Human defensive behaviors to threat scenarios show parallels to fear- and anxiety-related defense patterns of non-human mammals

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Abstract

Defense patterns of rats and mice have been characterized in terms of the relationships between the type of defensive behavior (e.g. flight, freezing, hiding, defensive threat/attack, and risk assessment) and particular features of the eliciting (threat) stimulus and the situation in which it is encountered. Because the defense systems of rodents serve as major models for investigating and understanding both the physiology and the behavioral expression of emotional response to aversive stimuli, it is essential to evaluate whether these systems show strong parallels in human responsivity to threat.

One hundred and sixty male and female undergraduate students read a set of 12 scenarios involving a present or potential threatening conspecific, and chose a primary defensive response to each. These scenarios were designed to vary features known to influence defensive responding in rodents: magnitude of threat; escapability of the situation; ambiguity of the threat stimulus; distance between the threat and the subject; presence of a hiding place. Male and female responses to the various scenarios were highly correlated, except for yell, scream, or call for help which was frequent for females, rare for males. However, a combination of this response category with ‘attack’ showed a highly positive (+0.96) male–female correlation, across scenarios.

Correlations between manipulated (and rated) features of the threat stimulus and situation, and type of defensive behavior chosen, strongly supported a view that the patterning of defensive behavior is similar for humans and non-human mammals. Significant correlations were obtained relevant to eight specific hypotheses derived from the animal literature, with some support for two additional hypotheses (non-significant correlations averaging 0.4 or more in expected direction). While three predicted correlations were not supported in these findings, only a single significant correlation was obtained that had not been predicted on the basis of the animal literature. Although the scenario approach, and this application, have specific limitations, these results provide substantial suggestion of congruence between human and non-human mammal defense systems.

Section snippets

Hypotheses from the animal literature

The virtual absence of systematic information on normal human defensive behaviors suggests that any description and analysis of these might be helpful. However, the existence of detailed descriptive and experimental data on defensive behaviors in rats and mice also provides a set of specific hypotheses against which such human data can be evaluated [2]. These data suggest that a major factor in the organization of defense in infrahuman mammals is the ambiguity of the threat stimulus. Discrete

Materials

Twelve very brief scenarios were constructed. Each of these sets up a potential threat situation involving a threatening individual, cues of potential threat from an individual, or, (for the ‘bomb’ scenario) a threatening human-constructed device. The scenarios were designed to vary along dimensions of dangerousness; escapability; distance between threat and subject; ambiguity of threat; and availability of a place of concealment or protection. In order to quantify the position of each scenario

Ratings of scenarios

  • Dangerousness. Scenarios received ratings between 2.91 and 4.77 on the 1–5 dangerousness scale. The scenario rated as least dangerous was item (6) ‘acquaintance’. The scenario rated most dangerous was item (7) ‘park’.

  • Escapability. Escapability ratings ranged from 1.4—item (3) ‘traffic signal’ to 4.5—item (2) ‘elevator’.

  • Distant. Distance ratings were from 1 (a tie between the elevator scenario and item (8) grab) and 3.3, item (12) whisper.

  • Ambiguity. Ambiguity ratings varied between 2.2 (a tie

Sex differences

Sex differences in defensiveness began with higher female ratings of dangerousness of the scenarios. An additional difference was that for seven of the 12 scenarios, the overall pattern (i.e. proportion of each response selected as first choice) was different for men and women. These seven scenarios (bush, elevator, stoplight, corner, grab, phone, or whisper) all involve a present, or highly predictable, malicious conspecific, without any apparent weapon. Follow-up conversations with subjects

Acknowledgements

The authors would like to express their sincere gratitude to Dr Reg Wood and his Psychology classes at Honolulu Community College. We particularly appreciate the enthusiasm of these students and their willingness to respond thoughtfully and carefully to a set of difficult and time-consuming tasks.

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