Alan Pickering

The New Reinforcement Sensitivity Theory: Implications for Personality Measurement

In this article, we review recent modifications to Jeffrey Grays (1973, 1991) reinforcement sensitivity theory (RST), and attempt to draw implications for psychometric measurement of personality traits. First, we consider Gray and McNaughtons (2000) functional revisions to the biobehavioral systems of RST. Second, we evaluate recent clarifications relating to interdependent effects that these systems may have on behavior, in addition to or in place of separable effects (e.g., Corr, 2001; Pickering, 1997). Finally, we consider ambiguities regarding the exact trait dimension to which Grays “reward system” corresponds. From this review, we suggest that future work is needed to distinguish psychometric measures of (a) fear from anxiety and (b) reward-reactivity from trait impulsivity. We also suggest, on the basis of interdependent system views of RST and associated exploration using formal models, that traits that are based upon RST are likely to have substantial intercorrelations. Finally, we advise that more substantive work is required to define relevant constructs and behaviors in RST before we can be confident in our psychometric measures of them.

Abolition of latent inhibition by a single 5 mg dose ofd-amphetamine in man

The performance of healthy volunteer subjects on an auditory latent inhibition (LI) paradigm was assessed following administration of a single oral dose ofd-amphetamine or placebo. It was predicted that a low (5 mg), but not a high (10 mg), dose ofd-amphetamine would disrupt LI. The prediction was supported with left ear presentation of the preexposed stimulus only. When the preexposed stimulus was presented to the right ear the predicted pattern of findings was not obtained. It is concluded that the dopaminergic system is involved in the mediation of LI in man and it is speculated that the interaction between amphetamine dose and ear of presentation of the preexposed stimulus may reflect normally occurring dopaminergic hemisphere asymmetry.

Spatial memory deficits in patients with unilateral damage to the right hippocampal formation

Patients with unilateral temporal lobe damage resulting from intractable temporal lobe epilepsy (TLE, n = 30) or from temporal lobe resection (temporal lobectomy, TLR, n = 47) were investigated on the Nine-box Maze. The task, analogous to the radial arm maze, was designed to compare spatial mapping and working memory theories of the functions of the hippocampus. The task provides measures of spatial, object, working and reference memory, incorporated into a within subjects design. The spatial component was designed to encourage the formation of allocentric rather than egocentric spatial representations. Spatial memory deficits were found (across working and reference memory components) in both TLE and TLR patients with right temporal lobe damage, with intact spatial memory in patients with corresponding left temporal lobe damage. Performance on the matched non-spatial (object) working memory component was equal to healthy controls for all groups. However all patient groups showed a deficit on object reference memory. These findings are discussed in relation to the underlying temporal lobe pathology and particularly atrophy of the hippocampal formation. Overall, the results support the cognitive mapping theory of hippocampal function, with the demonstration of a selective (and probably allocentric) spatial memory deficit in patients with right hippocampal damage.

Relation between cognitive dysfunction and pseudobulbar palsy in amyotrophic lateral sclerosis.

OBJECTIVES: To examine the relation between cognitive dysfunction and pseudobulbar features in patients with amyotrophic lateral sclerosis (ALS). METHODS: The performance of two patient groups, ALS with pseudobulbar palsy (n = 24) and ALS without pseudobulbar palsy (n = 28), was compared with 28 healthy age matched controls on an extensive neuropsychological battery. Tests used were the national adult reading test, short form of the WAIS-R, recognition memory test, Kendrick object learning test, paired associate learning, Wisconsin card sorting test, verbal fluency, Stroop and negative priming tests, a random movement joystick test, and a computerised Tower of Hanoi test. RESULTS: Tests of executive function showed a pronounced deficit on written verbal fluency in both ALS groups in comparison to controls, which tended to be more prominent in patients with ALS with pseudobulbar palsy. The random movement joystick test (a non-verbal test of intrinsic movement generation) showed an impairment in the generation of random sequences in patients with pseudobulbar palsy only. The computerised Tower of Hanoi showed a subtle planning impairment (shorter planning times) in all the patients with ALS compared with controls on trials requiring more complex solutions. In addition the pseudobulbar patients displayed shorter planning times on complex trials, and tended to solve these trials less accurately. There was also evidence of a deficit for all patients with ALS in comparison with controls on total errors and number of categories achieved on the Wisconsin card sorting test and a strong tendency towards an impairment on a task of selective attention and cognitive inhibition (negative priming). A word recognition memory deficit was showed across both ALS groups. CONCLUSIONS: This study elicited cognitive deficits (involving predominantly executive processes, with some evidence of memory impairment) in patients with ALS and further strengthened the link between ALS and frontal lobe dysfunction, this being more prominent in patients with pseudobulbar palsy. However, cognitive impairments suggestive of extramotor cortical involvement were not exclusive to this subgroup.

Location of lesions in Korsakoff's syndrome: neuropsychological and neuropathological data on two patients.

Psychometric and neuropathological findings on two Korsakoff amnesics are described. Both patients showed anterograde and retrograde amnesia, poor performance on the Peterson short-term memory task, on the Wisconsin card sort test and on certain visuo-spatial tasks. Patient J.W. performed consistently worse on tests of anterograde, but not retrograde amnesia, whereas patient B.C. showed more perseverative difficulties and, unlike J.W., his measured intelligence seemed to have declined from its premorbid level. Both patients showed marked neuronal loss from the medial mammillary bodies and a narrow band of gliosis in the medial thalamus, adjacent to the wall of the third ventricle, a region known as the paratenial nucleus. Only B.C. showed visible signs of cortical atrophy. Morphometric measures did, however, reveal reduced nucleolar volumes in layers III and V of the frontal cortex, with B.C. also showing more marked neuronal loss from these layers. B.C. also showed neuronal loss from the CA1 region of the hippocampus and reduced nucleolar volumes in the septum. Significantly, both patients had normal neuronal numbers and nucleolar volumes in the nucleus basalis of Meynert. J.W. only showed greater dysfunction than B.C. in one region: the locus caeruleus. This finding was related to his more severe amnesia.

Is Organic Amnesia Caused by a Selective Deficit in Remembering Contextual Information

An influential view of amnesia is that the recognition and recall failure is a consequence of a selective loss of memory for contextual, rather than target, information. The various forms of this viewpoint are outlined and one is considered in more detail. This hypothesis claims that amnesics suffer from a selective inability to remember background context i.e. spatiotemporal or extrinsic context. The evidence cited in support of this hypothesis is then critically reviewed and assessed in relation to two methodological problems. The first problem shows that when weak amnesic memory is compared with good normal memory qualitative differences in contextual memory may arise artefactually. The second problem is that contextual memory deficits, found in amnesics, may be incidental consequences of frontal cortex damage rather than essential to the core memory deficit. In the light of these problems it is concluded that currently there is no convincing support for the contextual memory deficit hypothesis of amnesia. Finally, guidelines are laid down which should enable the hypothesis to be more appropriately assessed, and an alternative kind of hypothesis is briefly outlined.

Attentional bias in obsessional compulsive disorder

To date, studies of information processing in anxiety disorders have suggested that the latter are characterised by vigilance for threatening stimuli, possibly specific to personally relevant threat content. The present study represents an attempt to establish whether patients suffering from Obsessional Compulsive Disorder (OCD), generally classified as an anxiety disorder, show a similar cognitive bias. Thus, a replication of MacLeod, Mathews and Tatas (1986) study [Journal of Abnormal Psychology, 95, 15-20] is reported, employing modified materials of direct concern to the OCD subjects i.e. Contamination-related words. The results did indeed reveal content specific vigilance, whereby the OCD group were more vigilant for contamination content than mood-matched High Trait Anxious (HTA) controls, but the reverse was true for Social Anxiety words. Additionally, while a general threat interference effect was identified for both OCD and HTA subjects this was not content specific. A second experiment employing Low Trait Anxious subjects revealed no vigilance for threat nor any threat interference in this sample. The clinical implications and possible mechanism underlying these results are discussed.

Disrupting feedback processing interferes with rule-based but not information-integration category learning.

The effect of a sequentially presented memory scanning task on rule-based and informationintegration category learning was investigated. On each trial in the short feedback-processing time condition, memory scanning immediately followed categorization. On each trial in the long feedbackprocessing time condition, categorization was followed by a 2.5-sec delay and then memory scanning. In the control condition, no memory scanning was required. Rule-based category learning was significantly worse in the short feedback-processing time condition than in the long feedback-processing time condition or control condition, whereas information-integration category learning was equivalent across conditions. In the rule-based condition, a smaller proportion of observers learned the task in the short feedback-processing time condition, and those who learned took longer to reach the performance criterion than did those in the long feedback-processing time or control condition. No differences were observed in the information integration task. These results provide support for a multiple-systems approach to category learning and argue against the validity of single-system approaches.

Personality and reinforcement in associative and instrumental learning

A two-stage (associative and instrumental) learning task was developed to examine the role of personality in mediating: (1) the development of appetitive and aversive CS-UCS associations; and (2) passive avoidance of aversive CSs, and approach to appetitive CSs, in instrumental learning. The results showed: (1) that harm avoidance [as measured by the Tridimensional Personality Questionnaire (TPQ)] predicted aversive CS-UCS associations, while [TPQ] reward dependence predicted appetitive CS-UCS associations (no personality factors predicted neutral CS-UCS associations); and (2) that subjects high in impulsivity [as measured by the IVE scale of the Eysenck Personality Scales (EPS)] showed poor passive avoidance to the aversive-CS, while subjects high in trait anxiety [as measured by the State-Trait Anxiety Inventory (STAI)] showed poor approach behaviour to the appetitive-CS. A correlational study with TPQ and Eysenck Personality Questionnaire [EPQ] factors revealed the structural comparability of these two descriptive systems. The results suggest that associative and instrumental learning under appetitive and aversive conditions do not reflect a general (arousal-based) learning factor, and that specific personality factors mediate reward and punishment in the two stages of learning. The findings are discussed in relation to Eysencks, Grays, Cloningers, and Newmans models of personality.

Damage to the Salience Network and Interactions with the Default Mode Network

Interactions between the Salience Network (SN) and the Default Mode Network (DMN) are thought to be important for cognitive control. However, evidence for a causal relationship between the networks is limited. Previously, we have reported that traumatic damage to white matter tracts within the SN predicts abnormal DMN function. Here we investigate the effect of this damage on network interactions that accompany changing motor control. We initially used fMRI of the Stop Signal Task to study response inhibition in humans. In healthy subjects, functional connectivity (FC) between the right anterior insula (rAI), a key node of the SN, and the DMN transiently increased during stopping. This change in FC was not seen in a group of traumatic brain injury (TBI) patients with impaired cognitive control. Furthermore, the amount of SN tract damage negatively correlated with FC between the networks. We confirmed these findings in a second group of TBI patients. Here, switching rather than inhibiting a motor response: (1) was accompanied by a similar increase in network FC in healthy controls; (2) was not seen in TBI patients; and (3) tract damage after TBI again correlated with FC breakdown. This shows that coupling between the rAI and DMN increases with cognitive control and that damage within the SN impairs this dynamic network interaction. This work provides compelling evidence for a model of cognitive control where the SN is involved in the attentional capture of salient external stimuli and signals the DMN to reduce its activity when attention is externally focused.