Effects of a small talking facial image on autonomic activity: the moderating influence of dispositional BIS and BAS sensitivities and emotions

Abstract

We examined the moderating influence of dispositional behavioral inhibition system and behavioral activation system (BAS) sensitivities, Negative Affect, and Positive Affect on the relationship between a small moving vs. static facial image and autonomic responses when viewing/listening to news messages read by a newscaster among 36 young adults. Autonomic parameters measured were respiratory sinus arrhythmia (RSA), low-frequency (LF) component of heart rate variability (HRV), electrodermal activity, and pulse transit time (PTT). The results showed that dispositional BAS sensitivity, particularly BAS Fun Seeking, and Negative Affect interacted with facial image motion in predicting autonomic nervous system activity. A moving facial image was related to lower RSA and LF component of HRV and shorter PTTs as compared to a static facial image among high BAS individuals. Even a small talking facial image may contribute to sustained attentional engagement among high BAS individuals, given that the BAS directs attention toward the positive cue and a moving social stimulus may act as a positive incentive for high BAS individuals.

Introduction

The aim of this experiment was to examine the moderating influence of dispositional behavioral inhibition system (BIS) and behavioral activation system (BAS) sensitivities (Gray, 1982, Gray, 1991) and affective dispositions on the relationship between a small moving vs. static facial image and autonomic responses when viewing/listening to news messages read by a newscaster. It was hypothesized that a moving facial image would act as a positive incentive for high BAS individuals, thereby eliciting increased attention and engagement as indexed by autonomic nervous system (ANS) parameters, such as respiratory sinus arrhythmia (RSA).

A talking facial image is a social stimulus that captures attention effectively. When presented with a talking facial image, viewers fixate almost exclusively on the eyes or mouth, irrespective of the image size (Munhall and Vatikiotis-Bateson, 1998). A moving image of human face represents a special case of image motion because facial motion plays an important role in human speech communication (de Gelder and Vroomen, 2000, Munhall and Vatikiotis-Bateson, 1998). Given that visual information is sampled from the talker's face, facial movements facilitate speech perception (also called ‘lipreading’ or ‘speechreading;’ de Gelder and Vroomen, 2000, McGurk and MacDonald, 1976). In addition, not only language but also emotions are perceived both by eye and by ear. Information about other people's emotions is obtained from facial expressions, as well as from speech content and prosodic parameters (e.g. pitch and duration; de Gelder and Vroomen, 2000, Ekman, 1992). However, even in the absence of substantial emotional expressions, the structure of the face attracts the gaze of the human infant, for example (Morton and Johnson, 1991).

The engaging quality of moving facial images is also indicated by media research. For example, a considerable body of evidence suggests that people tend to engage in a parasocial interaction when watching a television personality (e.g. Horton and Wohl, 1956, Rubin and McHugh, 1987). That is, they tend to ignore the mediated nature of a television personality, incorrectly perceive he or she as a social actor, and respond to social cues he or she provides just as they would in nonmediated communication. This phenomenon is also intensified by direct address, e.g. a news anchor speaks directly to the camera and therefore, apparently, the viewer (Lombard and Ditton, 1997). Relevant to the present issue, social interactions as such may be arousing owing to involvement and enthusiasm (e.g. Warner and Strowman, 1995). Parasocial interaction is also one aspect of the so-called presence phenomenon, i.e. the perceptual illusion that a mediated experience is not mediated (Held and Durlach, 1992, Lombard and Ditton, 1997). Although a complete sense of presence may be elicited only by emerging technologies, such as virtual reality, more traditional media offer a lesser degree of presence as well (Lombard and Ditton, 1997, Steuer, 1995). Media presentations that engender a greater sense of presence have been suggested as often eliciting greater physiological arousal (at least when the message content is arousing), engagement, and attention (real-world stimuli, or stimuli that are perceived more or less as such, are likely to elicit greater attentional engagement compared to stimuli that are readily perceived as mediated presentations of real-world stimuli; Lombard and Ditton, 1997, Pugnetti et al., 2001). Given the aforementioned facts, a moving facial image presented on the television screen or screen of new telecommunication devices, together with the audio message, may contribute to the perceptual illusion of nonmediation and the illusion that the media personality is a social actor, as well as to concomitant increased engagement and attention.

Although the psychophysiological effects of facial image motion in connection with spoken messages (i.e. messages in the audio channel) have been examined only in one study (Ravaja, submitted for publication), several studies have recently shown that the relationship between stimulus content and emotion-related subjective and physiological responses may be modulated by the formal properties of stimulus presentation (e.g. Detenber and Reeves, 1996, Reeves et al., 1999, Simons et al., 1999). Motion per se has emerged as one important formal presentation attribute that may significantly influence people's emotional responses to the content of pictorial stimuli. Motion is a defining characteristic of film, video, and new communication technologies (e.g. multimedia; Detenber et al., 1998). Apparently, the ecological validity of moving pictorial stimuli is greater as compared to still pictures. Studies comparing the effects of moving and still versions of emotion eliciting images (shown for 6 s) have suggested that image motion is associated with increases in self-reported arousal and electrodermal activity (EDA), particularly when the image content is highly arousing (Detenber et al., 1998, Simons et al., 2000, Simons et al., 1999). Likewise, image motion has been associated with sustained cardiac deceleration and greater cortical activation, as measured by alpha frequency of the electroencephalogram (EEG), that is indicative of orienting or heightened attention (Reeves et al., 1985, Simons et al., 1999).

In a previous study by Ravaja (submitted for publication), the emotional and other effects of facial image motion were examined. That is, the study compared the modulating influence of a moving vs. static facial image on emotion- and attention-related subjective and physiological responses to news messages read by a newscaster. It was found that a talking facial image was associated with lower zygomatic and orbicularis oculi electromyographic activity and with decreased RSA, suggesting that a talking facial image captured more attentional resources. A moving facial image resulted also in improved memory performance, but only for positive messages. However, although a moving facial image was associated with high self-reported arousal, it was not associated with physiological arousal as measured by EDA.

It is possible that there are important individual difference variables, i.e. moderator variables, that might affect the nature and magnitude of relations between a moving facial image and physiological responses. Dispositional BIS and BAS sensitivities are such potential moderators. According to Gray, 1982, Gray, 1991, these two primary brain motivational systems underlie behavior and affect (see also Pickering and Gray, 1999). The BIS regulates aversive motivation and controls the experience of anxiety in response to anxiety-relevant cues. It is sensitive to signals of punishment, nonreward, and novelty, and is associated with increased arousal and attention toward the negative cue. The BAS regulates appetitive motivation, and responds to signals of potential reward and nonpunishment by activating approach behavior, increasing arousal, and directing attention toward the positive cue (Gray, 1982, Gray, 1991, Pickering and Gray, 1999). Gray holds that greater BAS sensitivity is also reflected in greater proneness to experience positive feelings when the individual is exposed to cues of impending reward. Carver and White (1994) developed the BIS/BAS scales to measure BIS sensitivity and three aspects of BAS sensitivity, viz., (a) striving for desirable ends (i.e. Drive), (b) positive responses to the occurrence or anticipation of reward (i.e. Reward Responsiveness), and (c) a tendency to seek out new potentially rewarding experiences (i.e. Fun Seeking). Heart rate (HR) is strongly associated with BAS activity (e.g. Fowles, 1980).

The potential moderating influence of BAS activity on the relationship between a moving image of human face and psychophysiological responses is supported by the following facts. Humans are social beings who have an appetitive motivation for social interaction (social relationships are intrinsically rewarding; Aitken and Trevarthen, 1997). Individuals with high BAS sensitivity are likely to direct their attention toward, and respond more strongly to, cues of forthcoming social interaction (i.e. a positive incentive). Recall also that Gray's BAS (or impulsivity) dimension is closely aligned (30°) with extraversion, the essential feature of which is the tendency to enjoy social situations (Lucas and Diener, 2001, Matthews and Gilliland, 1999). As noted above, a moving image of human face is an engaging social stimulus that may also contribute to the illusion that the media personality is a social actor (see Lombard and Ditton, 1997). Thus, a moving facial image may act as an appetitive stimulus; and high BAS individuals are expected to respond more strongly to, and exhibit stronger engagement in, a moving facial image as compared to a still facial image, for example. A moving facial image might be a positive incentive for high BAS individuals also because movement as such is stimulating; recall that high BAS activity underlies the expression of the sensation seeking trait. Relevant to this, high sensation seekers have been suggested as using TV to enhance the intensity, novelty, and complexity of available stimulation (Rowland et al., 1989).

Negative Affect and Positive Affect are the basic dimensions of emotional experience in the model presented by Watson and Tellegen (1985). The self-report Negative Affect and Positive Affect dimensions have been suggested to represent the subjective components of the withdrawal-oriented BIS and approach-oriented BAS, respectively (e.g. Watson et al., 1999, Gray, 1991). These affective dimensions are not synonymous with the broader motivational systems of withdrawal and approach, however. First, in addition to withdrawal-oriented fear (i.e. an apparent manifestation of the BIS), Negative Affect comprises anger that may be a manifestation of a third system, i.e. the fight/flight system (Gray, 1991), and may even be considered as an approach-oriented emotion. Second, as noted above, in addition to the affective manifestations, the BIS and BAS have other important manifestations in terms of the withholding or creation of overt behavior. Third, trait Negative Affect and Positive Affect have also been suggested to roughly correspond to the personality factors of anxiety/neuroticism and extraversion, respectively (Meyer and Shack, 1989); although these personality factors are closely aligned with the BIS and BAS dimensions, they are not synonymous with the latter ones. Given the aforementioned facts, dispositional Negative Affect and Positive Affect were also included as potential moderator variables when examining the facial image motion-physiological responses relation. In general, it would be expected that the effects of these affective dimensions are rather similar to those of the BIS and BAS dimensions, however.

In view of the above considerations, the aim of the present investigation was to explore the potential moderating influence of the aforementioned individual difference variables (i.e. dispositional BIS and BAS sensitivities, Negative Affect, and Positive Affect) on the relationship between a moving facial image and autonomic responses when viewing/listening to financial news messages from a (simulated) pocket PC with a small screen. It was also asked whether the individual difference variables interact with the pleasure and arousal of the message contents in predicting autonomic responses (although this was not the main focus of the study). Examining these issues may (a) increase our understanding of the emotion- and attention-related psychophysiological responses elicited by a moving social stimulus (i.e. human face) and (b) shed light on how to improve media communication to audiences.

In the current study, several measures indexing ANS activity were included: (a) RSA, (b) low-frequency (LF) component of heart rate variability (HRV), (c) pulse transit time (PTT), and (d) EDA. RSA (i.e. respiratory-locked oscillations in HR) is a noninvasive index of parasympathetic nervous system (PNS) function (Berntson et al., 1997, Porges, 1991). High baseline level of RSA has been associated with the ability to maintain attention, while RSA is suppressed during states of sustained attention (e.g. Porges, 1991, Weber et al., 1994). Although RSA may also be used to index emotional stress and stress vulnerability (Porges, 1991, Porges, 1995), RSA was mainly used as an index of attention in the present study, given that the present experiment was not particularly stressful. It was hypothesized that RSA would be suppressed during facial image motion among high BAS individuals (and perhaps among high Positive Affect scorers), given that facial image motion would be expected to result in higher attention and engagement among them. It would also be expected that, of the BAS subcomponents, Fun Seeking is the most relevant one in this connection, given that (a) it may be the most important aspect of BAS activity in directing attention toward the positive cue and (b) it is akin to the sensation seeking trait (see above).

LF HRV corresponds, in turn, to blood pressure oscillations occurring around 0.1 Hz (i.e. the Mayer waves), and is jointly modulated by the sympathetic nervous system (SNS) and the PNS (see Berntson et al., 1997). However, the direction of change in LF HRV during psychological tasks is a controversial issue. Mulders and their colleagues have repeatedly found that LF HRV decreases with increasing task-load or mental effort (Mulder et al., 2000). In contrast, several other studies have shown that LF HRV increases during tasks such as the Stroop Color-Word Interference Test (e.g. Delaney and Brodie, 2000, Grillot et al., 1995, Sato et al., 1998). Middleton et al. (1999) found, however, that LF HRV was lower during attentional tasks (i.e. rapid visual information processing and set-shifting tasks) as compared to planning and working memory tasks. That being so, it was hypothesized that also LF HRV would be decreased during facial image motion among high BAS individuals (and perhaps among high Positive Affect scorers), given that facial image motion would be expected to capture attentional resources.

PTT is determined mainly by factors influencing vascular distensibility, including α-sympathetic stimulation (McDonald, 1974), although it may be susceptible to other factors as well (Contrada et al., 1995); α-sympathetic stimulation produces PTT shortening and vasoconstriction. Sensory intake tasks (i.e. attention to external stimuli) have been found to produce reliable skeletal muscle vasoconstriction (Cohen and Johnson, 1977, Williams et al., 1975). PTT has also been shown to shorten during sensory intake tasks (Hodapp et al., 1990, Svebak et al., 1987). Thus, PTT was used as an index of sympathetic activity and attention. It was expected that PTT would be shorter during facial image motion particularly among high BAS scorers (and perhaps among high Positive Affect scorers).

Finally, EDA indexes primary arousal and is innervated entirely by the SNS (Boucsein, 1992). Fowles (1980) three-arousal model suggests that EDA is (positively) related to the activity of the BIS, although inverse associations have even been found (e.g. Keltikangas-Järvinen et al., 1999). The failure to associate EDA with appetitive motivation (i.e. BAS activity) may possibly have been due to ceiling effects (Fowles, 1988). In addition, it is well established that, during perception, EDA is augmented when processing arousing stimuli of either valence (unpleasant/aversive or pleasant/appetitive) compared with stimuli that are low in arousal (Lang et al., 1993). Given that (a) a moving facial image may act as an appetitive stimulus and (b) the BAS responds to cues of impending reward by increasing arousal (Gray, 1982, Gray, 1991), it would be expected that high BAS individuals exhibit an increase in EDA in response to facial image motion.