What we perceive depends critically on what/how we feel and behave, and vice versa. Accordingly, the affective state and environmental context interactively modulate information processing. Both the picture viewing and threat-of-shock paradigms have been shown to reliably activate motivational systems organizing perceptual, physiological and behavioral responses. However, recent research just began to investigate the differences and commonalities of both manipulations (Bradley et al., 2005; Funayama et al., 2001;
Lissek et al., 2007). For instance, Bradley and colleagues (2005) instructed pleasant and unpleasant pictures as explicit threat or safety cues. Results showed that ‘pleasant’ threat cues potentiated startle responses similar to defensive activation by passively viewing unpleasant pictures. Thus, verbally instructed threat-contingencies were easily acquired regardless of previous hedonic associations. Similarly, Lissek and colleagues (2007) observed a strong impact of rather one-word instructions (enhance, maintain, suppress emotional responses) on startle reflex modulation elicited by means of threat-of-shock and affective picture content. As a result, emotion regulation modulated defensive startle reflex magnitude linearly (suppress < maintain < enhance) in both experimental manipulations.
Finally, regarding neural substrates involved in emotional picture viewing and threat-of-shock, Funayama and colleagues (2001) reported impaired modulation of fear responding due to instructed threat in patients with left unilateral temporal lobectomy (LTL) but not in patients with right temporal lobe damage. The opposite pattern of startle modulation was observed when participants viewed emotional pictures. Accordingly, neural organization of anticipatory anxiety and emotional picture processing might refer to distinct structures mediating aversive states by means of picture media and instructed real-world danger.
Following the previous pages focusing on anticipatory anxiety, emotion and attention, the main objective of the present thesis is to examine the interaction of
anticipatory anxiety and emotion processing. For this purpose, the threat-of-shock and picture viewing paradigms were integrated. In particular, while viewing emotional/motivational significant and neutral pictures, aversive anticipatory processes were triggered by means of verbal instructions about putative aversive consequences (i.e., receiving electric shocks). Utilizing this approach, the present thesis focused on the participants´ subjective experience, peripheral physiological responses and electrocortical measures during affective stimulus exposure under conditions of safety vs. threat-of-shock.
Study I examined the impact of anticipatory anxiety on peripheral physiological and motor responding during the exposure of affective and neutral pictures. To this end, sustained periods of threat-of-shock and safety were signaled by contextual picture frames.
Self-report data, defensive motor reflexes and electrodermal activity were measured in order to test several hypotheses and predictions:
(1.1) Based on fundamental motivational brain circuits, cues signaling threat of aversive events are suggested to prime defensive response patterns. Firstly, indicating enhanced defensive activation, the eyeblink reflex to auditory startle probes is expected to be potentiated during threat in contrast to safety conditions. Secondly, as an indicator of emotional arousal, the electrodermal activity is predicted to show elevated levels during threat-of-shock as compared to safety conditions. Thirdly, threat of aversive events should be perceived as more aversive than safety conditions.
(1.2) In analogy to real-world threat, the exposure to complex natural picture materials has been observed to modulate defensive reflex activity. According to the motivational priming account, viewing pleasant pictures are suggested to establish an environmental context in which approach behavior is facilitated and defensive
reflexes are inhibited. Conversely, unpleasant or threatening pictures are suggested to prime defensive behavior as reflected by potentiated eyeblink startle reflexes.
(1.3) Based on the replications (1.1 and 1.2), the present threat-of-shock manipulation may be interpreted in terms of enhanced defensive activation, and the interaction with affective modulated startle reflex is examined. The concurrent activation of motivational systems by phasic picture cues and sustained threat signals might operate independently on the defensive startle reflex (e.g., threat potentiation regardless of the concurrently presented picture valence). Alternatively, synergistic interactions might exhibit startle potentiation selectively for unpleasant cues under threat (cf. motivational priming), or for pleasant and neutral cues incongruent to aversive anticipation.
Study II focused on perceptual and attentional processes mutually involved in anticipatory anxiety and affective picture processing. For this purpose, the experimental protocol as utilized in Study I was adapted to the requirements of the ERP technique.
(2.1) The hypothesis that emotionally/motivationally significant stimuli guide selective attention and receive enhanced processing is supported by a large body of behavioral and neuroscientific studies. Accordingly, electrophysiological indicators of preferential emotion processing (EPN and LPP) are expected to be replicated under safety conditions similar to passive viewing conditions in recent research.
(2.2) Extending the notion of preferential emotion processing, the anticipation of aversive events is assumed to modulate emotion-related processing patterns.
According to the motivated attention theory, threat-of-shock might exhibit enhanced EPN or LPP amplitudes for pleasant and unpleasant picture cues.
Alternatively, a motivational priming account would predict selective processing
advantages for unpleasant pictures under conditions of sustained threat-of-shock.
Furthermore, under threatening conditions general sensitization effects might modulate stimulus processing irrespective of picture valence suggested to reflect enhanced vigilance/alertness when confronted with danger signals.
(2.3) Rather exploratory analyses are undertaken to reveal distinct effects of sustained defensive activation on the processing of pleasant, neutral and unpleasant pictures.
Study I and II firstly examined the impact of contextual threat signals on the processing of concurrently presented complex pictures (i.e., not predictive for threat-of-shock). Extending this research, Study III directly manipulated the inherent affective value of the picture materials by means of verbal instructions. In separate runs, pleasant, neutral and unpleasant picture categories were instructed as threat-of-shock or safety cues. That is, each picture category served once as a threat-cue (predictive for threat), safe-cue (predictive for safety), and control cue (no threat-of-shock), respectively.
(3.1) According to (2.1), selective emotion processing as indexed by the EPN and LPP is expected to be replicated under passive viewing (control) condition.
(3.2) A picture category instructed as a safe-cue was presented within a sequential context of threat-of-shock (as cued by a threat-cue category). Thus, the need of fast stimulus identification and efficient extraction of stimulus meaning is important in order to distinguish between safety and shock cues. Differentiating threat- and safe-cues might modulate EPN component indicative for preferential emotion processing. Alternatively, more early ERP components (e.g., P1) implicated in unspecific vigilance might reveal threat-sensitive effects.
(3.3) Furthermore, under threat-cue condition, the attentional focus is directed to the stimulus meaning itself. Explicitly instructing emotional and neutral picture
categories as high-value threat cues might outline similarities and differences in stimulus-driven and task-driven attention processes in the context of aversive anticipation.