Probabilistic Learning Task Research Articles

Behavioral Interventions Can Improve Brain Injury-Induced Deficits in Behavioral Flexibility and Impulsivity Linked to Impaired Reward-Feedback Beta Oscillations.

Traumatic brain injury (TBI) affects a large population, resulting in severe cognitive impairments. Although cognitive rehabilitation is an accepted treatment for some deficits, studies in patients are limited in ability to probe physiological and behavioral mechanisms. Therefore, animal models are needed to optimize strategies. Frontal TBI in a rat model results in robust and replicable cognitive deficits, making this an ideal candidate for investigating various behavioral interventions. In this study, we report three distinct frontal TBI experiments assessing behavior well into the chronic post-injury period using male Long-Evans rats. First, we evaluated the impact of frontal injury on local field potentials recorded simultaneously from 12 brain regions during a probabilistic reversal learning (PbR) task. Next, a set of rats were tested on a similar PbR task or an impulsivity task (differential reinforcement of low-rate behavior [DRL]) and half received salient cues associated with reinforcement contingencies to encourage engagement in the target behavior. After intervention on the PbR task, brains were stained for markers of activity. On the DRL task, cue relevance was decoupled from outcomes to determine if beneficial effects persisted on impulsive behavior. TBI decreased the ability to detect reinforced outcomes; this was evident in task performance and reward-feedback signals occurring at beta frequencies in lateral orbitofrontal cortex (OFC) and associated frontostriatal regions. The behavioral intervention improved flexibility and increased OFC activity. Intervention also reduced impulsivity, even after cues were decoupled, which was partially mediated by improvements in timing behavior. The current study established a platform to begin investigating cognitive rehabilitation in rats and identified a strong role for dysfunctional OFC signaling in probabilistic learning after frontal TBI.

Enhanced cognitive flexibility and phasic striatal dopamine dynamics in a mouse model of low striatal tonic dopamine.

The catecholamine neuromodulators dopamine and norepinephrine are implicated in motor function, motivation, and cognition. Although roles for striatal dopamine in these aspects of behavior are well established, the specific roles for cortical catecholamines in regulating striatal dopamine dynamics and behavior are less clear. We recently showed that elevating cortical dopamine but not norepinephrine suppresses hyperactivity in dopamine transporter knockout (DAT-KO) mice, which have elevated striatal dopamine levels. In contrast, norepinephrine transporter knockout (NET-KO) mice have a phenotype distinct from DAT-KO mice, as they show elevated extracellular cortical catecholamines but reduced baseline striatal dopamine levels. Here we evaluated the consequences of altered catecholamine levels in NET-KO mice on cognitive flexibility and striatal dopamine dynamics. In a probabilistic reversal learning task, NET-KO mice showed enhanced reversal learning, which was consistent with larger phasic dopamine transients (dLight) in the dorsomedial striatum (DMS) during reward delivery and reward omission, compared to WT controls. Selective depletion of dorsal medial prefrontal cortex (mPFC) norepinephrine in WT mice did not alter performance on the reversal learning task but reduced nestlet shredding. Surprisingly, NET-KO mice did not show altered breakpoints in a progressive ratio task, suggesting intact food motivation. Collectively, these studies show novel roles of cortical catecholamines in the regulation of tonic and phasic striatal dopamine dynamics and cognitive flexibility, updating our current views on dopamine regulation and informing future therapeutic strategies to counter multiple psychiatric disorders.

Non-motor symptoms associated with progressive loss of dopaminergic neurons in a mouse model of Parkinson's disease.

Parkinson's disease (PD) is characterized by three main motor symptoms: bradykinesia, rigidity and tremor. PD is also associated with diverse non-motor symptoms that may develop in parallel or precede motor dysfunctions, ranging from autonomic system dysfunctions and impaired sensory perception to cognitive deficits and depression. Here, we examine the role of the progressive loss of dopaminergic transmission in behaviors related to the non-motor symptoms of PD in a mouse model of the disease (the TIF-IADATCreERT2 strain). We found that in the period from 5 to 12 weeks after the induction of a gradual loss of dopaminergic neurons, mild motor symptoms became detectable, including changes in the distance between paws while standing as well as the swing speed and step sequence. Male mutant mice showed no apparent changes in olfactory acuity, no anhedonia-like behaviors, and normal learning in an instrumental task; however, a pronounced increase in the number of operant responses performed was noted. Similarly, female mice with progressive dopaminergic neuron degeneration showed normal learning in the probabilistic reversal learning task and no loss of sweet-taste preference, but again, a robustly higher number of choices were performed in the task. In both males and females, the higher number of instrumental responses did not affect the accuracy or the fraction of rewarded responses. Taken together, these data reveal discrete, dopamine-dependent non-motor symptoms that emerge in the early stages of dopaminergic neuron degeneration.

Characterisation of behaviours relevant to apathy syndrome in the aged male rat

Apathy is a complex psychiatric syndrome characterised by motivational deficit, emotional blunting and cognitive changes. It occurs alongside a broad range of neurological disorders, but also occurs in otherwise healthy ageing. Despite its clinical prevalence, apathy does not yet have a designated treatment strategy. Generation of a translational animal model of apathy syndrome would facilitate the development of novel treatments. Given the multidimensional nature of apathy, a model cannot be achieved with a single behavioural test. Using a battery of behavioural tests we investigated whether aged rats exhibit behavioural deficits across different domains relevant to apathy. Using the effort for reward and progressive ratio tasks we found that aged male rats (21–27 months) show intact reward motivation. Using the novelty supressed feeding test and position-based object exploration we found aged rats showed increased anxiety-like behaviour inconsistent with emotional blunting. The sucrose preference test and reward learning assay showed intact reward sensitivity and reward-related cognition in aged rats. However, using a bowl-digging version of the probabilistic reversal learning task, we found a deficit in cognitive flexibility in aged rats that did not translate across to a touchscreen version of the task. While these data reveal important changes in cognitive flexibility and anxiety associated with ageing, aged rats do not show deficits across other behavioural domains relevant to apathy. This suggests that aged rats are not a suitable model for age-related apathy syndrome. These findings contrast with previous work in mice, revealing important species differences in behaviours relevant to apathy syndrome in ageing.

Dysfunctional feedback processing in male methamphetamine abusers: Evidence from neurophysiological and computational approaches

Methamphetamine use disorder (MUD) as a major public health risk is associated with dysfunctional neural feedback processing. Although dysfunctional feedback processing in people who are substance dependent has been explored in several behavioral, computational, and electrocortical studies, this mechanism in MUDs requires to be well understood. Furthermore, the current understanding of latent components of their behavior such as learning speed and exploration-exploitation dilemma is still limited. In addition, the association between the latent cognitive components and the related neural mechanisms also needs to be explored. Therefore, in this study, the underlying neurocognitive mechanisms of feedback processing of such impairment, and age/gender-matched healthy controls are evaluated within a probabilistic learning task with rewards and punishments. Mathematical modeling results based on the Q-learning paradigm suggested that MUDs show less sensitivity in distinguishing optimal options. Additionally, it may be worth noting that MUDs exhibited a slight decrease in their ability to learn from negative feedback compared to healthy controls. Also through the lens of underlying neural mechanisms, MUDs showed lower theta power at the medial-frontal areas while responding to negative feedback. However, other EEG measures of reinforcement learning including feedback-related negativity, parietal-P300, and activity flow from the medial frontal to lateral prefrontal regions, remained intact in MUDs. On the other hand, the elimination of the linkage between value sensitivity and medial-frontal theta activity in MUDs was observed. The observed dysfunction could be due to the adverse effects of methamphetamine on the cortico-striatal dopamine circuit, which is reflected in the anterior cingulate cortex activity as the most likely region responsible for efficient behavior adjustment. These findings could help us to pave the way toward tailored therapeutic approaches.

Lasting dynamic effects of the psychedelic 2,5-dimethoxy-4-iodoamphetamine ((±)-DOI) on cognitive flexibility.

Psychedelic drugs can aid fast and lasting remission from various neuropsychiatric disorders, though the underlying mechanisms remain unclear. Preclinical studies suggest serotonergic psychedelics enhance neuronal plasticity, but whether neuroplastic changes can also be seen at cognitive and behavioural levels is unexplored. Here we show that a single dose of the psychedelic 2,5-dimethoxy-4-iodoamphetamine ((±)-DOI) affects structural brain plasticity and cognitive flexibility in young adult mice beyond the acute drug experience. Using ex vivo magnetic resonance imaging, we show increased volumes of several sensory and association areas one day after systemic administration of 2 mgkg-1 (±)-DOI. We then demonstrate lasting effects of (±)-DOI on cognitive flexibility in a two-step probabilistic reversal learning task where 2 mgkg-1 (±)-DOI improved the rate of adaptation to a novel reversal in task structure occurring one-week post-treatment. Strikingly, (±)-DOI-treated mice started learning from reward omissions, a unique strategy not typically seen in mice in this task, suggesting heightened sensitivity to previously overlooked cues. Crucially, further experiments revealed that (±)-DOI's effects on cognitive flexibility were contingent on the timing between drug treatment and the novel reversal, as well as on the nature of the intervening experience. (±)-DOI's facilitation of both cognitive adaptation and novel thinking strategies may contribute to the clinical benefits of psychedelic-assisted therapy, particularly in cases of perseverative behaviours and a resistance to change seen in depression, anxiety, or addiction. Furthermore, our findings highlight the crucial role of time-dependent neuroplasticity and the influence of experiential factors in shaping the therapeutic potential of psychedelic interventions for impaired cognitive flexibility.

Dynamics Learning Rate Bias in Pigeons: Insights from Reinforcement Learning and Neural Correlates

Research in reinforcement learning indicates that animals respond differently to positive and negative reward prediction errors, which can be calculated by assuming learning rate bias. Many studies have shown that humans and other animals have learning rate bias during learning, but it is unclear whether and how the bias changes throughout the entire learning process. Here, we recorded the behavior data and the local field potentials (LFPs) in the striatum of five pigeons performing a probabilistic learning task. Reinforcement learning models with and without learning rate biases were used to dynamically fit the pigeons’ choice behavior and estimate the option values. Furthemore, the correlation between the striatal LFPs power and the model-estimated option values was explored. We found that the pigeons’ learning rate bias shifted from negative to positive during the learning process, and the striatal Gamma (31 to 80 Hz) power correlated with the option values modulated by dynamic learning rate bias. In conclusion, our results support the hypothesis that pigeons employ a dynamic learning strategy in the learning process from both behavioral and neural aspects, providing valuable insights into reinforcement learning mechanisms of non-human animals.

Prospective associations between cognitive flexibility and eating disorder symptoms in anorexia nervosa and bulimia nervosa

This study investigated concurrent and prospective associations between measures of reversal learning and attentional set-shifting and eating disorder symptoms at baseline, 3 months, and 6 months among individuals with anorexia nervosa restricting subtype (AN-R, n = 26), AN binge eating/purging subtype (AN-BP, n = 22), bulimia nervosa (BN, n = 35), and healthy controls (n = 27), and explored whether these associations differed by diagnosis. At baseline, participants completed diagnostic interviews, height/weight measurements, and measures of set-shifting (the Intradimensional/Extradimensional shift task) and reversal learning (a probabilistic reversal learning task). At 3- and 6-month follow-up, participants with eating disorders completed assessments of weight and eating disorder symptoms. A one-way analysis of variance found no evidence that baseline reversal learning and attentional set-shifting differed across diagnostic groups. Multilevel modeling analyses indicated that perseverative errors (an index of reversal learning) predicted an increase in purging over time for individuals with AN-BP and BN. Set-shifting errors differentially predicted frequency of loss of control eating for individuals with AN-BP and BN; however, set-shifting was not related to loss of control eating when examined separately in AN-BP and BN. These findings suggest that disentangling facets of cognitive flexibility may help understand change in eating disorder symptoms.

Reduced brain connectivity underlying value-based choices and outcomes in stimulant use disorder

BACKGROUND: Patients with stimulant use disorder (SUD) show impairments when making value-based choices that are associated with disruptions in neural processing across brain networks. Making optimal choices requires learning from outcomes to update knowledge and further optimise ongoing behaviour. The optimal functioning of neural systems that underpin the ability to make favourable choices is an essential component for life functioning, and successful recovery in patients with SUD. Therefore, we sought to investigate the neural processes that underpin value-based choices in SUD patients. We hypothesise that patients with SUD have reduced functional connectivity while making financial choices during a probabilistic reinforcement learning task. METHODS: We investigated connectivity associated with loss and reward value-based choices and their outcomes in patients with SUD and healthy control participants during a pharmacological magnetic resonance imaging study. Participants received a single dose of a dopamine receptor agonist, pramipexole, and a dopamine receptor antagonist, amisulpride, in a randomised, double-blind, placebo-controlled, balanced, crossover design. Functional task-related connectivity was analysed taking a whole brain connectomics approach to identify networks that are differentially modulated by dopaminergic receptor functioning. RESULTS: SUD patients showed widespread reductions in connectivity during both reward and loss value-based choices and outcomes, which were negatively correlated with the duration of stimulant drug use. Disturbances to functional brain connectivity in SUD patients during task performance were not modulated acutely by either amisulpride or pramipexole. CONCLUSIONS: Reductions in brain connectivity, particularly when making value-based choices and processing outcomes, may underlie learning impairments in SUD patients. Given that acute dopaminergic modulation did not improve brain connectivity impairments in SUD patients, it is likely that alternative treatments are needed.

Ketamine produces no detectable long-term positive or negative effects on cognitive flexibility or reinforcement learning of male rats.

Patients with major depressive disorder (MDD) often experience abnormalities in behavioral adaptation following environmental changes (i.e., cognitive flexibility) and tend to undervalue positive outcomes but overvalue negative outcomes. The probabilistic reversal learning task (PRL) is used to study these deficits across species and to explore drugs that may have therapeutic value. Selective serotonin-reuptake inhibitors (SSRIs) have limited effectiveness in treating MDD and produce inconsistent effects in non-human versions of the PRL. As such, ketamine, a novel and potentially rapid-acting therapeutic, has begun to be examined using the PRL. Two previous studies examining the effects of ketamine in the PRL have shown conflicting results and only examined short-term effects of ketamine. This experiment examined PRL performance across a 2-week period following a single exposure to a ketamine dose that varied across groups. After five sessions of PRL training, groups of rats received an injection of either 0, 10, 20 or 30 mg/kg ketamine. One-hour post-injection, rats engaged in the PRL, and subsequently sessions continued daily for 2 weeks. Traditional behavioral and computational reinforcement learning-derived measures were examined. Results showed that ketamine had acute effects 1-h post-injection, including a significant decrease in the value of the punishment learning rate. Beyond 1 h, ketamine produced no detectable improvements nor decrements in performance across 2 weeks. Overall, the present results suggest that the range of ketamine doses examined do not have long-term positive or negative effects on cognitive flexibility or reward processing in healthy rats as measured by the PRL.

Graph theoretical analysis demonstrates associations among cortical network segregation, β‐amyloid status, and reward‐based learning in older age

AbstractBackgroundAs humans age, brain networks supporting cognition show alterations in functional connectivity patterns consistent with network dedifferentiation. Here we examined the extent to which Alzheimer’s disease (AD)‐related β‐amyloid (Aβ) pathology exacerbates functional dedifferentiation in aging and is associated with reduced probabilistic reward‐based learning.Method27 young and 47 cognitively normal older adults underwent 3T functional magnetic resonance imaging (MRI) while performing a novel probabilistic learning task. The task required participants to learn the identity of real‐estate agents as “winning,” “losing,” or “break‐even” based on their success in selling houses for a profit. We used graph theoretical analysis and applied 400 regions of interest to identify age‐related changes in functional brain networks during early and late learning phases in the task. Older adults were characterized as Aβ‐ (n = 34) or Aβ+ (n = 13) using [11C]Pittsburgh Compound‐B positron emission tomography. Analyses focused on the two graph theory measures commonly linked to dedifferentiation (i.e. loss of segregation): clustering coefficient and modularity.ResultsYoung adults showed better learning performance, followed by Aβ‐ older adults and then Aβ+ older adults, but there was no significant age difference between young and Aβ‐ older adults (Fig. 1). Young adults also showed a higher clustering coefficient, which indicates greater network segregation, followed by Aβ‐ older adults and then Aβ+ older adults (Fig. 2A and 2B). Considering the learning phase, we found differences between the young and both Aβ‐ and Aβ+ older adults in the early learning phase (Fig. 2A), and differences between young and only Aβ+ older adults in the late learning phase (Fig. 2B). Analyses of modularity showed similar patterns of results, though the main effect of group was not significant (Fig. 2C and 2D). There was an interaction between network segregation and group to predict learning performance. Only Aβ‐ older adults with higher network segregation exhibited better learning performance (Fig. 3).ConclusionThese findings indicate Aβ is associated with functional network dedifferentiation and poorer learning performance. For Aβ‐ older adults, successful maintenance of brain network segregation may underlie the preservation of “youth‐like” cognitive performance.

Compulsivity and Inhibitory Control Deficits in Abstinent Individuals With Heroin Addiction and Their Biological Siblings Compared With Unrelated Healthy Control Participants

BackgroundCompulsivity represents the performance of persistent and repetitive acts despite negative consequences and is considered one of the critical mechanisms for drug addiction. Although compulsivity-related neurocognitive impairments have been linked to addiction, it remains unclear whether these deficits might have predated drug abuse as potential familial susceptibilities. MethodsA large sample of 213 adult participants were recruited, including 70 abstinent individuals addicted to heroin (HAs), 69 unaffected biological siblings of the HAs (siblings), and 74 unrelated healthy control participants. Compulsivity-related neurocognitive functions were evaluated using the intradimensional/extradimensional set-shift task and a probabilistic reversal learning task. Compulsive traits were measured by the Obsessive-Compulsive Inventory-Revised. Inhibitory control was assessed using the stop signal task and Stroop Color and Word Test. Network models for group recognition were conducted using multilayer perceptron neural networks. ResultsData indicated that both HAs and siblings performed worse than healthy control participants on compulsivity-related aspects (i.e., shifting and reversal learning functions) and inhibitory control and had higher levels of self-reported compulsive traits. Furthermore, neural models revealed that a possible 3-facet clustering of neurocognitive deficits was linked to both HAs and siblings. ConclusionsOur findings suggest that deficits in shift reversal and inhibitory control aspects and elevated compulsive traits, shared by HAs and their unaffected siblings, may putatively represent conceivable markers associated with familial vulnerabilities implicated in the development of heroin dependence.

Meta-reinforcement learning via orbitofrontal cortex

The meta-reinforcement learning (meta-RL) framework, which involves RL over multiple timescales, has been successful in training deep RL models that generalize to new environments. It has been hypothesized that the prefrontal cortex may mediate meta-RL in the brain, but the evidence is scarce. Here we show that the orbitofrontal cortex (OFC) mediates meta-RL. We trained mice and deep RL models on a probabilistic reversal learning task across sessions during which they improved their trial-by-trial RL policy through meta-learning. Ca2+/calmodulin-dependent protein kinase II-dependent synaptic plasticity in OFC was necessary for this meta-learning but not for the within-session trial-by-trial RL in experts. After meta-learning, OFC activity robustly encoded value signals, and OFC inactivation impaired the RL behaviors. Longitudinal tracking of OFC activity revealed that meta-learning gradually shapes population value coding to guide the ongoing behavioral policy. Our results indicate that two distinct RL algorithms with distinct neural mechanisms and timescales coexist in OFC to support adaptive decision-making.

Anxiety associated with perceived uncontrollable stress enhances expectations of environmental volatility and impairs reward learning

Unavoidable stress can lead to perceived lack of control and learned helplessness, a risk factor for depression. Avoiding punishment and gaining rewards involve updating the values of actions based on experience. Such updating is however useful only if action values are sufficiently stable, something that a lack of control may impair. We examined whether self-reported stress uncontrollability during the first wave of the COVID-19 pandemic predicted impaired reward-learning. In a preregistered study during the first-wave of the COVID-19 pandemic, we used self-reported measures of depression, anxiety, uncontrollable stress, and COVID-19 risk from 427 online participants to predict performance in a three-armed-bandit probabilistic reward learning task. As hypothesised, uncontrollable stress predicted impaired learning, and a greater proportion of probabilistic errors following negative feedback for correct choices, an effect mediated by state anxiety. A parameter from the best-fitting hidden Markov model that estimates expected beliefs that the identity of the optimal choice will shift across images, mediated effects of state anxiety on probabilistic errors and learning deficits. Our findings show that following uncontrollable stress, anxiety promotes an overly volatile representation of the reward-structure of uncertain environments, impairing reward attainment, which is a potential path to anhedonia in depression.

Metabolic and functional substrates of impulsive decision-making in individuals with heroin addiction after prolonged methadone maintenance treatment

Elevated impulsivity has been frequently reported in individuals with opioid addiction receiving methadone maintenance therapy (MMT), but the underlying neural mechanisms and cognitive subprocesses are not fully understood. We acquired functional magnetic resonance imaging (fMRI) data from 37 subjects with heroin addiction receiving long-term MMT and 33 healthy controls who performed a probabilistic reversal learning task, and measured their resting-state brain glucose using fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET). Subjects receiving MMT exhibited significantly elevated self-reported impulsivity, and computational modeling revealed a marked impulsive decision bias manifested as switching more frequently without available evidence. Moreover, this impulsive decision bias was associated with the dose and duration of methadone use, irrelevant to the duration of heroin use. During the task, the switch-related hypoactivation in the left rostral middle frontal gyrus was correlated with the impulsive decision bias while the function of reward sensitivity was intact in subjects receiving MMT. Using prior brain-wide receptor density data, we found that the highest variance of regional metabolic abnormalities was explained by the spatial distribution of μ-opioid receptors among 10 types of neurotransmitter receptors. Heightened impulsivity in individuals receiving prolonged MMT is manifested as atypical choice bias and noise in decision-making processes, which is further driven by deficits in top-down cognitive control, other than reward sensitivity. Our findings uncover multifaceted mechanisms underlying elevated impulsivity in subjects receiving MMT, which might provide insights for developing complementary therapies to improve retention during MMT.

Impaired implicit learning in adults with anorexia nervosa.

Cognitive alterations play an important role in the pathophysiology and treatment of anorexia nervosa (AN). Previous studies suggest that some implicit learning processes may be inhibited in AN. However, this has not yet been fully explored. The purpose of this study is to analyze implicit learning in patients with AN in comparison to healthy controls. In this pilot-study, a total of 21 patients diagnosed with AN and 21 matched controls were administered the weather prediction task (WPT), a probabilistic implicit category learning task that consists of two sub-variants. During the feedback (FB) version of the task, participants learn associations between tarot cards and weather outcomes via an operant learning model through which they receive immediate FB on their answers, whereas during the paired associate (PA) variant, participants are directly asked to memorize given associations. AN patients showed selective impairment on the FB task where they scored significantly lower both in comparison to controls (p = .001) who completed the same task and when compared to their own performance on the PA variant (p = .006). Clinical measures showed no significant correlations with test scores. Our results demonstrate implicit FB learning deficiencies in adult patients with AN. These impairments may have an impact on the effect of psychotherapeutic interventions and could partially explain the lack of treatment response in AN. Further studies are necessary to derive when and through which mechanisms these alterations originate, and to what extent they should be considered during treatment of the disorder. Cognitive impairments pose a challenge in the management of anorexia nervosa. Improved comprehension of cognitive alterations could lead to a greater understanding of the disease and adaptation of psychotherapeutic treatments. In this study, we found that implicit feedback learning in anorexia nervosa is impaired compared to healthy controls. This could indicate the necessity of treatment adaptations in the form of therapy tools without feedback and a larger focus on psychoeducation.

Depth recordings of the mouse homologue of the Reward Positivity.

We recently advanced a rodent homologue for the reward-specific, event-related potential component observed in humans known as the Reward Positivity. We sought to determine the cortical source of this signal in mice to further test the nature of this homology. While similar reward-related cortical signals have been identified in rats, these recordings were all performed in cingulate gyrus. Given the value-dependent nature of this event, we hypothesized that more ventral prelimbic and infralimbic areas also contribute important variance to this signal. Depth probes assessed local field activity in 29 mice (15 males) while they completed multiple sessions of a probabilistic reinforcement learning task. Using a priori regions of interest, we demonstrated that the depth of recording in the cortical midline significantly correlated with the size of reward-evoked delta band spectral activity as well as the single trial correlation between delta power and reward prediction error. These findings provide important verification of the validity of this translational biomarker of reward responsiveness, learning, and valuation.

Further perceptions of probability: In defence of associative models.

Extensive research in the behavioral sciences has addressed people's ability to learn stationary probabilities, which stay constant over time, but only recently have there been attempts to model the cognitive processes whereby people learn-and track-nonstationary probabilities. In this context, the old debate on whether learning occurs by the gradual formation of associations or by occasional shifts between hypotheses representing beliefs about distal states of the world has resurfaced. Gallistel et al. (2014) pitched the two theories against each other in a nonstationary probability learning task. They concluded that various qualitative patterns in their data were incompatible with trial-by-trial associative learning and could only be explained by a hypothesis-testing model. Here, we contest that claim and demonstrate that it was premature. First, we argue that their experimental paradigm consisted of two distinct tasks: probability tracking (an estimation task) and change detection (a decision-making task). Next, we present a model that uses the (associative) delta learning rule for the probability tracking task and bounded evidence accumulation for the change detection task. We find that this combination of two highly established theories accounts well for all qualitative phenomena and outperforms the alternative model proposed by Gallistel et al. (2014) in a quantitative model comparison. In the spirit of cumulative science, we conclude that current experimental data on human learning of nonstationary probabilities can be explained as a combination of associative learning and bounded evidence accumulation and does not require a new model. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Stability of individual differences in implicitly guided attention.

Daily activities often occur in familiar environments, affording us an opportunity to learn. Laboratory studies have shown that people readily acquire an implicit spatial preference for locations that frequently contained a search target in the past. These studies, however, have focused on group characteristics, downplaying the significance of individual differences. In a pre-registered study, we examined the stability of individual differences in two variants of an implicit location probability learning (LPL) task. We tested the possibility that individual differences were stable in variants that shared the same search process, but not in variants involving different search processes. In Experiment 1, participants performed alternating blocks of T-among-Ls and 5-among-2s search tasks. Unbeknownst to them, the search target appeared disproportionately often in one region of space; the high-probability regions differed between the two tasks. LPL transferred between the two tasks. In addition, individuals who showed greater LPL in the T-task also did so in the 5-task and vice versa. In Experiment 2, participants searched for either a camouflaged-T against background noise or a well-segmented T among well-segmented Ls. These two tasks produced task-specific learning that did not transfer between tasks. Moreover, individual differences in learning did not correlate between tasks. Thus, LPL is associated with stable individual differences across variants, but only when the variants share common search processes.

With or without Feedback?-How the Presence of Feedback Affects Processing in Children with Developmental Language Disorder.

Language acquisition depends on the ability to process and learn probabilistic information, often through the integration of performance feedback. Children with developmental language disorder (DLD) have demonstrated weaknesses in both probabilistic learning and feedback processing, but the individual effects of each skill are poorly understood in this population. This study examined school-aged children with DLD (n = 29) and age- and gender-matched children with typical development (TD; n = 44) on a visual probabilistic classification learning task presented with and without feedback. In the feedback-based version of the task, children received performance feedback on a trial-by-trial basis during the training phase of the task. In the feedback-free version, children responded after seeing the correct choice marked with a green border and were not presented with feedback. Children with TD achieved higher accuracy than children with DLD following feedback-based training, while the two groups achieved similar levels of accuracy following feedback-free training. Analyses of event-related potentials (ERPs) provided insight into stimulus encoding processes. The feedback-free task was dominated by a frontal slow wave (FSW) and a late parietal component (LPC) which were not different between the two groups. The feedback-based task was dominated by a parietal slow wave (PSW) and an LPC, both of which were found to be larger in the TD than in the DLD group. In combination, results suggest that engagement with feedback boosts learning in children with TD, but not in children with DLD. When the need to process feedback is eliminated, children with DLD demonstrate behavioral and neurophysiological responses similar to their peers with TD.