Hamilton, Hiatt-Racer, and Newman (2015) developed a new theory of psychopathy by expanding on Baskin-Sommers et al.‘s attention bottleneck theory and Newman’s response modulation hypothesis, which are theories that predict that psychopathic traits are caused by attention processing deficits. The new theory is basically an expansion of these theories that takes into account all areas of dysregulation associated with psychopathy. Hamilton and colleagues developed this integrative theory by shifting the focus away from specific modules that explain a single deficit at a time, to a systems-level structured approach, which includes affective, cognitive, and neurobiological deficits of psychopathy in a single theory by describing the infrastructure of the neural networks that help the brain to coordinate and bind different types of stimuli and experiences with ongoing goals and motivations and emotions. Other researchers have taken a similar approach to explain schizophrenia and autism. This new theory focuses on general information processing in areas of the association cortex involving the salience, default mode, attentional control, and cognitive control networks.
A neural network is made up of a number of brain regions that are interconnected. Each of these regions is made up of closely grouped interconnected neurons. The neural networks making up the association networks are located in the association portions of the frontal, temporal and parietal cortex of the brain. These networks overlap each other, and each network is involved in a different aspect of cognitive functioning. (In fact, it is fair to say that not everyone agrees on how many neural networks there are or on the exact composition or even the specific functions of each network.) Hamilton and colleagues specifically discuss six different (but related) neural networks.
The salience network is involved in modulating or controlling the activity of other networks during important biological, cognitive, or emotional events. The salience network is concerned with working memory and attentional resources, activating the most important network.
The default mode network is active during times when thought is directed from within and there is no external stimulus, such as examining one’s own thoughts or feelings. This network is inactive during attentional focus or during a goal oriented task.
The attentional control networks include the dorsal and ventral attention networks. The dorsal attention network is activated when a person has a goal or specific expectation; it is also described as a top-down attentional network because it is active when we consciously direct our attention to specific stimuli. The ventral control network is involved with the disengaging and switching of attention and is sometimes described as a bottom-up attentional network because it is active when we suddenly spot something important and shift our attention to it.
The cognitive control networks include the frontoparietal control network, which is involved in goal directed thinking by controlling selective attention and the cingulo-opercular network, which is involved with staying on task. It may also be involved in switching from an internally directed state to a goal directed state.
The brain begins processing information when stimuli coming from the five senses are converted to neural signals that arrive at the primary sensory areas of the cerebral cortex where information is then passed on to adjacent sensory association regions. These adjacent regions are unimodal in that they receive information from only the closest sensory system such as the auditory or visual system. Further from the primary sensory areas and still in the association areas of the cortex, multimodal regions are found. It is here that information from unimodal and other non-sensory regions is integrated, and it is argued that, through this integration, cognition emerges (including the formation of mental representations and the development of thoughts). Processing deficits at any level of integration can interfere with the formation of mental representations.
The modular theories of the past have focused mainly on emotion or information processing deficits. Emotion based theories have focused on the lack of empathy and guilt displayed by an individual with psychopathy. These deficiencies are often hypothesized to arise from an inability to learn from fear or punishment. Among information processing based theories, the most influential is arguably Newman’s own response modulation hypothesis, which has focused mainly on the inability of individuals with psychopathy to shift their attention when salient information is peripheral to their current task. These deficiencies are hypothesized to arise from cognitive deficits. Theories on affective deficits fail to fully explain information processing deficits. Although some theories that focus on information processing deficits also provide explanations for emotional deficits seen in psychopathic individuals, these theories have yet to integrate the growing evidence on the wide range of brain abnormalities, including structural and connective issues.
Hamilton, Hiatt-Racer and Newman (2015) propose that psychopathy is caused by an inability to become aware of and quickly integrate incoming parts of multi-dimensional stimuli from the senses, causing a person with psychopathy to process information in a sequential manner instead of processing multiple stimuli simultaneously. The difficulty in integration leads to a lack of complete formation of some mental concepts and ultimately leads to the abnormal development of the associative networks.
The authors proposed that the integration deficit of individuals with psychopathic traits is caused by both specific problems in the functioning of two associative neural networks, the salience network and the default mode network, along with a diminished ability of the neural networks to work together. Moreover, they make clear that it appears that the frontoparietal control network continues to function normally in psychopathic individuals.
According to this theory, both brain topography and the environment mold mental processes, motivation, and behavior. Because the frontoparietal control network is functional and because it has the ability to engage other networks, it is likely that cognitive processing deficits of psychopathic individuals will be context-specific and not global. In other words, specific conditions are needed before a deficit will be seen, such as when an individual is in conditions that place substantial demands on attention. Under other conditions such as when not very much attention is demanded, an individual with psychopathic traits is often able to focus on salient information, and may perform tasks without any difficulty.
The authors presented evidence consistent with their theory with respect to the different components that make up the sensory information integration process, including: the combining of multiple streams of stimuli coming from the senses to form mental representations, the combining of mental representations to form more complex representations, the development of associative neural networks, and the development of neural systems.
The impaired integration theory hypothesizes that a deficit in perceptual binding is characteristic of psychopathy. Evidence that is consistent with the theory comes from several different experiments, which tested an individual’s perceptual load in different ways. In one experiment participants were asked to memorize a group of neutral and emotional words and were then asked to recall the words. Next they were given an unexpected test to see if they remembered any contextual features such as the color of the words given in the memory task. Those individuals with psychopathic traits showed deficits when they were asked to recall the peripheral stimuli – that is when specific instructions were not given to attend to specific peripheral stimuli, indicating a limited processing ability. In short, these results suggest that individuals with psychopathy may miss emotional cues that are not central to their focus due to a deficit in the perceptual binding of complex stimuli.
The theory proposes that perceptual binding deficits cause stimuli to be processed in a sequential manner and, because of this, underdeveloped mental representations are formed. Over time these underdeveloped representations can have an additive effect causing disruptions in associative processing, such as difficulty in linking past representations with present mental representations for learning. Evidence for this kind of impairment comes from several different experiments that tested an individual’s ability to passively avoid punishment by learning to associate an aversive stimulus to a particular response. The inability of individuals with psychopathy to link present and past mental representations may cause them to fail to learn from their experiences and consequently render them unable to adjust their behavior.
The theory also proposes that underdeveloped mental representations that are formed may set off a domino affect, causing the underdevelopment of connections between certain networks to occur. The sequence in which the brain matures is normally thought to allow for the development of the frontoparietal control network and the dorsal attention network connections to develop first followed by connections between the other association networks. It is thought that the connections between the frontoparietal control network and the dorsal attention network develop normally in individuals with psychopathy, whereas the connections that form between the other association networks are relatively underdeveloped. While the evidence cited to support this hypothesis comes from a scant number of studies employing a specific kind of analysis of neuroimaging data (a method called graph theoretical analysis), one preliminary study found that, in psychopathic offenders, there was a decrease in functional connections between neural networks, as well as other brain abnormalities.
The theory submits that neural systems, which include a number of neural networks, are shaped by experience and that experience is shaped in turn by neural systems. Impaired integration may cause individuals with psychopathy to have problems developing neural networks and the connections between them, and ultimately this could obstruct the development of certain neural systems, such as the ones involved with empathy, attention or language. Evidence to support impaired connectivity between neural networks relating to empathy comes from many studies including several examining moral reasoning. The salience network is thought to control the switching between the default mode network and the frontoparietal control network, and during a moral reasoning task a normal individual will have more activity in the default mode network, while individuals with psychopathy will have less activity in this network. Less activity in the default mode network during moral reasoning correlates with a utilitarian mindset, in that the best moral choice is one that helps the most people. Evidence to support impaired connectivity between neural networks relating to attention also comes from many studies including several that looked at the dynamics between the dorsal and ventral attention networks where attention is either driven by current goals or by salient information. Individuals with psychopathy have trouble switching their attention to salient stimuli when these stimuli are not their central focus.
The Impaired Integration theory has advanced the understanding of psychopathy by applying a systems level approach to explain the different deficits seen in psychopathic individuals. In doing this, the researchers have built a framework that merges affective and cognitive perspectives, as well as takes into account neurobiological abnormalities seen in offenders with psychopathic traits, together in a single theory. With this framework in place, it will serve to guide future research in the determination of the overall underlying cause or causes for the impairments seen. The researchers suggest that future studies should be conducted to determine whether attentional deficits are the cause or the result of neural connectivity deficits and to examine whether hormonal abnormalities worsen this situation. They also suggest examining biochemical factors to see what affect such factors have on communication between neural networks, as well as exploring the possibility of whether individuals with psychopathic traits are able to improve their brain function (and their cognitive and emotional processing) through the conscious employment of deliberate effort in processing stimuli.
To learn more about the Impaired Integration Theory you can read:
Hamilton, R. K. B., Racer, K. H., & Newman, J. P. (2015). Impaired integration in psychopathy: A unified theory of psychopathic dysfunction. Psychological Review, 122, 770-791.
Newman, J. P., Patterson, C. M., & Kosson, D. S. (1987). Response perseveration in psychopaths. Journal of Abnormal Psychology, 96, 145-148.
Baskin-Sommers, A. R., Curtin, J. J., & Newman, J. P. (2013). Emotion-modulated startle in psychopathy: Clarifying familiar effects. Journal of Abnormal Psychology, 122, 458-468.
Written by Sandra Michels and the Research Committee