Physiological responses of obese subjects to external stimuli

Physiological arousal was measured in 11 obese and 11 normal-weight subjects during presentation of emotive, food, and neutral stimuli. No differential arousal (heart rate, temperature, GSR, and EMG on frontalis muscle) between the groups was obtained for any of the three types of stimuli. Discrepancies between the present findings and earlier results are discussed.     

Psychophysiological and subjective indices of emotion as a function of age and gender

Old, middle-aged and young persons of both genders were presented with slides containing pictorial stimuli that varied in emotional content. Each picture was rated on three dimensions: (1) valence; (2) arousal; and (3) dominance, using a 25-point scale. Heart rate, skin conductance, and forehead and cheek EMG were recorded during each slide presentation. The old and middle-aged groups showed greatly attenuated psychophysiological responses, compared to the young group. However, the old and middle-aged subjects used more extreme ratings than the young subjects on both the valence and arousal dimensions. Females were more valence-sensitive than males, but males in general used more extreme ratings of arousal than females. These results suggest a tendency to report increased felt emotion but decreased physiological response to emotional stimuli across the life span.     

The influence of affective factors on time perception

Several studies have suggested that both affective valence and arousal affect the perception of time. However, in previous experiments, the two affective dimensions have not been systematically controlled. In this study, standardized photographic slides rated for emotional valence and arousal were projected to two groups of subjects for 2, 4, and 6 sec. One group of subjects estimated the projection duration on an analog scale, whereas the second group of subjects reproduced the intervals by pushing a button. Heart rate and skin conductance responses were also recorded during stimulus presentation as indices of attention and arousal. Time estimation results showed neither a main effect of valence nor a main effect of arousal. A highly significant valence × arousal interaction affected duration judgments. For low-arousal stimuli, the duration of negative slides was judged relatively shorter than the duration of positive slides. For high-arousal stimuli, the duration of negative slides was judged longer than the duration of positive slides. The same interaction pattern was observed across judgment modalities. These results are interpreted in terms of a model of action tendency, in which the level of arousal controls two different motivational mechanisms, one emotional and the other attentional.     

Emotional distraction in boys with ADHD: Neural and behavioral correlates

Although, in everyday life, patients with attention deficit hyperactivity disorder (ADHD) are frequently distracted by goal-irrelevant affective stimuli, little is known about the neural and behavioral substrates underlying this emotional distractibility. Because some of the most important brain responses associated with the sudden onset of an emotional distracter are characterized by their early latency onset and short duration, we addressed this issue by using a temporally agile neural signal capable of detecting and distinguishing them. Specifically, scalp event-related potentials (ERPs) were recorded while 20 boys with ADHD combined type and 20 healthy comparison subjects performed a digit categorization task during the presentation of three types of irrelevant, distracting stimuli: arousing negative (A−), neutral (N) and arousing positive (A+). Behavioral data showed that emotional distracters (both A− and A+) were associated with longer reaction times than neutral ones in the ADHD group, whereas no differences were found in the control group. ERP data revealed that, compared with control subjects, boys with ADHD showed larger anterior N2 amplitudes for emotional than for neutral distracters. Furthermore, regression analyses between ERP data and subjects’ emotional ratings of distracting stimuli showed that only in the ADHD group, emotional arousal (ranging from calming to arousing) was associated with anterior N2: its amplitude increased as the arousal content of the visual distracter increased. These results suggest that boys with ADHD are more vulnerable to the distracting effects of irrelevant emotional stimuli than control subjects. The present study provides first data on the neural substrates underlying emotional distractibility in ADHD.     

Microstructure of eating behavior associated with Rorschach characteristics in obesity

The relationship between the microstructure of eating behavior and personality aspects according to the Rorschach Comprehensive System (Exner, 1991, 1993) was investigated among obese participants (N = 32). Eating behavior was measured using a computerized eating monitor, VIKTOR (Cabmek, Stockholm, Sweden), calculating initial eating rate and the eating curve. A higher initial eating rate reflecting eating drive was associated with Rorschach signs of stress overload according to the D Score and higher affective responsiveness to external stimuli seen in the Affective ratio. The stress overload may prompt eating, and affective responsiveness may be linked to appetite through a higher sensitivity to food stimuli, thus increasing eating drive. An accelerating rate of consumption during the meal was associated with intense emotionality and oral dependency, suggested by Pure C and Food responses.     

The interaction of state and trait aspects of self-focused attention affects genital, but not subjective, sexual arousal in sexually functional women

In this study we investigated the effects of state and trait aspects of self-focused attention on genital and subjective sexual arousal of sexually functional, healthy women during presentation of audiovisual erotic stimuli. Psychophysiological sexual response was measured as vaginal pulse amplitude using a vaginal photoplethysmograph. Experiential aspects of sexual arousal were measured both during stimulus presentation and retrospectively after stimulus offset. Trait level of sexual self-focus was measured with the Sexual Self-Consciousness Scale. State self-focus was induced by switching on a TV camera that pointed at the participant's face and upper torso. A manipulation check revealed that both groups experienced equally elevated levels of self-focused attention of their physical appearance. Induction of state self-focus per se did not affect genital responses, but an interaction effect of self-focus and participants' level of trait sexual self-focus was revealed. Compared with women with low scores on this trait, women with high scores exhibited smaller genital responses when state self-focus was induced. Both groups did not differ when no self-focus was induced. Increase of state self-focus did not affect subjective sexual arousal, but participants with a high level of trait sexual self-focus reported stronger subjective arousal, compared with those with low trait level. The results were discussed with reference to previous work in this field. Some implications for treatment of sexual arousal disorder were discussed.     

Psychological defense mechanisms and electroencephalographic arousal

The aim of this study was to examine the relationship between psychological defense as measured by the Kragh tachistoscopic Defense Mechanisms Test (DMT), and general arousal properties of the individual as measured with electroencephalogram (EEG). The DMT assesses defense by presenting neutral and threatening pictures with very short exposure times. EEG characteristics were measured in the 8–12 Hz EEG frequency band during DMT testing. Twenty-one male subjects participated in the study. All were US Air Force personnel on active duty. Personnel with high defense mechanisms, defined in this connection as slow perception of the threat, tended to have higher cortical arousal after Stimulus exposure than the subjects with low defense mechanisms. The differences occurred mainly with new stimulus material without any threatening content. The differences in arousal response to novel stimuli may contribute to an understanding of the relationships between the Kragh DMT test and performance in life-threatening situations.     

Cortical evoked potential, personality, and intelligence.

The averaged cortical evoked potential (CEP) was measured from 296 male subjects in two studies and was correlated with scores on intelligence and personality tests. For both studies, auditory stimuli were used with bipolar electrode placement to the Cz and T3 scalp positions. In the first study, with 84 subjects, stimulus intensity was 95 dB (all dB readings re 20 muN/m2). Intelligence was measured with the Mill Hill Vocabulary Scale and personality with H. J. Eysenck's PEN questionnaire. The second study, with 212 subjects, used additional stimuli at 75 dB and 55 dB. Intelligence was measured with the Ravens Progressive Matrices. State anxiety and other state measures at the time of testing were also taken. Neither study found any relation between the CEP and IQ or personality. However, more bored subjects showed larger CEP amplitudes. The results are discussed in terms of Ertl's neural efficiency hypothesis and Eysenck's arousal theory of personality.     

Neural correlates of subliminally presented visual sexual stimuli

In the context of forensic psychiatry, it is crucial that diagnoses of deviant sexual interests are resistant to manipulation. In a first attempt to promote the development of such tools, the current fMRI study focusses on the examination of hemodynamic responses to preferred, in contrast to non-preferred, sexual stimuli with and without explicit sexual features in 24 healthy heterosexual subjects. The subliminal stimulus presentation of sexual stimuli could be a new approach to reduce vulnerability to manipulation. Meaningful images and scrambled images were applied as masks. Recognition performance was low, but interestingly, sexual preference and explicitness modulated stimulus visibility, suggesting interactions between networks of sexual arousal and consciousness. With scrambled masks, higher activations for sexually preferred images and for explicit images were found in areas associated with sexual arousal (Stoleru, Fonteille, Cornelis, Joyal, & Moulier, 2012). We conclude that masked sexual stimuli can evoke activations in areas associated with supraliminal induced sexual arousal.     

Repeated questioning for order of events: disparate effects following logical versus random presentation

In the present study, 72 college-age participants from an introductory psychology course viewed a series of 20 pictures depicting events surrounding a routine activity, i.e., eating at a cafeteria; these pictures were presented either in a logical order. e.g., enter cafeteria, pick up tray, stand in line, and select food, or in a random order. Three successive tests of free reconstruction of order indicated disparate effects of these conditions; random presentation produced significant forgetting of order information across tests, whereas logical presentation produced no change in performance across tests. Whereas randomly presented stimuli produced both reliable intertest recovery (reminiscence) and forgetting, neither result was observed following logical presentation. The implications of these data for eyewitness testimony for general theories of hypermnesia are discussed.     

Short-Term Retention of “Surprising” Events By Pigeons

Terry and Wagner (1975) have suggested that the short-term retention of information about an event is enhanced if the occurrence of the event is made unexpected or surprising. Three experiments tested this idea using delayed conditional position (Experiment I) and colour discriminations (Experiments II and III). The subjects were pigeons and the presentation of food was the target event to be remembered. Choice of one of two simultaneously presented stimuli was reinforced if the retention interval had been initiated by presentation of target food. Contrary to Terry and Wagner's claim, retention was superior on probe test trials in Experiments I and II if the presentation of the target food was preceded by a previously established signal for food (CS+) rather than by a stimulus which had not been paired with food (CS-). Experiment III systematically manipulated the signalling conditions used during initial discrimination training. Retention was better following a CS+ presentation if the target food had been signalled during initial discrimination training but worse if the food presentation had been unsignalled. These results do not favour the idea that retention of an event is directly affected by whether or not the target event is surprising.     

Attention level oscillations during visual perception of moving stimuli

Optokinetic nystagmus (OKN) pursuit phase velocity oscillations were studied in seven undergraduates during repeated 4 min presentation of optokinetic stimuli. The following variable parameters of the stimuli motion were used with each subject: horizontal direction, angular velocity (AV), and frequency-to-velocity ratio. AV of the OKN pursuit phases was found to decrease markedly within the first 30 sec of stimuli presentation with its successive increase and variously marked oscillations. Gradual decrease of the AV of OKN pursuit phases was observed at the end of the whole examination as compared to its beginning already within 4 min presentation of the moving stimuli. The results are discussed from the point of view of the arousal, and the activation components of visual attention.     

Visual Attention to Pictorial Food Stimuli in Individuals With Night Eating Syndrome: An Eye-Tracking Study

Night eating syndrome (NES) is characterized by excessive evening and/or nocturnal eating episodes. Studies indicate an attentional bias towards food in other eating disorders. For NES, however, evidence of attentional food processing is lacking. Attention towards food and non-food stimuli was compared using eye-tracking in 19 participants with NES and 19 matched controls without eating disorders during a free exploration paradigm and a visual search task. In the free exploration paradigm, groups did not differ in initial fixation position or gaze duration. However, a significant orienting bias to food compared to non-food was found within the NES group, but not in controls. A significant attentional maintenance bias to non-food compared to food was found in both groups. Detection times did not differ between groups in the search task. Only in NES, attention to and faster detection of non-food stimuli were related to higher BMI and more evening eating episodes. The results might indicate an attentional approach-avoidance pattern towards food in NES. However, further studies should clarify the implications of attentional mechanisms for the etiology and maintenance of NES.     

The interactions of courtship, feeding, and locomotion in the behavioral hierarchy of the snail Helix aspersa

Starvation both increased the number of snails that exhibited feeding (i.e., increased feeding proclivity) and decreased the latencies of response to a food stimulus (i.e., increased food arousal). Feeding inhibited locomotion, although starvation itself had no effect. Sexual arousal (the intensity of courtship) increased locomotion, but only in the absence of a mating partner. Sexual proclivity (the likelihood of a snail to court with conspecifics) had no effect on locomotion. In general, proclivity and arousal had different effects on behavior. Food deprivation did not alter the preference of sexually aroused snails for sexual stimuli over food stimuli Both starved and fed courting pairs responded to a food stimulus only during periods of low sexual arousal, although when not sexually aroused, starved snails usually increased the amount of time they spent in contact with a food stimulus. These results suggest that courtship can suppress feeding and that the expression of feeding behavior is dependent upon the occurrence of low levels of sexual arousal (time sharing).     

Exposure to a rhythmic auditory stimulus facilitates memory formation for the passive avoidance task in the day-old chick.

Previous research regarding the beneficial effects of auditory stimuli on learning and memory in humans has been inconsistent. In the current study, day-old chicks were used to reduce the impact of individual differences on responses. Chicks were trained on a passive avoidance task and exposed to various auditory stimuli. Exposure to a complex rhythmic sequence for 1 min strongly facilitated chicks' long-term memory. The optimal time of presentation of the stimulus was between 10 min before and 20 min after training. Moreover, the enhancing effect was not generalized to the other auditory stimuli tested. It is suggested that this effect may be due to arousal because arousal hormones are critical to long-term memory formation. This study indicates that the temporal characteristics and type of stimulus may be important considerations when investigating the effects of auditory stimuli on cognitive functioning.     

Habituation and dishabituation of female sexual arousal

Measures of subjective and physiological sexual arousal were taken within a session while women either viewed the same segment of erotic film on many occasions or employed the same sexual fantasy over a number of trials. For both film and fantasy there were significant reductions in subjective sexual arousal and average pulse amplitude during the course of repeated erotic stimulation. Subsequent presentation of novel erotic stimuli led to recovery in sexual arousal. Bases for habituation and dishabituation of female sexual arousal are discussed.     

The effects of emotional stimuli on target detection: indirect and direct resource costs

The present study was designed to explore the performance costs of negative emotional stimuli in a vigilance task. Forty participants (20 women) performed a vigilance task in two conditions: one with task-irrelevant negative-arousing pictures and one with task-irrelevant neutral pictures. In addition to performance, we measured subjective state (energetic arousal, tense arousal, task-related and task-unrelated thoughts) and frontal cerebral activity with near infrared spectroscopy. Overall performance in the negative picture condition was lower than in the neutral picture condition and the negative picture condition had elevated levels of energetic arousal, tense arousal and task-related thoughts. Moreover, there was a significant relationship between the impact of the negative pictures on tense arousal and task-related thoughts and the impact of the negative pictures on performance (in comparison to the neutral picture stimuli task). These results provide support for indirect cost models of negative emotional stimuli on target detection performance.     

Acute cortisol elevations cause heightened arousal ratings of objectively nonarousing stimuli

To test the effects of cortisol on affective experience, the authors orally administered a placebo, 20 mg cortisol, or 40 mg cortisol to 85 men. Participants' affective responses to negative and neutral stimuli were measured. Self-reported affective state was also assessed. Participants in the 40-mg group (showing extreme cortisol elevations within the physiological range) rated neutral stimuli as more highly arousing than did participants in the placebo and 20-mg groups. Furthermore, within the 20-mg group, individuals with higher cortisol elevations made higher arousal ratings of neutral stimuli. However, cortisol was unrelated to self-reported affective state. Thus, findings indicate that acute cortisol elevations cause heightened arousal in response to objectively nonarousing stimuli, in the absence of effects on mood.     

Treatment of covert food stealing in an individual with Prader-Willi syndrome

Covert food stealing is common among individuals with Prader-Willi syndrome. We found that verbal reprimands, delivered contingent upon eating prohibited foods, were sufficient to decrease the food stealing of a girl with Prader-Willi syndrome. Warning stimuli were then used to help her discriminate between permitted and prohibited foods during sessions in which food stealing was not directly observed. This procedure resulted in decreases in food stealing from containers labeled with the warning stimuli.