The present study tested the hypotheses that viewing loved familiar face pictures during times of aversive apprehension would reduce the impact of contextual threat signals and/or facilitate the reduction of threat effects across repeated test days. No support for these hypotheses was observed for any of the dependent variables. Similar to previous work, pronounced activation of the autonomic and somatic response systems emerged within a context of threat-of-shock relative to safety (i.e., enhanced skin conductance responses and potentiated startle reflex; Bublatzky et al., 2013, 2014a; Grillon et al., 1991; Grillon & Charney, 2011). These threat effects declined across test days but remained significant through the end of test day 3 for the startle reflex as well as threat and arousal ratings. Moreover, the impact of contextual threat was not modulated by the face category (i.e., loved vs. unknown) that was presented concurrently in the foreground. Specifically, viewing loved ones did neither modulate the threat-potentiated defensive startle reflex, enhanced skin conductance responses, nor it had an impact on the affective ratings of the threat and safety context conditions. Compared to unknown people, pictures of loved ones were perceived as more pleasant, less threatening and arousing, but these positive aspects did not affect the functioning of defensive physiological response systems during threat.
The knowledge that a particular person or situation is potentially dangerous triggers caution, aversive anticipation, and prepares avoidance or defense behavior (Bradley et al., 2005; Bublatzky et al., 2017, 2018, 2020; Grillon et al., 1991; Morato et al., 2021). Threat-related psychophysiological responding here involves preparatory activation of the somatic and autonomic nervous systems, and is adaptive in that potential harm to the organism can be avoided or reduced. However, if the expected aversive event does not occur (e.g., persistent absence of expected shocks), this does not necessarily mean that the situation is completely safe. Accordingly, defense systems remain prepared, and this is exactly what we observed. Despite the lack of shock occurrence across three test days, threat-potentiated startle reflex and more aversive self-report were found for threat relative to safety contexts until the end of the experiment. This finding replicates previous studies that show persistent effects of instructional threat learning (Bublatzky et al., 2013, 2014a) and contrast with rather quick extinction learning in studies that use shock reinforcement to acquire threat associations (e.g., Pavlovian conditioning). Thus, extinction of the pure cognitive representation of instructed threats (i.e., 0% shock reinforcement) seems to require more than the mere experience of safety (i.e., the continued absence of shocks).
Here, we examined whether viewing images of loved ones may reduce the impact of co-occurring threat signals. In contrast, our results show that pictures of loved ones neither modulated contextual threat effects (i.e., threat-potentiated startle reflex regardless of face category) nor did the physiological responding differ between pictures of loved or unknown faces. These results, based on classical null hypothesis significance tests, are supported by Bayesian analyses showing that for startle reflex and skin conductance, the null hypotheses (i.e., no interaction between face category and context) are 19.61 and 20.41 times more likely than the alternative interaction hypotheses. Moreover, this non-interactive pattern between face category and threat/safety learning goes in line with several recent studies. For instance, using personalized stimulus materials as explicitly instructed threat cues did not show an inhibition of somatic and autonomic responding towards loved faces (i.e., pictures of the spouse; Morato et al., 2021), and this was further replicated with pictures displaying smiling or angry-looking loved ones (Guerra et al., in prep.).
While some studies suggested a resistance of supportive others against becoming threatening (i.e., showing no differential conditioning; Hornstein et al., 2016, 2017), the overall pattern here does not support the notion that attachment figures are per se prepared safety cues. Indeed, this would be in line with the notion that the human face (compared to pictures of snakes or spiders; e.g., Lipp & Edwards, 2002; Öhman & Mineka, 2001) appears to be a less reliable source of implicit or inherited threat or safety information. For example, social acquisition of threat and safety associations appears to function equally well when linked to facial expressions (e.g., happy or angry faces as cues to threat; Bublatzky et al., 2018, 2019) and facial identity information, even for beloved familiar faces (Bublatzky et al., 2020; Morato et al., 2021). Thus, psychophysiological responding reflects a flexible defense activation to the threatening contextual situation (i.e., colored background), disregarding and potentially overshadowing foreground pictures of loved ones or unknown persons that are non-diagnostic with respect to shock threat.
Nonetheless, our findings seem surprising given the many positive effects of caregivers, attachment figures, and significant others on physical health, well-being, and affect regulation (Eisenberger & Cole, 2012; Uchino, 2009). For instance, holding hands with your spouse reduces reported unpleasantness of shock anticipation compared to no hand-holding or holding hands with a stranger (Coan et al., 2006, 2017). Similarly, the mere pictorial presence of loved ones (e.g., pictures of the spouse) has been hypothesized to activate a mental representation of that person, resulting in reduced pain (Eisenberger et al., 2011; Master et al., 2009), and inhibition of defensive reflex activity (Guerra et al., 2012b). With regard to the impact of significant others on learning mechanisms, the evidence is mixed and this may rely on the basic function of learning. Specifically, learning enables an individual to constantly re-align to changes in the external (social) world. Here, a ‘better safe than sorry’ strategy seems to be evolutionary more advantageous (i.e., to avoid future harm) than prioritizing attachment figures as safe by default.
Another question that arises is why viewing loved ones did not inhibit defensive responding during contextual threat (cf. Guerra et al., 2012b). While pictures of loved faces were rated as less unpleasant, arousing and threatening compared to unknown faces, this overall difference did neither modulate ratings or psychophysiological responding toward contextual threat signals, nor did it vary across test days. Autonomic and somatic responding triggered by real-world threats (i.e., acoustic startle probes and shock threat) might have been less susceptible to the mental representations of loved ones. Alternatively, the mere pictorial presence of loved ones may not have been perceived as helpful and/or supportive compared to the real presence of a supportive person. To test these hypotheses, future research may directly compare in-person, in-video, or in-picture presence of other people. Here, the physical presence or absence (e.g., in case of loss and mourning for an important person) as well as the type of pro-social or helping behavior (active vs. passive support) might be more relevant factors than the person offering support.
One of the strengths of the present study relates to the use of personalized stimulus materials, which has the advantage of engaging the participants' own social system in a laboratory setting. However, this approach also has its limitations and constraints of generality. For instance, our selection of ‘loved ones’ always included photos of parents, romantic partner, and a best friend, provided that high relationship quality was reported (Guerra et al., 2011, 2012; Vico et al., 2010). While high relationship quality does not necessarily imply perceived high social support (an often used selection criteria; e.g., Eisenberger et al., 2011), we could control for differences in familiarity, gender, and age of the used face pictures (e.g., Guerra et al., 2012; Wiese et al., 2011). Moreover, we used close-up, cutout, and grey-scaled faces displaying neutral expressions. This was done in order to reduce the impact of different situational and contextual information of the face pictures, but also led to a less naturalistic experimental situation (Schindler et al., 2019), that might have reduced inhibitory effects of the loved face category. Finally, and with regard to the used verbal learning paradigm, threat and safety contingencies were explicitly instructed and kept constant within participants and across experimental blocks and sessions. However, verbal and written statements were repeated throughout the experiment and thus reinforced shock expectancy while no shocks were actually administered. This constant violation of expectations may play a crucial role in reinforcing attentional, perceptual, and response biases toward threat (e.g., Zenses et al., 2021). Here, future research may directly focus on online expectancy ratings as a function of instructional threat and safety learning (e.g., Boddez et al., 2013; Mertens & De Houwer, 2016). Moreover, addressing the differential role of active safety learning (e.g., Christianson et al., 2012; Jovanovic et al., 2012), and distinguishing the role of imminent threat omission and safety learning may be particularly interesting for a better understanding of social learning and its relevance for successful treatment of anxious psychopathology (e.g., Askew et al., 2016; Craske et al., 2008; Willems & Vervliet, 2021).
In summary, across three repeated test days, instructed threat effects persisted despite the complete absence of aversive shocks. Moreover, no influence was observed for the co-occurring safety cues (i.e., pictures of beloved faces), providing little evidence for implicit downregulation of defensive responses when viewing pictures of beloved familiar people. These data indicate the high persistence of socially acquired threat information over time, especially in the absence of additional safety signals.