Threat Signals Research Articles

Effect of task conditions on brain responses to threatening faces in social phobics: An event-related functional magnetic resonance imaging study

The aim of this study was to identify brain activation to socially threatening stimuli in social phobic subjects during different experimental conditions. With event-related functional magnetic resonance imaging, brain activation to photographs and schematic pictures depicting angry or neutral facial expressions was measured in social phobic subjects and healthy control subjects, while subjects assessed either emotional expression (angry vs. neutral; explicit task) or picture type (photographic vs. schematic; implicit task). Compared with control subjects, phobics showed greater responses to angry than to neutral photographic faces in the insula regardless of task, whereas amygdala, parahippocampal gyrus, and extrastriate visual cortex were more strongly activated only during the implicit task. Phobics, in contrast to control subjects, showed similar activation patterns during both tasks. For schematic angry versus neutral faces, activation of insula and extrastriate visual cortex was found in phobics, but not in control subjects, during both tasks. Differences between social phobics and control subjects in brain responses to socially threatening faces are most pronounced when facial expression is task-irrelevant. Phobics intensively process angry (photographic as well as schematic) facial expressions, regardless of whether this is required. The insula plays a unique role in the processing of threat signals by social phobics.

A developmental examination of gender differences in brain engagement during evaluation of threat

Background Females appear to be more sensitive and responsive to social cues, including threat signals, than are males. Recent theoretical models suggest that developmental changes in brain functioning play important roles in the emergence of such gender differences. Methods We used functional magnetic resonance imaging to examine developmental and gender differences in activation of neural structures thought to mediate attention to emotional faces depicting varying degrees of threat. Analyses focused on the orbitofrontal cortex, amygdala, and anterior cingulate cortex during the evaluation of threat conveyed by faces. Healthy adolescents ( n = 17; 53% male) and adults ( n = 17; 53% male) were scanned while they rated how threatening pictures of neutral and emotional (angry, fearful, or happy) faces appeared. Results Results indicate significant interactions among age, gender, and face type for activation during explicit threat monitoring. In particular, adult women activated orbitofrontal cortex and amygdala selectively to unambiguous threat (angry) cues, while adult men showed a less discriminating pattern of activation. No gender differences were evident for adolescents, who as a group resembled adult males. Conclusions These findings suggest that there are gender differences in patterns of neural responses to emotional faces that are not fully apparent until adulthood.

Neural Correlates of the Automatic Processing of Threat Facial Signals

The present study examined whether automaticity, defined here as independence from attentional modulation, is a fundamental principle of the neural systems specialized for processing social signals of environmental threat. Attention was focused on either scenes or faces presented in a single overlapping display. Facial expressions were neutral, fearful, or disgusted. Amygdala responses to facial expressions of fear, a signifier of potential physical attack, were not reduced with reduced attention to faces. In contrast, anterior insular responses to facial expressions of disgust, a signifier of potential physical contamination, were reduced with reduced attention. However, reduced attention enhanced the amygdala response to disgust expressions; this enhanced amygdala response to disgust correlated with the magnitude of attentional reduction in the anterior insular response to disgust. These results suggest that automaticity is not fundamental to the processing of all facial signals of threat, but is unique to amygdala processing of fear. Furthermore, amygdala processing of fear was not entirely automatic, coming at the expense of specificity of response. Amygdala processing is thus specific to fear only during attended processing, when cortical processing is undiminished, and more broadly tuned to threat during unattended processing, when cortical processing is diminished.

Signal value of alternating and overlapping singing in the Yellowhammer Emberiza citrinella

Interactive playback experiments were used to study the signal value of alternating and overlapping singing in the Yellowhammer Emberiza citrinella. We carried out interactive playback experiments in which 13 males were subjects of two treatments that differed in temporal pattern of playback song delivery (alternating vs overlapping). We measured 12 parameters of males' response, belonging to three categories: song output, call output and mobility (distance from loudspeaker and flights). The results do not confirm the hypothesis that the overlapping pattern is a signal of stronger threat, as compared to the alternating pattern. Overlapping and alternating playbacks generally elicited a similar response, characteristic for highly aroused males. The only significant difference found concerned latency of approach to the loudspeaker during the playback stage. When playback alternated with songs of males, the birds gained higher scores on the axis of that response measure. Such a result was linked to differences in how the alternating and overlapping playbacks affect detection and localisation of simulated rivals, rather than to the signal's threat value itself. The strong response of Yellowhammer males is consistent with the high intrusion rate and possibility of extra-pair copulation in this species, which probably simplifies close-range communication towards more aggressive and unequivocal repelling of rivals irrespective of the temporal patterning of song.

Characterization of human Gc protein-derived macrophage activation factor (GcMAF) and its functional role in macrophage tumoricidal activity.

Macrophages are essential for host defense and play an important role in orchestrating immune response of the host against threat signals. Macrophages are also known to have a critical role in antitumor immunity, can infiltrate into tumor, and are found in most tumor sites. Meanwhile, Gc protein (also known as vitamin D-binding protein) is a serum protein with multifunctional properties and has been reported as a precursor for macrophage activation factor. Gc protein can be converted by an inducible s-galactosidase of B cells and neuraminidase of T cells to a potent macrophage activating factor (GcMAF), a protein with N-acetylgalactosamine (GaINAc) as the remaining sugar moiety. Activated macrophages express tumoricidal activity by ingestion of tumor cells and release of reactive oxygen species (ROS) and reactive nitrogen species (RNS), or both. We reported that in situ modification of Gc protein with B-galactosidase and neuraminidase increased the release of superoxide in thioglycolate-elucidated mouse peritoneal macrophage. Yamamoto et al. reported the possibility of using GcMAF as an immunomodulator for cancer treatment, so it is important to provide an assay for GcMAF. Kanan et al. reported the quantitative analysis of GcMAF from human serum. However, the sugar moiety of GcMAF has never been qualitatively studied. Here we present the study of qualitative analysis of GcMAF from purified human serum as well as its influence on the macrophage activity.

The social risk hypothesis of depressed mood: evolutionary, psychosocial, and neurobiological perspectives.

The authors hypothesize that depressed states evolved to minimize risk in social interactions in which individuals perceive that the ratio of their social value to others, and their social burden on others, is at a critically low level. When this ratio reaches a point where social value and social burden are approaching equivalence, the individual is in danger of exclusion from social contexts that, over the course of evolution, have been critical to fitness. Many features of depressed states can be understood in relation to mechanisms that reduce social risk in such circumstances, including (a) hyper-sensitivity to signals of social threat from others, (b) sending signals to others that reduce social risks, and (c) inhibiting risk-seeking (e.g., confident, acquisitive) behaviors. These features are discussed in terms of psychosocial and neurobiological research on depressive phenomena.

Cigarette smoking and attention to signals of reward and threat in the Stroop paradigm.

To test the prediction arising from the incentive-sensitization model of addiction that when tested immediately after smoking, smokers will show heightened attention to words with appetitive and aversive motivational significance compared with their performance during acute abstinence. Twenty-one smokers were each tested twice, once just after smoking and once after overnight abstinence, on three versions of the modified Stroop task which required colour naming of words with either neutral, appetitive or aversive connotations. Ten non-smokers were tested once. All participants were tested in a quiet experimental cubicle within the psychology department. Smokers comprised nine men and 12 women who had smoked at least 10 cigarettes per day for the last 6 months; non-smokers comprised five men and five women who had never smoked. All were aged between 18 and 35 years. Three smokers were excluded from the analyses because their breath CO levels suggested they had not complied with the instructions to abstain on one occasion. A card-based, blocked, format was used for the modified Stroop task. Time to colour-name the words of the three motivational types, the order of which was counterbalanced across participants, was recorded. Smoking was associated with greater interference from both threat and appetitive words than from neutral words; during abstinence there was no differential effect of word type. Non-smokers performed more similarly to recent smokers. This pattern suggests suppression of normal motivational responding during abstinence.

Is song-type matching a conventional signal of aggressive intentions?

Song-type matching is a singing strategy found in some oscine songbirds with repertoires of song types and at least partial sharing of song types between males. Males reply to the song of a rival male by subsequently singing the same song type. For type matching to serve as an effective long-distance threat signal, it must be backed up by some probability of aggressive approach and impose some type of cost on senders that minimizes the temptation to bluff. Western subspecies of the song sparrow exhibit moderate levels of song-type sharing between adjacent males and sometimes type match in response to playback of song types they possess in their repertoires. Interactive playback experiments were used in order to examine the subsequent behaviour of type-matching birds and to quantify the responses of focal birds to type-matching versus non-matching stimuli. Birds that chose to type match the playback of a shared song type subsequently approached the speaker much more aggressively than birds that did not type match. Moreover, birds approached a type-matching stimulus much more aggressively than a non-matching stimulus. These results and consideration of alternatives suggest that type matching in song sparrows is a conventional signal in which honesty is maintained by a receiver retaliation cost against bluffers.

Postcopulatory vocalizations of fallow bucks: who is listening?

Fallow bucks (Dama dama) produce a postcopulatory vocalization (PCV), consisting of an increase in the short-term groaning rate during the first min after mating. In this article, we consider two main hypotheses to assess the possible function of the postcopulatory vocalization. First, the PCV could be directed at females, and used to advertise the current fertility status of the male. Second, the PCV could be directed at males, and used to transmit an intrasexual threat signal. We found that during days when a male gained many matings, his PCVs did not decline, and males with larger intervals between matings did not produce higher PCVs. Lower PCVs were not associated with infertile matings, and for females that mated twice within the same estrus, the PCVs of their first matings were not lower than other PCVs. In addition, higher PCVs were not associated with shorter intervals to a male’s next mating. Thus, there was no evidence to suggest that the PCV was involved in transmitting a signal of fertility assurance, either to females that had mated, or to those that were about to mate. We found that PCVs declined as males reached the end of their mating success, therefore suggesting that PCVs are more likely to be involved in transmitting an intrasexual threat signal related to current condition and/or motivation. We suggest that this signal is probably involved in mate guarding. Key words: postcopulatory vocalization, fallow deer, Dama dama, signal, fertility, body condition, motivation, mate guarding. [Behav Ecol 12:41–46 (2001)]

The timing of chemical signaling with urine in dominance fights of male lobsters ( Homarus americanus )

Chemicals carried in the urine are a rich source of information about the identity, sex, aggressive motivation, and other attributes of an animal. In agonistic interactions, animals should be careful about disclosing such information, since it can be used by receivers to the disadvantage of the sender. By adjusting the timing of urine release, the signaler may still influence the behavior of the receiver to its own benefit. Here we investigate the urine signaling of American lobsters (Homarus americanus), necessary for the maintenance of dominance, using a catheter technique with high temporal resolution. We hypothesize that urine release in lobster fights is not continuous but restricted to moments that may elicit a reaction in the receiver beneficial to the sender. We found that eventual winners signaled more readily in the initial phase of the fight. Eventual losers did not show such initial urination. This suggests that a confident lobster may use urine signals to influence the behavior of its opponent into giving up the fight at an early stage. For both winners and losers, urine release is linked to offensive behavior and increases as the intensity of agonistic behavior increases. The coupling of urine release to offensive behaviors appears to improve both the reliability and efficacy of the chemical signal. Releasing urine under the increasing risk of inflicting injury during the fight provides a handicap that may ensure reliability of the threat signal. Furthermore, the immediate coupling of urine components to offensive behavior may help to consolidate the receiver"s memory of the signaler"s individual scent and thus facilitate future recognition of the dominant animal.

Male–male competition facilitates female choice in sticklebacks

In many species, secondary sexual characteristics are used in both male–male competition and in attracting females. This suggests that social control of deception could contribute to the maintenance of honest sexual signalling. In the three–spined stickleback Gasterosteus aculeatus , male red breeding coloration plays a dual role in sexual selection by functioning as both a threat signal in male–male competition and as a cue for female choice. To investigate whether male competition determines the level of signalling, the expression of red coloration and courtship activity were recorded both before and after male interactions. The results show that male competition influences signal expression by increasing the difference between males in signalling level. This in turn facilitates female choice and induces a preference for dominant males. Since a preference for dominant males may benefit females both directly and indirectly in this species with exclusively paternal care, male–male competition seems to increase the honesty of signalling and, thus, facilitates female choice in relation to male quality. This may increase the intensity of sexual selection and promote the evolution of breeding aggregations.

Manipulations of signalling environment affect male competitive success in three-spined sticklebacks

Breeding adult male three-spined sticklebacks,Gasterosteus aculeatusL., develop an elaborate breeding signal, the primary component of which is ventral red coloration. In laboratory dominance tests staged under illumination conditions that maintained or eliminated male perceived coloration, this study examined (1) the relationship between male coloration and fighting ability and (2) the applicability of three hypotheses for the current function of male coloration in male–male competitive interactions. In pairs of males from a Long Island, NY, population matched for size and prior dominance experience, the more brightly coloured males were more likely to initiate and win under white light. The effect of colour on dominance success was lost under replicates illuminated by coloured-light treatments that masked the signal by eliminating its visual contrast. The loss of competitive advantage associated with more conspicuous coloration was not an artefact of illumination manipulations, since the effects seen under white light were maintained under a coloured-light treatment that maintained male coloration. These data suggest that red belly coloration of males functions as a threat signal.

Electronic Warfare Innovations

Abstract Modern technology has resulted in significant innovations in Electronic Warfare. The Microwave Monolithic Integrated Circuit (MMIC) program has resulted in Electronic Warfare RF receivers that are orders of magnitude smaller, lighter and cheaper than receivers produced only a few years ago. Computer processing technology is so small and fast that Electronic Warfare can digitize threat signals for identification precise enough that platforms can be identified by serial number in real‐time. Analog‐to‐Digital Converters have improved in speed and quality to permit the realization of a broadband (Gigahertz) digital receiver that preserves a quality reproduction of signals that might otherwise be lost by an analog receiver. Broadband RF components continue to progress such that subsystems and systems progress by orders of magnitude. Interferometer antenna systems that previously yielded 1.0 to 1.5 degrees direction of arrival accuracy over 2:1 RF range can be demonstrated now with 0.05 degrees accuracy over a 10: 1RF range.These and many other technologies permit the demonstration of Electronic Warfare capabilities that are finding their way into Electronic Warfare systems through engineering upgrades or entirely new systems. This paper is a synopsis of the above systems and their demonstrated performance.

Safety signals and human anxiety: a fear-potentiated startle study.

The effect of a safety signal on the magnitude of anticipatory anxiety was investigated using the fear-potentiated startle reflex paradigm in humans. The amplitude of the acoustic startle reflex was measured during the anticipation of unpleasant electric shocks ("threat") and during "safe" conditions. Threat and safe conditions were signaled by three different colored lights. Two lights signaled safe conditions (safe 1, safe 2) and the other light signaled the threat condition (threat). In phase I, the lights alternated, each presentation consisting of one colored light. In phase II, the lights were presented alone or in the two combinations of safe 1 (or safe 2) + threat and safe 1 + safe 2. In both phases, the contingency between the lights and the shock was explained to the subjects. It was emphasized that no shock could be administered when the safe 1 and threat light were simultaneously presented in phase II. Subjects' belief and understanding of the instructions were verified. In Phase I, startle was increased in the threat-alone compared to the safe-alone condition, reflecting increased anticipatory anxiety in the threat-alone condition. In phase II, startle in the safe + threat condition was smaller than in the threat-alone condition, but was larger than in the safe + threat. These results were interpreted as suggesting that the threat signal was still able to elicit anticipatory anxiety despite the fact that it was no longer associated with a threat.

Scent-marking behaviour of the ferret, Mustela furo L.

Ferrets perform a repertoire of scent-marking actions including anal drag, wiping, body rubbing and chin rubbing. Observations on ferrets in an outside enclosure revealed that anal drags were performed at latrines, often near den sites, at equal frequencies by males and females, throughout the year. Males did more wiping and body rubbing than females, especially during spring. Frequencies of chin rubbing also peaked in spring. Ferrets use a hinterland marking system, leaving marks throughout the home range. Different messages are conveyed by the various marks. Anal drags leave an olfactory signature of anal sac secretion for inter-and intrasexual communication. They would allow the assessment of the asymmetry of a conflict situation by a scent-matching mechanism or mediate a neighbour-neighbour recognition and avoidance system. Wiping and rubbing actions release the ferret's general body odour, and may act as a threat signal in agonistic encounters. The function of chin rubbing at food sites remains unclear.

Finding the face in the crowd: an anger superiority effect.

Facial gestures have been given an increasingly critical role in models of emotion. The biological significance of interindividual transmission of emotional signals is a pivotal assumption for placing the face in a central position in these models. This assumption invited a logical corollary, examined in this article: Face-processing should be highly efficient. Three experiments documented an asymmetry in the processing of emotionally discrepant faces embedded in crowds. The results suggested that threatening faces pop out of crowds, perhaps as a result of a preattentive, parallel search for signals of direct threat.

Problem-oriented participative forecasting: Theory and practice

Problem-oriented participative forecasting 1 (POPF) is an autonomous and evolving concept. It aims not only to provide early signals of threats to development or to identify opportunities for development, but also to articulate interests and mobilize different social groups to act in a manner conducive to the elimination of such threats and exploitation of such opportunities. This concept of the function of forecasting has major factual and methodological implications. The focus of this article is primarily on the forecasting process as a way of active social learning and anticipatory behaviour. It attempts to synthesize the problem-oriented and participative approaches to forecasting into a single methodology, which it documents by a specific example of its application in science forecasting in the Slovak Socialist Republic.

An experimental study of the function of the red epaulettes and the black body colour of male red-winged blackbirds

To study experimentally the function of the red epaulettes and the black body colour of adult male red-winged blackbirds, Agelaius phoeniceus, territory owners were removed and replaced with dummies. Intruding males avoided the two mounts with colourful epaulettes compared to the mount with blackened epaulettes and the mount-stand control; intruders also avoided mounts with enlarged epaulettes compared to mounts with normal-sized epaulettes. These results provide the first direct evidence that exposed epaulettes are perceived by intruders as a threat and that larger epaulettes would be more effective signals of threat than are normal epaulettes. Comparisons between the mount with blackened epaulettes and the mount-stand control showed that intruders land closer to the blackened mount than to the control. This result suggests that the conspicuous black body colour of male redwings is not threatening; it is argued that it is a distance signal of attraction that facilitates flock formation.

Communication By Agonistic Displays: Ii. Perceived Information and the Definition of Agonistic Displays

Abstract1) Great skua (Stercorarius skua) interactions were studied in the club areas of colonies on Hoy and Fair Isle. Attention was centred on reactor response to postures given by actors which did not attack or escape after displaying. 2) The regression of the reactor's escape probability on distance from the actor was analysed for Facing and Not Facing orientations of the actor. 3) Responses shown to the postures Oblique/Long Call/Wing-raising (Facing and Not Facing), Neck Straight/Bill Straight (Not Facing) and Neck Straight/Bill Straight/Long Call (Not Facing) were similar, and depended on distance, rather than the posture. This rules out the possibility that these postures constitute distinct threat signals. However, Neck Straight/Bill Straight (and Neck Straight/Bill Straight/Long Call) Facing showed a distinct pattern of response which indicated that they formed a (single) threat signal. 4) This pattern was consistent across the different colony-year samples. 5) It was concluded that the great skua behaviour patterns analysed here acted to define different situations rather than providing information about signaller intentions.

Neuronal activity of the locus ceruleus in awake Macaca arctoides

Neuronal activity in the locus ceruleus of awake, behaving stump-tailed monkeys increased consistently and vigorously after presentation of mildly aversive and threatening stimuli. These preliminary data increase the range of stimuli reported to elicit locus ceruleus activity in awake monkeys to include nonpainful threat signals and suggest that more studies are needed to be able to categorize locus ceruleus function from its unit activity responses.