Serial visual reversal learning in captive black-handed spider monkeys, Ateles geoffroyi.

Recent research suggests that socio-ecological factors such as dietary specialization and social complexity may be drivers of advanced cognitive skills among primates. Therefore, we assessed the ability of 12 black-handed spider monkeys (Ateles geoffroyi), a highly frugivorous platyrrhine primate with strong fission-fusion dynamics, to succeed in a serial visual reversal learning task. Using a two-alternative choice paradigm we first trained the animals to reliably choose a rewarded visual stimulus over a non-rewarded one. Upon reaching a pre-set learning criterion we then switched the reward values of the two stimuli and assessed if and how quickly the animals learned to reverse their choices, again to a pre-set learning criterion. This stimulus reversal procedure was then continued for a total of 80 sessions of 10 trials each. We found that the spider monkeys quickly learned to reliably discriminate between two simultaneously presented visual stimuli, that they succeeded in a visual reversal learning task, and that they displayed an increase in learning speed across consecutive reversals, suggesting that they are capable of serial reversal learning-set formation with visual cues. The fastest-learning individual completed five reversals within the 80 sessions. The spider monkeys outperformed most other primate and nonprimate mammal species tested so far on this type of cognitive task, including chimpanzees, with regard to their learning speed in both the initial learning task and in the first reversal task, suggesting a high degree of behavioral flexibility and inhibitory control. Our findings support the notion that socio-ecological factors such as dietary specialization and social complexity foster advanced cognitive skills in primates.

Implicit and Explicit Sequence Learning in Adults With Developmental Language Disorder.

PURPOSE: Developmental language disorder (DLD) is a neurodevelopmental disorder that impacts approximately 7% of the population and is characterized by unexplained deficits in expressive and/or receptive components of language. A common procedural learning task, serial reaction time (SRT), has been used to develop models of the basis of DLD. However, paradigms involve differing levels of implicit and explicit learning during this task, muddying interpretations of the data. Here, we tested adults with DLD on implicit and explicit SRT tasks to better understand implicit and explicit procedural learning in this population. We hypothesized that adults with DLD would demonstrate reduced learning on only the implicit SRT task, as alternate explicit neural mechanisms could lead to equivalent performance on the explicit task. METHOD: Fifty participants (25 with DLD and 25 with typical language) completed implicit and explicit SRT tasks, measuring their ability to learn visually presented 10-element sequences. Group differences were evaluated on sequence learning, error rates, and explicit recall of the sequence after learning. RESULTS: Sequence learning was the same between the groups on both tasks. However, individuals with DLD showed increased errors and significantly worse recall of the explicitly learned sequence. CONCLUSIONS: Results suggest that sequence learning may be intact in this population, while aspects of explicit learning and motoric responses are impaired. Results are interpreted in light of a neurobiological model of DLD. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.26210651.

Top-down and bottom-up oscillatory dynamics regulate implicit visuomotor sequence learning.

Implicit visuomotor sequence learning is crucial for acquiring skills that result in automated behaviors. The oscillatory dynamics underpinning this learning process are not well understood. To address this gap, the current study employed electroencephalography with a medium-density array (64 electrodes) to investigate oscillatory activity associated with implicit visuomotor sequence learning in the Serial Reaction Time task. In the task, participants unknowingly learn a series of finger movements. Eighty-five healthy adults participated in the study. Analyses revealed that theta activity at the vertex and alpha/beta activity over the motor areas decreased over the course of learning. No associations between alpha/beta and theta power were observed. These findings are interpreted within a dual-process framework: midline theta activity is posited to regulate top-down attentional processes, whereas beta activity from motor areas underlies the bottom-up encoding of sensory information from movement. From this model, we suggest that during implicit visuomotor sequence learning, top-down processes become disengaged (indicated by a reduction in theta activity), and modality specific bottom-up processes encode the motor sequence (indicated by a reduction in alpha/beta activity).

Can an isolated middle-series item make a "Dent" in the bow-shaped serial-position curve of comparative judgments?

Studies have shown that local (e.g., midseries) items' specific properties, including being isolated from rest of the items, can generate a local distinctiveness effect, enhancing the memory performance for the local items in serial recall or absolute judgments. However, this has not been the case in relative (comparative) judgments. For the first time, the present study found a local distinctiveness effect in comparative judgments by using an opposite-gender name for the midseries item in an otherwise uniformly one-gender name serial list. The reasons for the previous studies' failure to produce this effect in comparative judgments and the present study's success in obtaining it were discussed. The implication of the finding for the item/order information opponent-process theories was also suggested.

Implicit visuospatial sequence representations are accessible in both the practice and the transfer hand.

A serial reaction time task was used to test whether the representations of a probabilistic second-order sequence structure are (i) stored in an effector-dependent, effector-independent intrinsic or effector-independent visuospatial code and (ii) are inter-manually accessible. Participants were trained either with the dominant or non-dominant hand. Tests were performed with both hands in the practice sequence, a random sequence, and a mirror sequence. Learning did not differ significantly between left and right-hand practice, suggesting symmetric intermanual transfer from the dominant to the non-dominant hand and vice versa. In the posttest, RTs were shorter for the practice sequence than for the random sequence, and longest for the mirror sequence. Participants were unable to freely generate or recognize the practice sequence, indicating implicit knowledge of the probabilistic sequence structure. Because sequence-specific learning did not differ significantly between hands, we conclude that representations of the probabilistic sequence structure are stored in an effector-independent visuospatial code.

Grouping in working memory guides chunk formation in long-term memory: Evidence from the Hebb effect.

The Hebb effect refers to the improvement in immediate memory performance on a repeated list compared to unrepeated lists. That is, participants create a long-term memory representation over repetitions, on which they can draw in working memory tests. These long-term memory representations are likely formed by chunk acquisition: The whole list becomes integrated into a single unified representation. Previous research suggests that the formation of such chunks is rather inflexible and only occurs when at least the beginning of the list repeats across trials. However, recent work has shown that repetition learning strongly depends on participants recognizing the repeated information. Hence, successful chunk formation may depend on the recognizability of the repeated part of a list, and not on its position in the list. Across six experiments, we compared these two alternatives. We tested immediate serial recall of eight-letter lists, some of which partially repeated across trials. We used different partial-repetition structures, such as repeating only the first half of a list, or only every second item. We manipulated the salience of the repeating structure by spatially grouping and coloring the lists according to the repetition structure. We found that chunk formation is more flexible than previously assumed: Participants learned contiguous repeated sequences regardless of their position within the list, as long as they were able to recognize the repeated structure. Even when the repeated sequence occurred at varying positions over repetitions, learning was preserved when the repeated sequence was made salient by the spatial grouping. These findings suggest that chunk formation requires recognition of which items constitute a repeating group, and demonstrate a close link between grouping of information in working memory, and chunk formation in long-term memory.

Cardinal bias interacts with the stimulus history bias in orientation working memory.

Reports in a visual working memory(WM) task exhibit biases related to the categorical structure of the stimulus space (e.g., cardinal bias) as well as biases related to previously seen stumuli (e.g., serial bias). While these biases are common and can occur simultaneously, the extent to which they interact in WM remains unknown. In the present study, I used orientation delayed estimation tasks known to produce both cardinal and serial biases and found that the serial bias systematically varied based on the relative positions of the cardinal axis and the preceding stimulus in orientation space. When they were positioned in a way that generated cardinal and serial biases in the same direction (i.e., on the same side of the target orientation), reports for the target orientation exhibited a regular repulsive serial bias. However, when their positions resulted in the biases in the opposite directions (i.e., on the opposite side of the target orientation), no serial bias occurred. This absence of serial bias was replicated in a follow-up experiment where the locations of the stimulus orientation and the response probe were completely randomized, suggesting that the interaction occurs independently from location-based response preparation processes. Together, these results demonstrate that the prior stimulus and the cardinal axis impose interactive impact on the processing of new stimulus, producing differential patterns of serial bias depending on the specific stimulus being processed. These findings place significant implications on computational models addressing the nature of the stimulus history effect and its underlying mechanisms.

The Keys to the Future? An Examination of Statistical Versus Discriminative Accounts of Serial Pattern Learning.

Sequence learning is fundamental to a wide range of cognitive functions. Explaining how sequences-and the relations between the elements they comprise-are learned is a fundamental challenge to cognitive science. However, although hundreds of articles addressing this question are published each year, the actual learning mechanisms involved in the learning of sequences are rarely investigated. We present three experiments that seek to examine these mechanisms during a typing task. Experiments 1 and 2 tested learning during typing single letters on each trial. Experiment 3 tested for "chunking" of these letters into "words." The results of these experiments were used to examine the mechanisms that could best account for them, with a focus on two particular proposals: statistical transitional probability learning and discriminative error-driven learning. Experiments 1 and 2 showed that error-driven learning was a better predictor of response latencies than either n-gram frequencies or transitional probabilities. No evidence for chunking was found in Experiment 3, probably due to interspersing visual cues with the motor response. In addition, learning occurred across a greater distance in Experiment 1 than Experiment 2, suggesting that the greater predictability that comes with increased structure leads to greater learnability. These results shed new light on the mechanism responsible for sequence learning. Despite the widely held assumption that transitional probability learning is essential to this process, the present results suggest instead that the sequences are learned through a process of discriminative learning, involving prediction and feedback from prediction error.

Development of a novel rodent rapid serial visual presentation task reveals dissociable effects of stimulant versus nonstimulant treatments on attentional processes.

The rapid serial visual presentation (RSVP) task and continuous performance tasks (CPT) are used to assess attentional impairments in patients with psychiatric and neurological conditions. This study developed a novel touchscreen task for rats based on the structure of a human RSVP task and used pharmacological manipulations to investigate their effects on different performance measures. Normal animals were trained to respond to a target image and withhold responding to distractor images presented within a continuous sequence. In a second version of the task, a false-alarm image was included, so performance could be assessed relative to two types of nontarget distractors. The effects of acute administration of stimulant and nonstimulant treatments for ADHD (amphetamine and atomoxetine) were tested in both tasks. Methylphenidate, ketamine, and nicotine were tested in the first task only. Amphetamine made animals more impulsive and decreased overall accuracy but increased accuracy when the target was presented early in the image sequence. Atomoxetine improved accuracy overall with a specific reduction in false-alarm responses and a shift in the attentional curve reflecting improved accuracy for targets later in the image sequence. However, atomoxetine also slowed responding and increased omissions. Ketamine, nicotine, and methylphenidate had no specific effects at the doses tested. These results suggest that stimulant versus nonstimulant treatments have different effects on attention and impulsive behaviour in this rat version of an RSVP task. These results also suggest that RSVP-like tasks have the potential to be used to study attention in rodents.

Testing expectations and retrieval practice modulate repetition learning of visuospatial arrays.

One of the best-known demonstrations of long-term learning through repetition is the Hebb effect: Immediate recall of a memory list repeated amidst nonrepeated lists improves steadily with repetitions. However, previous studies often failed to observe this effect for visuospatial arrays. Souza and Oberauer (2022) showed that the strongest determinant for producing learning was the difficulty of the test: Learning was consistently observed when participants recalled all items of a visuospatial array (difficult test) but not if only one item was recalled, or recognition procedures were used (less difficult tests). This suggests that long-term learning was promoted by increased testing demands over the short term. Alternatively, it is possible that lower testing demands still lead to learning but prevented the application of what was learned. In four preregistered experiments (N = 981), we ruled out this alternative explanation: Changing the type of memory test midway through the experiment from less demanding (i.e., single item recall or recognition) to a more demanding test (i.e., full item recall) did not reveal hidden learning, and changing it from the more demanding to a less demanding test did not conceal learning. Mixing high and low demanding tests for nonrepeated arrays, however, eventually produced Hebb learning even for the less demanding testing conditions. We propose that testing affects long-term learning in two ways: Expectations of the test difficulty influence how information is encoded into memory, and retrieval consolidates this information in memory. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Hebb repetition effects in complex and simple span tasks are based on the same learning mechanism.

The Hebb repetition effect shows improvement in serial recall of repeated lists compared to random nonrepeated lists. Previous research using simple span tasks found that the Hebb repetition effect is limited to constant uninterrupted lists, suggesting chunking as the mechanism of list learning. However, the Hebb repetition effect has been found in complex span tasks, which challenges the chunking explanation, as successive list items are separated by distractor processing, possibly interfering with the unified representations. We tested the possibility that Hebb repetition learning arises from chunking in simple span, but from position-item associations in complex span. In a series of five experiments, we found evidence that contradicts that hypothesis. Results show that (a) Hebb repetition learning in a complex span task can be transferred to a simple span task; (b) Hebb repetition learning from a complex span task cannot be transferred to a partially repeated simple span task; (c) partial repetition in a complex span task does not lead to learning; (d) Hebb repetition learning from a simple span task can be transferred to a complex span task; and (e) repeating the distractors in complex span has no impact on the Hebb repetition effect. These results suggest that the mechanism underlying the Hebb repetition effect in simple and complex span tasks is the same and points at the creation of chunks while excluding the distractors from the long-term memory representation. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Serial reversal learning in an olfactory discrimination task in 3xTg-AD mice.

Male and female 3xTg-AD mice between 5 and 24 mo of age and their B6129F2/J wild-type controls were tested on a series of 18 olfactory discrimination and reversal tasks in an operant olfactometer. All mice learned the odor discriminations and reversals to a criterion of 85% correct, but the 3xTg-AD mice made fewer errors than the B6129F2/J mice in the odor discriminations and in the first six reversal learning tasks. Many mice showed evidence of near errorless learning, and on the reversal tasks the 3xTg-AD mice showed more instances of near errorless learning than the B6129F2/J mice. There was no evidence of an age effect on odor discrimination, but there was a decrease in errorless reversal learning in aged B6129F2/J mice. In long-term memory tests, there was an increase in the number of errors made but no genotype difference. The high level of performance indicates that the mice were able to develop a "learning to learn" strategy. The finding that the 3xTg-AD mice outperformed their littermate controls provides an example of paradoxical functional facilitation in these mice.

Nomen est omen: Serial reaction time task is not a motor but a visuomotor learning task.

The serial reaction time task is a widely used task in behavioural and cognitive neuroscience to assess human and animal learning. Many publications refer to this task as a 'motor learning task', but it is also a perceptual learning task. We emphasize here that the incorrect use of the term 'motor learning' misleads researchers and medical doctors by emphasizing the motor cortex's exclusive role. It has the potential to lead to the misinterpretation of neuroscientific, neuroimaging and clinical studies. The domino effect has the potential to generate more flawed hypotheses and theories.

Exploring the necessary conditions for phonological interference in serial recall.

This paper explores the impact of phonological overlap amongst items on short term memory recall performance by manipulating the type, number and syllabic position of shared phonemes between words in a serial recall task. Roodenrys et al [Roodenrys, S., Miller., L. M., & Josifoski, N. (2022b). Phonemic interference in short-term memory contributes to forgetting but it is not due to overwriting. Journal of Memory and Language, 122, 104301. https://doi.org/10.1016/j.jml.2021.104301] demonstrated that when the phonemes of a target word also occur in words earlier in the list, recall of the target word is impaired. Two experiments are reported that further examine the nature of this interference effect. Experiment 1 varied the type and number of phonemes shared with the single syllable target word by other list words and found a single shared vowel impaired target word recall performance as much as two shared consonants. Experiment 2 altered the syllabic position of the overlapping phonemes and found shared syllabic position was necessary to impair recall of the target word. It is argued these results show that not all phonological overlap is equally detrimental and specific psycholinguistic conditions are necessary to produce interference that impairs recall performance.

Repetition learning is neither a continuous nor an implicit process.

Learning advances through repetition. A classic paradigm for studying this process is the Hebb repetition effect: Immediate serial recall performance improves for lists presented repeatedly as compared to nonrepeated lists. Learning in the Hebb paradigm has been described as a slow but continuous accumulation of long-term memory traces over repetitions [e.g., Page & Norris, Phil. Trans. R. Soc. B 364, 3737-3753 (2009)]. Furthermore, it has been argued that Hebb repetition learning requires no awareness of the repetition, thereby being an instance of implicit learning [e.g., Guérard et al., Mem. Cogn. 39, 1012-1022 (2011); McKelvie,  J. Gen. Psychol. 114, 75-88 (1987)]. While these assumptions match the data from a group-level perspective, another picture emerges when analyzing data on the individual level. We used a Bayesian hierarchical mixture modeling approach to describe individual learning curves. In two preregistered experiments, using a visual and a verbal Hebb repetition task, we demonstrate that 1) individual learning curves show an abrupt onset followed by rapid growth, with a variable time for the onset of learning across individuals, and that 2) learning onset was preceded by, or coincided with, participants becoming aware of the repetition. These results imply that repetition learning is not implicit and that the appearance of a slow and gradual accumulation of knowledge is an artifact of averaging over individual learning curves.

Serial order depends on item-dependent and item-independent contexts.

We address four issues in response to Osth and Hurlstone's (2022) commentary on the context retrieval and updating (CRU) theory of serial order (Logan, 2021). First, we clarify the relations between CRU, chains, and associations. We show that CRU is not equivalent to a chaining theory and uses similarity rather than association to retrieve contexts. Second, we fix an error Logan (2021) made in accounting for the tendency to recall ACB instead of ACD in recalling ABCDEF (fill-in vs. in-fill errors, respectively). When implemented correctly, the idea that subjects mix the current context with an initial list cue after the first order error correctly predicts that fill-in errors are more frequent than in-fill errors. Third, we address position-specific prior-list intrusions, suggesting modifications to CRU and introducing a position-coding model based on CRU representations to account for them. We suggest that position-specific prior-list intrusions are evidence for position coding on some proportion of the trials but are not evidence against item coding on other trials. Finally, we address position-specific between-group intrusions in structured lists, agreeing with Osth and Hurlstone that reasonable modifications to CRU cannot account for them. We suggest that such intrusions support position coding on some proportion of the trials but do not rule out CRU-like item-based codes. We conclude by suggesting that item-independent and item-dependent coding are alternative strategies for serial recall and we stress the importance of accounting for immediate performance. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Gender differences in the serial position among older adults.

INTRODUCTION: There are gender disparities in age of diagnosis with Mild Cognitive Impairment (MCI) or dementia, which may be related to general female advantages in verbal memory across aging. Further examination of the serial position effect (SPE) may provide an avenue for earlier diagnosis of MCI/dementia among women. METHOD: 338 cognitively healthy adults aged 50+ (110 men; 228 women) were administered the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) List Learning task as part of dementia screening. We examined whether the SPE could be demonstrated on Trial 1 and delayed recall, and whether SPE patterns were consistent across genders, using mixed measure ANOVAs. Using regression, we also examined whether gender, SPE components, or their interactions predicted RBANS Delayed Memory Index (DMI) performance. Using cluster analyses, we identified a group with reduced primacy relative to recency on Trial 1 and a group without. We used ANOVA to examine whether clusters differed in DMI scores and whether this was moderated by gender. RESULTS: We demonstrated the prototypical SPE on Trial 1. On delayed recall, we found reduced recency compared to primacy and middle performance. As expected, men exhibited worse performance on the DMI. However, gender did not interact with SPE. Primacy and middle, but not recency, performance on Trial 1 predicted DMI scores, as did the recency ratio. These relationships were not moderated by gender. Finally, participants with better primacy than recency on Trial 1 (N = 187) exhibited higher performance on DMI than participants with better recency than primacy (N = 151). Gender did not interact with cluster membership. CONCLUSION: Our results have important clinical implications in assessment, where focusing on Trial 1 primacy performance and loss of recency between Trial 1 and delayed recall may help to address gender-related delays in age of diagnosis of MCI or dementia.

The effect of response-to-stimulus interval on children's implicit sequence learning.

The current study examined, for the first time in a developmental perspective, the effect of response-to-stimulus interval (RSI) in incidental sequence learning (SL). Children aged 4, 7, and 10 years performed a serial reaction time (SRT) task in which the RSI was systematically manipulated (0, 250, 500, or 750 ms). SL (difference in reaction times between fixed and random blocks) was not observed for the youngest children whatever the RSI condition, whereas the 7-year-olds learned the sequence only in the 250-ms RSI condition and the 10-year-olds exhibited SL in all temporal conditions except the 500-ms RSI condition. Finally, the results suggest that conscious awareness of the sequence emerges only in older children faced with the 500- and 750-ms RSI conditions. The discussion questions the robustness of implicit learning processes in the light of individual and contextual factors.

The impact of free will beliefs on implicit learning.

A growing number of studies demonstrate that belief in free will (FWB) is dynamic, and can be reduced experimentally. Most of these studies assume that doing so has beneficial effects on behavior, as FWBs are thought to subdue unwanted automatic processes (e.g. racial stereotypes). However, relying on automatic processes can sometimes be advantageous, for instance during implicit learning (e.g. detecting and exploiting statistical regularities in the environment). In this registered report, we tested whether experimentally reducing FWBs positively affected implicit motor learning. We hypothesized that reducing FWBs would lead to both faster and stronger implicit learning, as measured using the alternating serial reaction time (ASRT) task. While we did show a manipulation effect on free will beliefs, there was no detectable effect on implicit learning processes. This finding adds to the growing body of evidence that free will belief manipulations do not meaningfully affect downstream behavior.

Task-irrelevant auditory metre shapes visuomotor sequential learning.

The ability to learn and reproduce sequences is fundamental to every-day life, and deficits in sequential learning are associated with developmental disorders such as specific language impairment. Individual differences in sequential learning are usually investigated using the serial reaction time task (SRTT), wherein a participant responds to a series of regularly timed, seemingly random visual cues that in fact follow a repeating deterministic structure. Although manipulating inter-cue interval timing has been shown to adversely affect sequential learning, the role of metre (the patterning of salience across time) remains unexplored within the regularly timed, visual SRTT. The current experiment consists of an SRTT adapted to include task-irrelevant auditory rhythms conferring a sense of metre. We predicted that (1) participants' (n = 41) reaction times would reflect the auditory metric structure; (2) that disrupting the correspondence between the learned visual sequence and auditory metre would impede performance; and (3) that individual differences in sensitivity to rhythm would predict the magnitude of these effects. Altering the relationship via a phase shift between the trained visual sequence and auditory metre slowed reaction times. Sensitivity to rhythm was predictive of reaction times over all. In an exploratory analysis, we, moreover, found that approximately half of participants made systematically different responses to visual cues on the basis of the cues' position within the auditory metre. We demonstrate the influence of auditory temporal structures on visuomotor sequential learning in a widely used task where metre and timing are rarely considered. The current results indicate sensitivity to metre as a possible latent factor underpinning individual differences in SRTT performance.