Tailored testing for selection and allocation

The view is proposed that where conditions for psychological testing are favourable the nature of the conventional pencil-and paper group test sets a limit on the quality of assessment achievable. This is so because it insists on standardisation through uniformity. This procrustean template is a handicap to the assessment of the non-modal man. Selection and allocation in the Army is a favourable testing situation - centralised, stable and with high volume. Tailored testing is an alternative to conventional testing that allows variation to suit the ability of the person being assessed. The present thesis proposes and tries out a tailored testing procedure aimed at selection and allocation in the Army and other like circumstances. The research review shows tailored testing to be a post-war interest with statistical antecedents in many non-psychological areas. In the last five years research has grown rapidly, stimulated by the increasing possibilities of online computer-assisted testing. A tailored testing procedure is proposed that makes few assumptions, makes full use of prior information, conducts a test item by item, and reports its outcome in decision risk terms. The aim is for a coping procedure without critical item requirements. Real-data simulations are carried out using a large sample of recruits' answers to vocabulary items. An independent conventional verbal test provides a basis for item calibration. The procedure uses two novel Indices of item performance concerned with the tails of the empirical item characteristic curves and their interaction with the normative recruit distribution of verbal attainment. These indices are held to be more relevant to effective convergence of the tailoring process. Good accuracy of convergence is demonstrated by the procedure, and savings in test length for the average recruit as well as greater savings for the non-average. Empirical studies are needed to investigate the temporal dimension of tailored testing

Dissociation of prefrontal cortex and nucleus accumbens dopaminergic systems in conditional learning in rats

There is converging evidence that the prefrontal and mesolimbic dopaminergic (DAergic) systems are involved in the performance of a variety of tasks that require the use of contextual, or task-setting, information to select an appropriate response from a number of candidate responses. Performance on tasks of this nature are impaired in schizophrenia and in rats exposed to psychotomimetics; impairments that are often attenuated by administration of dopamine (DA) antagonists. Rats were trained on either a complex instrumental discrimination task, that required the use of task-setting cues, or a simple discrimination task that did not. Following training, microdialysis probes were implanted unilaterally in either the medial prefrontal cortex (mPFC) or nucleus accumbens (NAc) and samples were collected in freely moving animals during a behavioural test session. In Experiment 1, we found no difference in levels of DA in the mPFC of rats while they were performing the two discrimination tasks. Rats that performed the complex task did, however, show significantly higher mPFC DA levels relative to rats in the simple discrimination condition following the end of the behavioural test session. In Experiment 2, rats performing the conditional discrimination showed lower levels of DA in the NAc compared to the simple discrimination group both during the test session and after it. These results provide direct evidence that conditional discrimination tasks engage frontal and mesolimbic DAergic systems and are consistent with the proposal that regulation of fronto-striatal DA is involved in aspects of cognitive control that are known to be impaired in individuals with schizophrenia

Effect of low-intensity treadmill exercise on behavioural measures and hippocampal parvalbumin immunoreactivity in the rat

Exercise has been demonstrated to have positive effects on both the body and brain. The present study aimedtodeterminethebehaviouralandmorphological consequenceoflow-intensityrunning.Ratswere exercised on a treadmill for a total of 30days, 30min/day. Social interaction, locomotor activity and behaviour on an elevated plus maze were assessed post-treatment. Exercised animals demonstrated morepassiveinteractionandless timenotinteractingthancontrol animals thatwerenotexercised.Conversely, locomotor and anxiety measures showed no effect of exercise. Analysis of brains demonstrated an increase in expression of parvalbumin immunoreactive neurons in the hippocampus localised to the CA1 and CA2/3 regions. These results demonstrate thatlow-intensity exercise leads to changes in social behaviour as well as neuroplastic morphological changes within the hippocampus

Punishment insensitivity emerges from impaired contingency detection, not aversion insensitivity or reward dominance

© 2019, eLife Sciences Publications Ltd. All rights reserved. Our behaviour is shaped by its consequences – we seek rewards and avoid harm. It has been reported that individuals vary markedly in their avoidance of detrimental consequences, i.e. in their sensitivity to punishment. The underpinnings of this variability are poorly understood; they may be driven by differences in aversion sensitivity, motivation for reward, and/or instrumental control. We examined these hypotheses by applying several analysis strategies to the behaviour of rats (n = 48; 18 female) trained in a conditioned punishment task that permitted concurrent assessment of punishment, reward-seeking, and Pavlovian fear. We show that punishment insensitivity is a unique phenotype, unrelated to differences in reward-seeking and Pavlovian fear, and due to a failure of instrumental control. Subjects insensitive to punishment are afraid of aversive events, they are simply unable to change their behaviour to avoid them

Lesions of the Basolateral Amygdala Disrupt Conditioning Based on the Retrieved Representations of Motivationally Significant Events

This predicts that lesions of the BLA will not produce a decrement in performance in conditioning procedures based on the formation of associations between the sensory aspects of neutral events but will interfere with conditioning based on associations between neutral cues and motivationally significant events. This prediction is supported by the evidence that BLA lesions were without effect on a sensory preconditioning procedure (experiment 1A) that used neutral cues but that BLA lesions did significantly impair representation-mediated conditioning (experiment 1B) when the target cues were motivationally significant at the time of training. These results demonstrate that animals with lesions of the BLA can represent the sensory aspects of neutral events but not the sensory aspects of motivationally significant events

Prefrontal cortex lesions disrupt the contextual control of response conflict

The prefrontal cortex has been implicated in multiple forms of goal-directed behavior. Rats with pretraining lesions to the prefrontal cortex (PFC) or specific lesions to the anterior cingulate cortex (ACC) were trained and tested on a novel behavioral procedure measuring aspects of cue and response competition typical of tests of prefrontal function in humans. Rats were trained on two biconditional discrimination tasks, one auditory and one visual, in two discriminably different contexts. At test, they received presentations of audiovisual compounds of these training stimuli in both contexts, in extinction. These compounds were formed in such way that the individual elements had dictated either the same (congruent trials) or different (incongruent trials) responses during training. Sham-operated rats used the contextual cues to disambiguate the conflicting response information provided by incongruent stimulus compounds. ACC lesions impaired the contextual control of instrumental responding during incongruent cues during only the initial period of cue presentation, whereas larger PFC lesions abolished incongruent cue performance completely. Neither biconditional discrimination acquisition, nor test performance during congruent stimulus compounds, were affected by the lesions. These findings are consistent with human and nonhuman primate studies, indicating a role for the PFC in the processes by which cues come to control behavior in the face of conflicting information and the ACC specifically in processes such as detection of response conflict. This procedure provides a good foundation for an improved understanding of the disruption to goal-directed behavior seen with frontal dysfunction in a number of neuropsychological disorders including schizophrenia

Lesions of the basolateral amygdala disrupt conditioning based on the retrieved representations of motivationally significant events

One recent perspective (Blundell et al., 2001; 2003; Killcross and Blundell, 2002; Balleine et al. 2003) on the function of the basolateral region of the amygdala (BLA) suggests that it plays an important role in the representation of the sensory features of motivationally significant events. This predicts that lesions of the BLA will not produce a decrement in performance in conditioning procedures based on the formation of associations between the sensory aspects of neutral events but will interfere with conditioning based on associations between neutral cues and motivationally significant events. This prediction is supported by the evidence that BLA lesions were without effect on a sensory preconditioning procedure (experiment 1A) that used neutral cues but that BLA lesions did significantly impair representation-mediated conditioning (experiment 1B) when the target cues were motivationally significant at the time of training. These results demonstrate that animals with lesions of the BLA can represent the sensory aspects of neutral events but not the sensory aspects of motivationally significant events

Lesions of the basolateral amygdala disrupt selective aspects of reinforcer representation in rats

The amygdala is known to play a role in learning about motivationally significant events. We investigated this role further by examining the effects of excitotoxic lesions of the basolateral amygdala on the ability of rats to use instrumental outcomes to direct responding (the differential outcomes effect) and on the ability of Pavlovian cues to modulate instrumental performance based on shared outcomes (reinforcer–selective Pavlovian-to-instrumental transfer). We found that basolateral amygdala (BLA) lesions did not affect the ability of rats to learn a basic instrumental conditional discrimination, but did disrupt the ability of differential outcomes to facilitate acquisition. In Pavlovian-to-instrumental transfer, BLA lesions did not disrupt the basic enhancement of instrumental performance but did abolish the reinforcer specificity of that enhancement. These results suggest that the BLA is involved in the representation of the sensory aspects of motivationally significant events

Amphetamine exposure enhances habit formation

Performance of instrumental actions in rats is initially sensitive to postconditioning changes in reward value, but after more extended training, behavior comes to be controlled by stimulus–response (S-R) habits that are no longer goal directed. To examine whether sensitization of dopaminergic systems leads to a more rapid transition from action–outcome processes to S-R habits, we examined performance of amphetamine-sensitized rats in an instrumental devaluation task. Animals were either sensitized (7 d, 2 mg/kg/d) before training (experiment 1) or sensitized between training and testing (experiment 2). Rats were trained to press a lever for a reward (three sessions) and were then given a test of goal sensitivity by devaluation of the instrumental outcome before testing in extinction. Control animals showed selective sensitivity to devaluation of the instrumental outcome. However, amphetamine sensitization administered before training caused the animals’ responding to persist despite the changed value of the reinforcer. This deficit resulted from an inability to use representations of the outcome to guide behavior, because a reacquisition test confirmed that all of the animals had acquired an aversion to the reinforcer. In experiment 2, post-training sensitization did not disrupt normal goal-directed behavior. These findings indicate that amphetamine sensitization leads to a rapid progression from goal-directed to habit-based responding but does not affect the performance of established goal-directed actions

Competing contextual processes rely on the infralimbic and prelimbic medial prefrontal cortices in the rat

Ambiguous relationships between events may be established using interference procedures such as latent inhibition, extinction or counterconditioning. Under these conditions, the retrieval of individual associations between a stimulus and outcome is affected by contextual cues. To examine the roles of the dorsal (prelimbic) and ventral (infralimbic) medial prefrontal cortex in the contextual modulation of such associations, we investigated the context specificity of latent inhibition. Male Lister hooded rats were pre-exposed to two separate stimuli, one in each of two distinct contexts. Both stimuli were then paired with the delivery of mild foot-shock in the same one of these contexts. Finally, the strength of the resultant conditioned emotional response (CER) to each stimulus was assessed in each context. For the sham-operated control rats, the CER was attenuated for each stimulus when it was tested in the context in which it had been pre-exposed. Rats who had received lesions to the infralimbic cortex showed this effect only in the conditioning context, whereas rats with lesions to the prelimbic cortex showed the effect only in the context in which conditioning had not taken place. These findings indicate that infralimbic and prelimbic cortices play distinct, and competing, roles in the contextual modulation of initial and later learning