Attentional processes play an important role in the fear deficit of psychopathic individuals. According to the response modulation theory, psychopathic individuals appear insensitive to fear-related stimuli because they fail to reallocate attention to secondary affective information while engaged in goal-directed behavior (MacCoon, Wallace, & Newman, 2004
; Patterson & Newman, 1993
). This difficulty balancing the demands of goal-directed processing and secondary information processing creates a bias whereby psychopathic individuals are less responsive to affective information unless it is a central aspect of their goal-directed focus of attention.
We previously used an instructed fear-conditioning task to demonstrate that the fearlessness of psychopathic offenders is moderated by their focus of attention (Newman, Curtin, Bertsch, & Baskin-Sommers, 2010
). Fear-potentiated startle (FPS) was measured as participants categorized colored letter stimuli under three conditions. One condition required participants to respond on the basis of the threat-relevant aspect of the stimuli (i.e., the color that predicted electric shocks). Two other conditions required participants to respond on the basis of an alternative, threat-irrelevant aspect of the stimuli (i.e., the case of the letter or the match or mismatch in a two-back task). In the alternative-focus conditions, the threat-relevant information was outside the primary focus of goal-directed behavior. Psychopathy scores (as measured by the Psychopathy Checklist-Revised, PCL-R; Hare, 2003
) were significantly inversely related to FPS under conditions that required participants to focus on a threat-irrelevant dimension of stimuli. In contrast, psychopathy scores were unrelated to FPS in the condition that focused attention on the threat-relevant dimension. These results are consistent with the proposal that psychopathy involves abnormalities in attention that undermine sensitivity to emotion-related cues that normally modulate goal-directed behavior.
Although this research provided some of the strongest evidence to date that the fear deficit of psychopathic individuals is moderated by attention, the study did not specify the attentional mechanism underlying this effect. Goal-directed behavior requires attention to focus on relevant stimuli and ignore potential distractors. However, the mechanism for such goal-relevant control may vary depending on the demands of a specific situation, and it may involve diverse neural and cognitive systems. A useful framework for understanding the different types of attentional selection emanates from cognitive neuroscience research on the locus of attentional selection (Driver, 2001
; Knudsen, 2007
; Luck & Hillyard, 1999
). Within this framework, attentional selection and attentional limitations may occur as a function of filtering prior to stimulus identification (early stage) or as a function of engagement of higher-order cognitive processes after stimulus identification (later stage). Depending on task demands, attentional selection and attentional limitations may also occur at multiple loci of selection (multilocus selection).
Early stages of selective attention occur as a function of a bottleneck that, once established, blocks the processing of secondary information that is not goal relevant (Driver, 2001
). Although this bottleneck is most commonly associated with perceptual load (Lavie, Hirst, de Fockert, & Viding, 2004
), there is also evidence that preperceptual filtering may be based on features such as spatial location or visual properties available prior to stimulus identification (Luck & Hillyard, 1999
). Such early attentional influences can affect neural activity in the visual cortex (Kastner & Ungerleider, 2000
), filter the processing of sensory information (Hillyard, Vogel, & Luck, 1998
), and prevent the perception of secondary information (Lavie et al., 2004
). Thus, for psychopathic individuals, once the distinction between primary and secondary information is established, the bottleneck filter may limit the processing of secondary information, such as salient threat stimuli.
Selective attention may also operate at a later, postperceptual stage (e.g., Luck & Hillyard, 1999
). At some point between the occurrence of a stimulus and its effect on behavior, stimulus-driven and goal-relevant information compete for representation, selection, and control (Desimone & Duncan, 1995
). At this later stage, selection occurs as a function of higher-order cognitive processes, such as memory and response selection, which signal the importance of specific information (Deutsch & Deutsch, 1963
; Lavie et al., 2004
). Thus, it is also possible that psychopathic individuals initially perceive and identify both primary and secondary information but are particularly adept at using higher-order processes to resolve the competition between goal-relevant and secondary demands on attention.
Although these early- and later-stage influences on selective attention occur at different points in the processing stream and involve activation of different brain regions (Hillyard & Anllo-Vento, 1998
; Knudsen, 2007
; Vogel, Woodman, & Luck, 2005
), the processes underlying these influences may also overlap and combine to influence information processing (Luck & Hillyard, 1995
). That is, selective attention may act at multiple stages of processing (Yantis & Johnston, 1990
), with the ultimate effect on information processing being influenced by diverse situational and individual difference variables (multilocus selection; Awh, Vogel, & Oh, 2006
; Lavie et al., 2004
). Of particular relevance to this research is the notion that the early attention bottleneck may not always be triggered in an automatic, bottom-up way, but at times may be contingent on whether information and task attributes match a person's task-relevant set (e.g., attributes based on task instructions; Corbetta, Miezin, Dobmeye, Shulman, & Petersen, 1991
; Folk, Remington, & Johnston, 1992
). In addition, cognitive processes such as working memory may affect the on-line representation of set-relevant information (Awh et al., 2006
; Haenny & Schiller, 1988
). Therefore, a person's ability to perform this type of multilocus selection may be influenced by individual differences in working memory capacity (Fukuda & Vogel, 2009
). Within a multilocus model, it is possible that the psychopathy-related attentional bias relates fundamentally to an early attention bottleneck, but that in contexts that require the application of a set (i.e., a specific goal-directed focus), working memory capacity is important for maintaining that bottleneck and precluding the processing of secondary information. Overall, the distinction between these stages of attentional selection provides a valuable framework for specifying the attention-related deficits of psychopathic individuals.
The primary aim of the present study was to specify the attentional abnormalities that undermine the processing of secondary affective stimuli in psychopathy and its associated factors. To this end, we modified the task we previously used (Newman et al., 2010
) so that the threat information (color) and threat-irrelevant information (letter) were temporally separated (Mitchell, Richell, Leonard, & Blair, 2006
). Specifically, we examined FPS in a new sample of incarcerated offenders under four experimental conditions that crossed threat versus alternative (i.e., threat-irrelevant) focus of attention with early versus late presentation of the threat-relevant cues. This manipulation yielded four conditions: early alternative focus, late alternative focus, late threat focus, and early threat focus. Of particular importance for testing our hypothesis is the fact that the experimental manipulation allowed us to examine FPS under two alternative-focus conditions. The first engaged the alternative focus of attention at an early stage, prior to the presentation of threat-relevant information (i.e., the early-alternative-focus condition). The second presented threat-relevant information prior to establishing the alternative focus of attention, thereby increasing demands for higher-order processes to select and maintain a set-congruent focus (i.e., the late-alternative-focus condition).
The following three hypotheses were developed to specify the attentional processes that moderate emotion processing in psychopathic individuals. First, to the extent that their deficit in response modulation involves an early attention bottleneck, psychopathic offenders should display deficient FPS, particularly when attention (i.e., goal-directed behavior) is engaged prior to presentation of the threat-relevant information (early-alternative-focus condition). Second, to the extent that their insensitivity to threat-related stimuli is inherently a reflection of a later stage of selection, psychopathic offenders' FPS deficit should be especially apparent under circumstances that necessarily call for higher-order processing (i.e., when the threat-relevant information is presented prior to the goal-relevant information; late-alternative-focus condition). Third, psychopathy-related differences in FPS may be moderated by working memory capacity, particularly in the late-alternative-focus condition, which requires the maintenance of an attentional set in the absence of set-relevant information to support the early attention bottleneck (i.e., multilocus selection). Because some researchers advocate parsing psychopathy into two components (Factor 1 and Factor 2; Patrick, 2007
), we also examined the association between the two major psychopathy factors and FPS in this experimental design.