A startling absence of emotion effects: Active attention to the startle probe as a motor task cue appears to eliminate modulation of the startle reflex by valence and arousal

Research has shown that during emotional imagery, valence and arousal each modulate the startle reflex. Here, two imagery-startle experiments required participants to attend to the startle probe as a simple reaction time cue. In Experiment 1, four emotional conditions differing in valence and arousal were examined. Experiment 2, to accentuate potential valence effects, included two negative high arousal, a positive high arousal and a negative low arousal condition. Imagery effectively manipulated emotional valence and arousal, as indicated by heart rate and subjective ratings. Compared to baseline, imagery facilitated startle responses. However, valence and arousal failed to significantly affect startle magnitude in both experiments and startle latency in Experiment 1. Results suggest that emotional startle modulation is eclipsed when the probe is significant for task completion and/or cues a motor response. Findings suggest that an active, rather than defensive, response set may interfere with affective startle modulation, warranting further investigation.     

Fear conditioning in psychopaths: event-related potentials and peripheral measures

Aversive pavlovian delay conditioning was investigated in a sample of 11 criminal psychopaths as identified by using the Psychopathy Checklist-Revised and 11 matched healthy controls. A painful electric stimulus served as unconditioned stimulus and neutral faces as conditioned stimuli. Event-related potentials, startle response potentiation, skin conductance response, corrugator activity, and heart rate were assessed, along with valence, arousal, and contingency ratings of the CS and US. Compared to healthy controls, psychopathic subjects failed to differentiate between the CS+/CS- as shown by an absence of a conditioned response in startle potentiation and skin conductance measures. Through use of a fear-eliciting US, these data confirm previous findings of a deficient capacity to form associations between neutral and aversive events in psychopathy that appears unrelated to cognitive deficits and is consistent with hypothesized frontolimbic deficits in the disorder.     

The neuropsychology of fear learning and fear regulation.

In the current review article it is suggested that fear is a central emotional state that can be activated by external threat cues. The subcortical defensive system cannot only be activated by intrinsically aversive events but shows also strong plasticity enabling previously innocuous stimuli to get access to the fear system after they were paired with painful outcomes. On the other hand, aversive conditioning does not only result in the acquisition of a defensive disposition, the organism also learns on a pure cognitive level that one stimulus predicts the occurrence of another stimulus. It is suggested here that potentiation of the acoustic startle reflex is a rather specific measure for fear acquisition, while skin conductance discrimination indexes contingency learning. It is shown that the acquisition of fear-potentiated startle does not require cortical processing of the conditioned stimulus. Moreover, data indicate that conditioned startle potentiation is abolished in patients with unilateral lesions of the amygdala. Finally, conditioned startle potentiation can be obtained without contingency awareness, which on the other hand is necessary for skin conductance conditioning to occur. It is suggested that the learning of stimulus relations is mediated by the hippocampus and that conditioned startle potentiation is also mediated by the hippocampus in trace conditioning.     

State anxiety and affective physiology: effects of sustained exposure to affective pictures

Effects of sustained exposure to emotional stimuli on affective reactions and their recovery were examined to determine whether increasing exposure to a specific emotional content (e.g., unpleasant) cumulatively affects physiological responses; and whether motivational activation persists following sustained exposure. Participants viewed pleasant, neutral, and unpleasant IAPS pictures, presented in blocks separated by an inter-block interval. With increasing exposure to unpleasant pictures, startle magnitude showed greater potentiation, and corrugator EMG activity increased. Both affective startle and corrugator modulation persisted following exposure to unpleasant pictures. The cumulative effects of sustained exposure to unpleasant pictures were enhanced for those reporting higher state anxiety, consistent with the hypothesis that sustained aversive exposure leads to increased defensive activation. These findings suggest sustained exposure to unpleasant pictures may induce a short-term mood state, and may be a useful paradigm to study individuals who vary in symptoms of anxiety.     

Modulation of spinal reflexes: Arousal, pleasure, action

The human startle reflex is reliably modulated by the affective valence of foreground pictures, with larger reflexes elicited when viewing unpleasant relative to pleasant scenes. If this modulation is due to priming of the defensive startle reflex by an aversive foreground, a different pattern should occur for a reflex that is not inherently defensive in nature. In the current study, affective modulation was investigated using the spinal tendinous (T) reflex, which is well documented as sensitive to differences in arousal and is involved in actions that are both appetitively and defensively motivated. As such, T reflexes elicited during unpleasant pictures were not expected to be augmented relative to those elicited in the context of pleasant pictures. Results showed that T reflexes were facilitated during processing of arousing stimuli – either pleasant or unpleasant relative to low-arousal neutral materials. These effects of emotional stimuli on T-reflex amplitude are consistent with the hypothesis that motivational priming underlies affective reflex modulation.     

Emotion processing in Psychopathy Checklist — assessed psychopathy: A review of the literature

Deficient emotional experience is recognized as one of the central features of psychopathy and an impressive body of empirical findings regarding emotion processing in psychopathy has amassed over the past several decades, resulting in two broad theoretical perspectives. The general emotional deficit perspective postulates a globally reduced capacity for emotional experience and processing across the emotional spectrum. In contrast, according to the specific emotional deficit perspective, psychopathy is associated with abnormal experience of only specific types of emotion; several distinct hypotheses have been proposed under this latter perspective. We systematically and critically review findings from peer-reviewed research of emotion processing in psychopathy in relation to the two theoretical perspectives. In general, findings suggest that, compared to controls, psychopaths exhibit behavioral, psychophysiologic, and regional brain activation anomalies when processing emotion, but their ratings of self-arousal and stimulus valence/intensity do not differ from controls. However, when behavioral findings are examined separately by emotion type, the overall pattern of findings is not clearly consistent with any of the dominant theoretical perspectives of emotion processing in psychopathy. We summarize the current state of the field, including consistencies and inconsistencies in the literature, offer alternative explanations for the findings, and outline directions for future research.     

Deficient fear conditioning and self‐reported psychopathy: The role of fearless dominance

The role of the two dimensions of psychopathy—dispositional fearlessness (theorized to reflect variations in reactivity of the brain's defensive system) and externalizing proneness (presumed to reflect variations in function of anterior regulatory systems)—in fear learning was examined in a sample of undergraduates assessed using the Psychopathic Personality Inventory‐Revised (PPI‐R) who participated in a differential aversive conditioning task. Only scores on self‐reported “fearless dominance,” irrespective of scores on “impulsive antisociality,” were related to diminished acquisition of physiological fear. Consistent with dual‐process accounts of psychopathy proposing divergent etiological pathways for the interpersonal/affective and the social deviance features of the disorder, our results lend support to the existence of a deficit in reactivity of the brain's defensive system underlying the fearlessness dimension of psychopathy.     

Prediction and perception: Defensive startle modulation

Previous research indicates that predictive cues can dampen subsequent defensive reactions. The present study investigated whether effects of cuing are specific to aversive stimuli, using modulation of the blink startle reflex as a measure of emotional reactivity. Participants viewed pictures depicting violence, romance/erotica, or mundane content. On half of all trials, a cue (color) predicted the content of the upcoming picture; on the remaining trials, scenes were presented without a cue. Acoustic startle probes were presented during picture viewing on trials with predictive cues and trials without a cue. Replicating previous studies, blink reflexes elicited when viewing violent pictures that had not been preceded by a cue were potentiated compared to uncued mundane scenes, and reflexes were attenuated when viewing scenes of erotica/romance that had not been cued. On the other hand, reflex potentiation when viewing scenes of violence (relative to mundane scenes) was eliminated when these pictures were preceded by a predictive cue, whereas scenes of romance prompted reliable reflex attenuation regardless of whether pictures were cued or not. Taken together, the data suggest that cuing elicits an anticipatory coping process that is specific to aversive stimuli.     

Electrodermal hyporeactivity and antisocial behavior: does anxiety mediate the relationship?

Electrodermal hyporeactivity in the anticipation of aversive stimuli is a highly reliable correlate of diagnosed psychopathy and undersocialized aggressive conduct disorder (UACD), and it has been interpreted as reflecting a weak behavioral inhibition system (BIS) as conceptualized in Gray's work (e.g., in: Royce, J.R. (Ed.), Multivariate Analysis and Psychological Theory. Academic Press, New York, NY, p. 409, 1973). This interpretation predicts that electrodermal hyporeactivity should be associated with a single dimension of temperament involving both low anxiety and behavioral disinhibition. However, temperament scales identify separate dimensions of trait anxiety/neuroticism and inhibitory control, and most investigators have assumed that the BIS is associated with the trait anxiety/neuroticism dimension. The present review supports the view that electrodermal hyporeactivity is associated with both low anxiety and disinhibition, as expected, and, possibly, with poor control of emotional expression. Additionally, electrodermal hyporeactivity appears to relate to an impulsivity dimension among psychopaths rather than to the core personality features of psychopathy. Recent findings raise the possibility that psychopaths suffer from a broader deficit (sometimes described as an executive function deficit) than a weak BIS and that electrodermal hyporeactivity might relate to this broader deficit. It is proposed that problems with impulsivity are more strongly documented than the broader concept of executive function deficits and that a primary disinhibition can produce secondary executive function deficits. A disinhibitory deficit is consistent with the weak BIS hypothesis. Overall, the results appear to be consistent with the electrodermal hyporeactivity-weak BIS hypothesis, but many issues remain to be resolved.     

Postauricular reflexes elicited by soft acoustic clicks and loud noise probes: Reliability,prepulse facilitation,and sensitivity to picture contents

The startle blink reflex is facilitated during early picture viewing, then inhibited by attention during pleasant and aversive pictures compared to neutral pictures, and finally potentiated during aversive pictures specifically. However, it is unclear whether the postauricular reflex, which is elicited by the same loud acoustic probe as the startle blink reflex but enhanced by appetitive instead of defensive emotion, has the same pattern and time course of emotional modulation. We examined this issue in a sample of 90 undergraduates using serially presented soft acoustic clicks that elicited postauricular (but not startle blink) reflexes in addition to standard startle probes. Postauricular reflexes elicited by both clicks and probes correlated during food and nurturant contents, during which they were potentiated compared to neutral pictures, suggesting clicks effectively elicit emotionally modulated postauricular reflexes. The postauricular reflex was initially facilitated during the first 500 ms of picture processing but was larger during pleasant than neutral pictures throughout picture processing, with larger effect sizes during the latter half of picture processing. Across reflexes and eliciting stimuli, measures of emotional modulation had higher coefficient alphas than magnitudes during specific picture contents within each valence, indicating that only emotional modulation measures assess higher‐order appetitive or defensive processing.     

Aversive Pavlovian conditioning in psychopaths: peripheral and central correlates

Differential aversive Pavlovian conditioning with a foul odor as unconditioned stimulus (US) and neutral faces as conditioned stimuli (CS) was compared between 9 noncriminal psychopaths as defined by the Hare Psychopathy Checklist Revised and 12 healthy controls. Event-related potentials (ERP), heart rate, skin conductance response, corrugator EMG, and startle response potentiation as well as valence, arousal, and contingency of the CS were assessed. Whereas the healthy controls (HC) showed significant CS +/CS- differentiation, the psychopaths (PP) failed to exhibit a conditioned response although unconditioned responses were comparable between the groups. N100, P200, and P300 to the CSs revealed that psychopaths were not deficient in information processing and showed even better anticipatory responding than the HC group indicated by the terminal contingent negative variation (tCNV), that lacked, however, CS+ and CS- differentiation. These data indicate a deficit in association formation in psychopaths that may be related to deficient interaction of limbic-subcortical and cortical structures.     

Escaping aversive exposure

This research examined human defensive reactivity when exposure to an aversive event could be escaped but not entirely avoided. Prolonged visual cues indicated whether exposure to an upcoming aversive (i.e., disgusting) picture could be terminated after onset (escaped) or not, or that a neutral go signal would appear. Acoustically elicited startle reflexes were measured during each cue interval, as were cardiac and skin conductance activity. Early in the cuing interval, startle reflexes were potentiated during both escape and inescapable exposure trials, compared to the simple motor context. Later in the interval, reflexes remained potentiated for both escapable and inescapable trials, with potentiation further enhanced when aversive exposure could not be escaped compared to when exposure could be escaped. Heart rate deceleration in the cuing interval indicated increased vigilance when preparing any (escape or neutral) action, whereas skin conductance responding indicated enhanced sympathetic action mobilization particularly in an escape context. These data suggest that startle reflexes engaged in an escape context reflect both motor‐related response inhibition and aversive potentiation, and they indicate that defensive motivation is engaged whenever aversive exposure is guaranteed, regardless of whether it can be escaped or not.     

Abnormal Processing of Affective Words by Psychopaths

We tested the hypothesis that psychopathy is associated with abnormal processing of affective verbal material. Criminal psychopaths and nonpsychopaths, defined by the Psychopathy Checklist, performed a lexical decision task (“Is it a word or not”) while we recorded reaction time and eventrelated potentials in response to letter-strings consisting of affective and neutral words and pronounceable nonwords. On the assumption that they do not make efficient use of affective information, our primary prediction was that psychopaths would show less behavioral and eventrelated potential differentiation between affective and neutral words than would nonpsychopaths. The results were in accordance with this prediction. The lexical decisions of nonpsychopaths were significantly faster, and relevant event-related potential components were significantly larger, to affective words than to neutral words. In sharp contrast, psychopaths failed to show reaction lime facilitation or larger amplitude event-related potentials to affective words. We suggest that psychopaths extract less information from affective words than do other individuals. Possible implications of these and related findings for understanding the behavior of psychopaths are discussed.     

Differential motivational responses to food and pleasurable cues in anorexia and bulimia nervosa: a startle reflex paradigm

BACKGROUND: Abnormal perceptions of food and shape underpin the cognitive behavioural model of eating disorders (EDs). The aim of this study was to investigate motivational processing of disorder-specific and standard emotional cues in anorexia (AN) and bulimia nervosa (BN) using startle eyeblink modulation (SEM). SEM was used because it is sensitive to motivational states of approach (appetitive response) and withdrawal (aversive response), which are independent of conscious intentional control. METHOD: Acoustically elicited SEM and subjective anxiety ratings were measured in 30 female patients with an ED (n=15 AN, n=15 BN) and 30 female control subjects while they viewed ED-relevant stimuli (food, female bodies) and standardized emotional pictures. RESULTS: BN subjects showed an appetitive response (startle inhibition) to food relative to neutral cues that differed significantly from AN subjects. By contrast, self-reports indicated significantly increased anxiety related to food cues across both ED groups. To female body picture (relative to neutral) cues, no significant between-group differences were found for SEM. ED subjects unexpectedly showed an aversive response (startle potentiation) to positive cues, in contrast to controls, who showed the established startle attenuation. CONCLUSIONS: These preliminary results suggest that BN patients demonstrated an exaggerated appetitive response to food but not to standardized positive cues, whereas SEM in AN patients points to a generalized failure to activate the appetitive motivational system. Differences in motivational salience to food cues are in line with distinctions between AN and BN in eating behaviour and food consumption and support differential treatment requirements.     

Startle reflex modulation during threat of shock and “threat” of reward

During threat of shock, the startle reflex is potentiated, suggesting modulation by defensive mobilization. To determine whether startle potentiation is specific to aversive anticipation, startle reflexes were measured in the context of either aversive or appetitive anticipation in a between‐subject study. Participants wore a device on the wrist that could deliver electrical shock (n = 49), or vibrotactile stimulation indicating monetary reward (n = 48). Cues signaling “threat” or “safe” periods were presented alone, or accompanied by presentation of affective and neutral pictures on half of the trials. Results indicated that the startle reflex was significantly potentiated when anticipating either shock or reward, compared to safe periods, both when no picture was presented, as well as during picture viewing. The difference between threat and safety in both reflex magnitude and skin conductance changes was larger for those anticipating shock, suggesting that the aversive context was more motivationally engaging. The pattern of reflex modulation as a function of picture valence varied under threat and safety, but was identical in the shock and reward groups, consistent with a hypothesis that anticipation of either aversive or appetitive events prompts heightened perceptual vigilance, potentiating the acoustic startle reflex.     

Aversive picture processing: Effects of a concurrent task on sustained defensive system engagement

Viewing a series of aversive pictures prompts emotional reactivity reflecting sustained defensive engagement. The present study examined the effects of a concurrent visual task on autonomic, somatic, electrocortical, and facial components of this defensive state. Results indicated that emotional activation was largely preserved despite continuous visual distraction, although evidence of attenuation was observed in startle reflex and electrocortical measures. Concurrent task‐specific reactivity was also apparent, suggesting that motivational circuits can be simultaneously activated by stimuli with intrinsic survival significance and instructed task significance and that these processes interact differently across the separate components of defensive engagement.     

Association between alcohol-cue modulated startle reactions and drinking behaviour in alcohol dependent patients — results of the PREDICT study

Previous research on alcohol dependent patients has shown that variations in eyeblink startle response can be used as an indicator of their emotional responses to alcohol-related stimuli. Postulating that reactions on substance associated stimuli are controlled by either a negative or a positive affective processing system, we expect that abstinent alcoholics react differently (within-group) in the emotional evaluation of alcohol cues. Furthermore, we assumed the startle response to covary with medication response to acamprosate and naltrexone.     

Association between alcohol-cue modulated startle reactions and drinking behaviour in alcohol dependent patients — results of the PREDICT study

Previous research on alcohol dependent patients has shown that variations in eyeblink startle response can be used as an indicator of their emotional responses to alcohol-related stimuli. Postulating that reactions on substance associated stimuli are controlled by either a negative or a positive affective processing system, we expect that abstinent alcoholics react differently (within-group) in the emotional evaluation of alcohol cues. Furthermore, we assumed the startle response to covary with medication response to acamprosate and naltrexone.We measured 74 detoxified inpatients' acoustic startle responses while they were being presented with alcohol-related images as well as affectively negative, neutral, and positive pictures before they were randomized to pharmacotherapy.Group-mean startle peak amplitudes were lowest for alcohol-related cues. The relative startle response (alcohol cues set in relation to the other stimulus categories) did not correlate with craving for alcohol (OCDS) or alcohol cue induced self-ratings of arousal, valence and craving. Patients with a lower percentage of abstinent days in the 90 days prior to the last drinking day showed a lower (“more appetitive”) startle response to alcohol cues. A survival analysis using the time to first heavy drinking day as the survival criterion revealed a significant interaction between alcohol-cue startle responses and medication type.The results indicate that the psycho-physiological measure of emotional evaluation of alcohol cues includes unconscious processing not reflected by conscious self-ratings. Furthermore, our result of a differential medication effect may encourage further studies to use biological characteristics to stratify patients as a step towards individualized treatment for alcohol dependence.     

Emotional deficits in psychopathy and sexual sadism: implications for violent and sadistic behavior

While both psychopaths and sexual sadists engage in acts of predatory violence, little empirical work has examined the relationship between the two disorders. This paper outlines the constructs of psychopathy and sexual sadism and reviews the literature investigating the emotional lives of individuals with these disorders, paying particular attention to how emotional deficits might facilitate instrumental violence. Specifically, it is hypothesized that the emotion recognition and emotional experience deficits found among psychopaths, and perhaps present in sexual sadists, may lead to deficits in their ability to empathize with others, resulting in an increased likelihood for perpetrating instrumental violence. The relationship between empathy and aggression in psychopaths and sexual sadists is discussed, and distinctions are drawn between the two disorders with respect to their capacities to experience cognitive and affective empathy on a global level. Gaps in the literature are identified and additional areas of inquiry are suggested.     

Startle potentiation in aversive anticipation: evidence for state but not trait effects

The present study was undertaken to determine whether aversiveness contributes to startle potentiation in anticipation of affective pictures above and beyond the effects of emotional arousal. Further, participants high in trait anxious apprehension, which is characterized by worry about the future, were expected to show especially pronounced anticipatory startle responses. Startle blink reflex was measured during warning stimuli that predicted the valence of ensuing aversive/unpleasant, pleasant, or neutral pictures. Startle magnitude was larger in anticipation of aversive than of pleasant pictures and smallest in anticipation of neutral pictures. Enhanced startle potentiation was not found in anxious apprehension subjects. These data suggest that the aversive nature of stimuli contribute to the potentiation of startle above and beyond the effects of emotional arousal, which may be a universal phenomenon not modulated by individual differences.