in children, either because there are different thresholds for experience to influence bias in different age groups or because such influences are more enduring in one group. This possibility remains minimally explored. The current study is the first to compare directly attention bias among samples of potentially traumatized adults and their children, but the study contained too few children directly exposed to severe trauma to generate clear, relevant insights.
The attention bias in parents with high trauma exposure did predict bias in their children, albeit negatively. This finding is relevant to conceptualizations of parent-child transmission of trauma vulnerability. Prior work does suggest the effects of traumatic experiences on parents can, in some cases, be transmitted to their children. That is, severe trauma in parents can influence some measures of vulnerability in their children, even when these children are not directly exposed to the trauma. For example, prior studies generate such findings using measures of hypothalamic-pituitary-adrenal (HPA) axis function and severity of 9/11-related trauma (Yehuda and Bierer, 2008
). When considered in light of the current findings, this prior work suggests that exposure to trauma in parents may influence children’s measures of vulnerability in some domains, such as those related to the HPA axis or psychopathology, more strongly than others, such as those related to attention bias. However, in the current study, it is notable that threat bias correlated negatively in parents and their children among families with high exposure. This raises the possibility of intergenerational influences on attention bias, which warrant further investigation given the relatively small sample size of parents with high trauma exposure. A possible explanation is that when parents are hyper-vigilant to minor threats, reflected by behavior or attitude but not with clinical symptoms, their children may respond to the parent’s attitude with a psychological mechanism that serves to normalize this reaction.
Of note, in secondary analyses, the current study classified children based on their own, personal experiences with exposure to trauma. In these analyses, the small group of highly exposed children, like the larger group of trauma exposed parents, did exhibit bias toward threat, though the difference between children exposed to trauma and other children was not significant on statistical grounds. Thus, the increased threat bias found in trauma exposed parents but not in their children may reflect parents’ unique, personal experiences. If the current study had included more children directly experiencing exposure to severe trauma, a comparable association between trauma exposure and bias may have emerged in parents and their children. Direct exposure to trauma may be more relevant in predicting patterns of attention bias in the child than the experience of trauma in a parent.
The current findings should be interpreted in light of some clear limitations. In some instances, these limitations reflect the early stage of research in this area, where no prior studies examine associations in parents and their children among traumatic exposures, attention bias, and anxiety or other forms of psychopathology. Thus, more family-based research is needed with many other measures of cognitive vulnerability, psychopathology, distress, impairment and traumatic exposure. The current study relied on a restricted set of measures four to five years post trauma, and the findings might encourage such future attempts to use these and other measures. Measures of attentional bias scores prior to the trauma were not available; therefore, we are unable to determine how attention biases changed over time. Similarly, this initial study was based in a small sample, where parents experienced more severe trauma than their offspring. The study focused on one, relatively unique form of trauma, associated with the 9/11 terrorist attacks. Nevertheless, despite these limitations, the study was able to generate hypothesized associations in adults linking 9/11-related trauma to threat bias. Moreover, the study also was able to collect data in children’s homes on the dot-probe task, where appropriately high levels of accuracy were obtained. Thus, results from the current study should encourage attempts to examine similar associations in larger, more definitive studies.
Finally, the current study examined associations between psychopathology and threat bias four-to-five years following traumatic exposure. While highly exposed parents with low lifetime rates of psychopathology did exhibit threat bias, lifetime rates of psychopathology were determined through retrospective reports using clinical diagnostic criteria. Higher rates of psychopathology in highly exposed parents might be expected with repeated, prospective assessments, beginning immediately following severe exposure. Therefore, the absence of associations with psychopathology may reflect limitations in the assessment techniques. Moreover, recent studies suggest that relationships among trauma, attention bias, and psychopathology evolve over time following traumatic exposure (Pine et al., 2009
; Bar-Haim et al., 2010
). Thus, larger, more definitive studies might repeatedly assess both attention bias and psychopathology, in both parents and children, in the wake of severe traumatic exposure.
In closing, considerable prior work notes similarities and differences in the correlates of traumatic exposure among parents and their children. Using the dot-probe task, a standard measure of anxiety-related attention bias, the current study found that parents who had been highly exposed to 9/11-related trauma had greater attention bias to threat than low-exposed parents; moreover, the children of highly trauma-exposed parents did not share their parents’ attentional bias towards threat Additionally, as threat bias in highly-exposed parents increases, threat bias in their children decreases.