Perception Of Sequences Research Articles

Implicit learning of perceptual sequences is preserved in Parkinson's disease.

Various studies investigated implicit sequence learning in Parkinson's disease (PD) by means of the traditional motor Serial Reaction Time (SRT) task and found a general pattern of impaired sequence learning. However, as perceptual and motor sequences of the SRT-task were correlated in previous studies, implicit sequential knowledge acquisition that is tested independently from motor sequences remains to be determined in PD. In this study, we investigated implicit sequence learning independently from motor sequence learning in individuals with PD. To this end, we used a perceptual SRT-task that did not rely upon sequential motor knowledge. We measured response times (RTs) of 19 participants with PD (Hoehn & Yahr II or III; mean age 65) and 18 age-matched healthy controls (HC; mean age 61.5) in a perceptual SRT-task. General learning effects and sequence-specific learning effects were analyzed using repeated measures ANOVAs. A significant decreasing linear trend (p < .001) in RTs was revealed in both the PD and HC groups as the SRT-task progressed, indicating general learning effects. Notably, a significant, strong main effect of sequence-specific learning occurred (p < .001), irrespective of group (p = .436). Sequence-specific learning did not differ significantly between the PD (M = 156.5 ms; SD = 50.7) and HC group (M = 173.0 ms; SD = 104.2). Bayesian analyses confirmed this as evidence of absence of an effect (B₁₀ = 3.543). Our results suggest that, at least in Hoehn & Yahr stages II and III, implicit sequential knowledge acquisition may be preserved in individuals with PD, when tested independently from motor sequence learning. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Adjustments of selective attention to response conflict \u2013 controlling for perceptual conflict, target-distractor identity, and congruency level sequence pertaining to the congruency sequence effect

The congruency sequence effect (CSE) describes the performance difference of congruent trials (in which target and distractor stimuli are associated with the same response) compared to incongruent trials (in which target and distractor stimuli are associated with different responses) as a function of the preceding congruency level (congruent trials relative to incongruent trials). The CSE is commonly interpreted as a measure of conflict-induced attentional adjustment. Although previous research has made substantial progress aiming at controlling for alternative explanations of the CSE, both task-specific and fundamental confounds have remained. In the current study, we used a temporal flanker task, in which two stimuli (i.e., distractor and target) are presented in rapid succession, and extended previous demonstrations of a CSE in flanker tasks by deconfounding target-distractor congruency from perceptual similarity. Using a four-choice task, we could also control for the reversal of distractor-response priming after incongruent trials (which is only feasible in two-choice tasks). Furthermore, we controlled for all confounds based on the sequence (i.e., repetition versus alternation) of the congruency level – such as feature sequence effects, distractor-response contingency switch costs, or temporal learning – by probing the allocation of attention to the points in time of presentation of the first and the second stimulus of a trial. This was achieved by intermixing trials of a temporal search task. The performance accuracy results in this task were consistent with a stronger attentional bias in favor of the target stimulus’ temporal position after incongruent than after congruent trials.

Are self-caused distractors easier to ignore? Experiments with the flanker task.

Four experiments are reported that investigate the relationship between action-outcome learning and the ability to ignore distractors. Each participant performed 600 acquisition trials, followed by 200 test trials. In the acquisition phase, participants were presented with a fixed action-outcome contingency (e.g., Key #1 ➔ green distractors), while that contingency was reversed in the test phase. In Experiments 1-3, a distractor feature depended on the participants' action. In Experiment 1, actions determined the color of the distractors; in Experiment 2, they determined the target-distractor distance; in Experiment 3, they determined target-distractor compatibility. Results suggest that with the relatively simple features (color and distance), exposure to action-outcome contingencies changed distractor cost, whereas with the complex or relational feature (target-distractor compatibility), exposure to the contingencies did not affect distractor cost. In Experiment 4, the same pattern of results was found (effect of contingency learning on distractor cost) with perceptual sequence learning, using visual cues ("X" vs. "O") instead of actions. Thus, although the mechanism of associative learning may not be unique to actions, such learning plays a role in the allocation of attention to task-irrelevant events.

Handwriting perceptual classification and synthesis using discriminate HMMs and progressive iterative approximation

This paper handles the problem of online handwriting synthesis. Indeed, this work presents a probabilistic model using the embedded hidden Markov models (HMMs) for the classification and modeling of perceptual sequences. At first, we start with a vector of perceptual points as input seeking a class of basic shape probability as output. In fact, these perceptual points are necessary for the drawing and the recovering of each basic shape where each one is designed with an HMM built and trained with its components. Each path through these possibilities of control points represents an observation that serves as input for the following step. Secondly, the already detected sequences of observations which represent a segment formed an initial HMM and the concatenation of multiple ones leads to a global HMM. To classify a global HMM, we should codify it by searching the best path of initial HMM. The best path is obtained by computing the maximum of likelihood of the different basic shapes. In order to synthesize the handwritten trace, and to recover the best control points sequences, we investigated the progressive iterative approximation. The performance of the proposed model was assessed using samples of scripts extracted from IRONOFF and MAYASTROON databases. In fact, these samples served for the generation of the set of control points used for the HMMs training models. In experiments, good quantitative agreement and approximation were found for the generated trajectories and a more reduced representation of the scripts models was designed.

Interaction Between Transcranial Random Noise Stimulation and Observation-Execution Matching Activity Promotes Motor Cortex Excitability.

Pathways of the human mirror neuron system are activated during both, action observation and action execution, including lateralized activation of respective areas, as shown by observed right-or left-hand actions. Here, we investigated whether execution-dependent motor cortex excitability is affected by prior interaction between transcranial random noise stimulation (tRNS) and action observation. Sham or real tRNS (1 mA) was applied for 10-min over the left primary motor cortex during action observation. In the main experiments, participants received sham or real tRNS while they watched a video showing repeated tapping tasks, involving either the right-hand (Experiment 1, congruent action observation), or a mirror-reversed video showing the same performance (Experiment 2), followed by action execution of the right-hand. In control Experiments 1–3, participants received real tRNS while observing a perceptual sequence, watching a landscape picture, or observing the left-hand performing the action (the sequence was identical to Experiment 1), followed by action execution of the right-hand. In control Experiment 4, participants received real tRNS during congruent action observation, and then took 6-min rest. Motor-evoked potentials (MEP) were recorded before action observation, a perceptual sequence or a landscape picture, immediately after, and after action execution, or an interval of 6-min, dependent on the respective experimental condition. MEPs in the right first dorsal interosseous muscle increased significantly after real tRNS combined with congruent action observation, and after action execution compared to the sham session in Experiment 1 and control experiments. We conclude that prior interaction between real tRNS and action observation of mirror-matched movements modulates subsequent execution-dependent motor cortex excitability.

Alpha-gamma phase amplitude coupling subserves information transfer during perceptual sequence learning.

Cross-frequency coupling is suggested to serve transfer of information between wide-spread neuronal assemblies and has been shown to underlie many cognitive functions including learning and memory. In previous work, we found that alpha (8-13 Hz) - gamma (30-48 Hz) phase amplitude coupling (αγPAC) is decreased during sequence learning in bilateral frontal cortex and right parietal cortex. We interpreted this to reflect decreased demands for visuo-motor mapping once the sequence has been encoded. In the present study, we put this hypothesis to the test by adding a "simple" condition to the standard serial reaction time task (SRTT) with minimal needs for visuo-motor mapping. The standard SRTT in our paradigm entailed a perceptual sequence allowing for implicit learning of a sequence of colors with randomly assigned motor responses. Sequence learning in this case was thus not associated with reduced demands for visuo-motor mapping. Analysis of oscillatory power revealed a learning-related alpha decrease pointing to a stronger recruitment of occipito-parietal areas when encoding the perceptual sequence. Replicating our previous findings but in contrast to our hypothesis, αγPAC was decreased in sequence compared to random trials over right frontal and parietal cortex. It also tended to be smaller compared to trials requiring a simple motor sequence. We additionally analyzed αγPAC in resting-state data of a separate cohort. PAC in electrodes over right parietal cortex was significantly stronger compared to sequence trials and tended to be higher compared to simple and random trials of the SRTT data. We suggest that αγPAC in right parietal cortex reflects a "default-mode" brain state, which gets perturbed to allow for encoding of visual regularities into memory.

Is sequence awareness mandatory for perceptual sequence learning: An assessment using a pure perceptual sequence learning design

We examined the role of sequence awareness in a pure perceptual sequence learning design. Participants had to react to the target's colour that changed according to a perceptual sequence. By varying the mapping of the target's colour onto the response keys, motor responses changed randomly. The effect of sequence awareness on perceptual sequence learning was determined by manipulating the learning instructions (explicit versus implicit) and assessing the amount of sequence awareness after the experiment. In the explicit instruction condition (n = 15), participants were instructed to intentionally search for the colour sequence, whereas in the implicit instruction condition (n = 15), they were left uninformed about the sequenced nature of the task. Sequence awareness after the sequence learning task was tested by means of a questionnaire and the process-dissociation-procedure. The results showed that the instruction manipulation had no effect on the amount of perceptual sequence learning. Based on their report to have actively applied their sequence knowledge during the experiment, participants were subsequently regrouped in a sequence strategy group (n = 14, of which 4 participants from the implicit instruction condition and 10 participants from the explicit instruction condition) and a no-sequence strategy group (n = 16, of which 11 participants from the implicit instruction condition and 5 participants from the explicit instruction condition). Only participants of the sequence strategy group showed reliable perceptual sequence learning and sequence awareness. These results indicate that perceptual sequence learning depends upon the continuous employment of strategic cognitive control processes on sequence knowledge. Sequence awareness is suggested to be a necessary but not sufficient condition for perceptual learning to take place.

An efficient speech perceptual hashing authentication algorithm based on DWT and symmetric ternary string

According to the situation that speech perceptual hashing methods are not appropriated for real-time speech content authentication in mobile computing environment, a novel DWT-based perceptual hashing algorithm, which uses a combination of time-domain and frequency-domain features, was proposed to protect the speech data in the cloud. Firstly, by discrete wavelet transform (DWT), a new signal in frequency-domain is generated from the original speech signal after pre-processing and intensity-loudness transform (ILT). Secondly, coefficients of low frequency wavelet decomposition are partitioned into equal-sized and non-overlapping blocks, and logarithmic short-time energy of each block is computed to obtain speech signals features in frequency-domain. Finally, combined with spectral flux features (SFF) of speech signal in time-domain, a ternary perceptual hashing sequence is created. Experiment results illustrate that ternary form is better to stand for hash digest than binary form, the proposed algorithm has a good robustness against content preserving operations, discrimination, good compaction and high efficiency, and detects the tamper localisation as well.

Perceptual and positional saliencies influence children's sequence learning differently with age and instructions at test.

There is growing evidence that, faced with a complex environment, participants subdivide the incoming information into small perceptual units, called chunks. Although statistical properties have been identified as playing a key role in chunking, we wanted to determine whether perceptual (repetitions) and positional (initial units) features might provide immediate guidance for the parsing of information into chunks. Children aged 5 and 8 years were exposed to sequences of 3, 4, or 5 colours. Sequence learning was assessed either through an explicit generation test (Experiment 1) or through a recognition test (Experiment 2). Experiment 1 showed that perceptual and positional saliencies benefited learning and that sensitivity to repetitions was age dependent and permitted the formation of longer chunks (trigrams) in the oldest children. Experiment 2 suggested that children became sensitive to perceptual and positional saliencies regardless of age and that the both types of saliencies supported the formation of longer chunks in the oldest children. The discussion focuses on the multiple factors intervening in sequence learning and their differential effects as a function of the instructions used at test to assess sequence learning.

Influence of Cognitive Functioning on Age-Related Performance Declines in Visuospatial Sequence Learning.

Objectives: The aim of this study was to investigate how age-related performance differences in a visuospatial sequence learning task relate to age-related declines in cognitive functioning.Method: Cognitive functioning of 18 younger and 18 older participants was assessed using a standardized test battery. Participants then undertook a perceptual visuospatial sequence learning task. Various relationships between sequence learning and participants’ cognitive functioning were examined through correlation and factor analysis.Results: Older participants exhibited significantly lower performance than their younger counterparts in the sequence learning task as well as in multiple cognitive functions. Factor analysis revealed two independent subsets of cognitive functions associated with performance in the sequence learning task, related to either the processing and storage of sequence information (first subset) or problem solving (second subset). Age-related declines were only found for the first subset of cognitive functions, which also explained a significant degree of the performance differences in the sequence learning task between age-groups.Discussion: The results suggest that age-related performance differences in perceptual visuospatial sequence learning can be explained by declines in the ability to process and store sequence information in older adults, while a set of cognitive functions related to problem solving mediates performance differences independent of age.

Abstract feature codes: The building blocks of the implicit learning system.

According to the Theory of Event Coding (TEC; Hommel, Müsseler, Aschersleben, & Prinz, 2001), action and perception are represented in a shared format in the cognitive system by means of feature codes. In implicit sequence learning research, it is still common to make a conceptual difference between independent motor and perceptual sequences. This supposedly independent learning takes place in encapsulated modules (Keele, Ivry, Mayr, Hazeltine, & Heuer 2003) that process information along single dimensions. These dimensions have remained underspecified so far. It is especially not clear whether stimulus and response characteristics are processed in separate modules. Here, we suggest that feature dimensions as they are described in the TEC should be viewed as the basic content of modules of implicit learning. This means that the modules process all stimulus and response information related to certain feature dimensions of the perceptual environment. In 3 experiments, we investigated by means of a serial reaction time task the nature of the basic units of implicit learning. As a test case, we used stimulus location sequence learning. The results show that a stimulus location sequence and a response location sequence cannot be learned without interference (Experiment 2) unless one of the sequences can be coded via an alternative, nonspatial dimension (Experiment 3). These results support the notion that spatial location is one module of the implicit learning system and, consequently, that there are no separate processing units for stimulus versus response locations. (PsycINFO Database Record

Disruption of Broca's Area Alters Higher-order Chunking Processing during Perceptual Sequence Learning.

Because Broca's area is known to be involved in many cognitive functions, including language, music, and action processing, several attempts have been made to propose a unifying theory of its role that emphasizes a possible contribution to syntactic processing. Recently, we have postulated that Broca's area might be involved in higher-order chunk processing during implicit learning of a motor sequence. Chunking is an information-processing mechanism that consists of grouping consecutive items in a sequence and is likely to be involved in all of the aforementioned cognitive processes. Demonstrating a contribution of Broca's area to chunking during the learning of a nonmotor sequence that does not involve language could shed new light on its function. To address this issue, we used offline MRI-guided TMS in healthy volunteers to disrupt the activity of either the posterior part of Broca's area (left Brodmann's area [BA] 44) or a control site just before participants learned a perceptual sequence structured in distinct hierarchical levels. We found that disruption of the left BA 44 increased the processing time of stimuli representing the boundaries of higher-order chunks and modified the chunking strategy. The current results highlight the possible role of the left BA 44 in building up effector-independent representations of higher-order events in structured sequences. This might clarify the contribution of Broca's area in processing hierarchical structures, a key mechanism in many cognitive functions, such as language and composite actions.

The neural basis of implicit learning of task-irrelevant Chinese tonal sequence.

The present study sought to investigate the neural basis of implicit learning of task-irrelevant perceptual sequence. A novel SRT task, the serial syllable identification task (SSI task), was used in which the participants were asked to recognize which one of two Chinese syllables was presented. The tones of the syllables were irrelevant to the task but followed an underlying structured sequence. Participants were scanned while they performed the SSI task. Results showed that, at the behavioral level, faster RTs for the sequential material indicated that task-irrelevant sequence knowledge could be learned. In the subsequent prediction test of knowledge of the tonal cues using subjective measures, we found that the knowledge was obtained unconsciously. At the neural level, the left caudate, bilateral hippocampus and bilateral superior parietal lobule were engaged during the sequence condition relative to the random condition. Further analyses revealed that greater learning-related activation (relative to random) in the right caudate nucleus, bilateral hippocampus and left superior parietal lobule were found during the second half of the training phase compared with the first half. When people reported that they were guessing, the magnitude of the right hippocampus and left superior parietal lobule activations was positively related to the accuracy of prediction test, which was significantly better than chance. Together, the present results indicated that the caudate, hippocampus and superior parietal lobule played critical roles in the implicit perceptual sequence learning even when the perceptual features were task irrelevant.

Efficient Robust Speech Authentication Algorithm for Perceptual Hashing Based on Hilbert-Huang Transform

According to the resource-constrained of mobile communication terminal, the traditional broadband speech authentication algorithm cannot satisfy the authentication of a small amount of data, strong robustness and high e‐ciency, etc. This paper, using the short-time stable characteristics of speech signal, proposed an e‐cient robust speech authentication algorithm for perceptual hashing based on Hilbert-Huang Transform (HHT). Firstly, the algorithm obtains to the HHT coe‐cients of each speech frames and constitutes an HHT coe‐cients matrix after pre-processing, framing and adding window to speech signal. Then, the HHT coe‐cients matrix for two-dimensional Discrete Cosine Transform (DCT) generates DCT coe‐cients. It based on DCT coe‐cient characteristics to evaluate its entropy. Finally, a quantization step gets authentication perceptual hash sequence. Experimental results show that the algorithm, compared with the existing methods, has a good robustness and discrimination for content preserving operations, and the short authentication time. Also, it can meet the real-time requirement of the speech perceptual authentication.

Consensus paper: the role of the cerebellum in perceptual processes.

Various lines of evidence accumulated over the past 30 years indicate that the cerebellum, long recognized as essential for motor control, also has considerable influence on perceptual processes. In this paper, we bring together experts from psychology and neuroscience, with the aim of providing a succinct but comprehensive overview of key findings related to the involvement of the cerebellum in sensory perception. The contributions cover such topics as anatomical and functional connectivity, evolutionary and comparative perspectives, visual and auditory processing, biological motion perception, nociception, self-motion, timing, predictive processing, and perceptual sequencing. While no single explanation has yet emerged concerning the role of the cerebellum in perceptual processes, this consensus paper summarizes the impressive empirical evidence on this problem and highlights diversities as well as commonalities between existing hypotheses. In addition to work with healthy individuals and patients with cerebellar disorders, it is also apparent that several neurological conditions in which perceptual disturbances occur, including autism and schizophrenia, are associated with cerebellar pathology. A better understanding of the involvement of the cerebellum in perceptual processes will thus likely be important for identifying and treating perceptual deficits that may at present go unnoticed and untreated. This paper provides a useful framework for further debate and empirical investigations into the influence of the cerebellum on sensory perception.

Incidental sequence learning in a motion coherence discrimination task: How response learning affects perception.

The serial reaction time task (SRTT) is a standard task used to investigate incidental sequence learning. Whereas incidental learning of motor sequences is well-established, few and disputed results support learning of perceptual sequences. Here we adapt a motion coherence discrimination task (Newsome & Paré, 1988) to the sequence learning paradigm. The new task has 2 advantages: (a) the stimulus is presented at fixation, thereby obviating overt eye movements, and (b) by varying coherence a perceptual threshold measure is available in addition to the performance measure of RT. Results from 3 experiments show that action relevance of the sequence is necessary for sequence learning to occur, that the amount of sequence knowledge varies with the ease of encoding the motor sequence, and that sequence knowledge, once acquired, has the ability to modify perceptual thresholds.

Perceptual Speech Hashing Authentication Algorithm Based on Linear Prediction Analysis

According to the situation that traditional speech authentication algorithms are not appropriated for the present speech communication, we proposed a speech authentication algorithm of perceptual hashing which is based on linear forecast analysis (LPC), it can satisfy the requirement of the efficiency and the robustness for the speech authentication. Firstly, the LPC coefficients are optimized, based on the principle of LPC for speech signal, a new prediction coefficients is constituted through combing the energy and the LPC coefficients of a frame; then dividing the prediction coefficient matrix into smaller blocks, and do singular value decomposition (SVD) to the coefficients of each block. Finally, quantifying the formed singular value and getting perceptual hashing sequences. Experiments show that the proposed algorithm has good robustness for content preserving operations, and it doesn’t reduce the efficiency while meeting robustness, it can satisfy the real-time requirement of speech communication. DOI : http://dx.doi.org/10.11591/telkomnika.v12i4.4934

Perceptual Sequence Learning Is More Severely Impaired than Motor Sequence Learning in Patients with Chronic Cerebellar Stroke

Patients with cerebellar stroke are impaired in procedural learning. Several different learning mechanisms contribute to procedural learning in healthy individuals. The aim was to compare the relative share of different learning mechanisms in patients and healthy controls. Ten patients with cerebellar stroke and 12 healthy controls practiced a visuomotor serial reaction time task. Learning blocks with high stimulus-response compatibility were exercised repeatedly; in between these, participants performed test blocks with the same or a different (mirror-inverted or unrelated) stimulus sequence and/or the same or a different (mirror-inverted) stimulus-response allocation. This design allowed to measure the impact of motor learning and perceptual learning independently and to separate both mechanisms from the learning of stimulus-response pairs. Analysis of the learning blocks showed that, as expected, both patients and controls improved their performance over time, although patients remained significantly slower. Analysis of the test blocks revealed that controls showed significant motor learning as well as significant visual perceptual learning, whereas cerebellar patients showed only significant motor learning. Healthy participants were able to use perceptual information for procedural learning even when the rule linking stimuli and responses had been changed, whereas patients with cerebellar lesions could not recruit this perception-based mechanism. Therefore, the cerebellum appears involved in the accurate processing of perceptual information independent from prelearned stimulus-response mappings.

Sequence representation during response preparation in the serial reaction time task

The type of representations involved in implicit learning during the response preparation stage of sequence learning was studied using the response-locked lateralized readiness potential (LRP-R) as an index. Participants performed a modified serial reaction time task on an eight-letter sequence; half were informed to look for patterns in the sequence and half were not. The standard sequence was occasionally replaced by one of two deviant sequences and the LRP-R elicited was analyzed. When comparing across three sequence conditions, namely, a perceptual deviant sequence, a motor deviant sequence, and a standard sequence (as control), the onset latency and the mean amplitude of the LRP-R were similar for all three conditions and for both explicit and implicit learners. The perceptual deviant sequence group showed a longer response preparation time than the motor deviant group and the standard sequence group, but the latter two were not significantly different. The perceptual deviant sequence group showed more negative LRP-R amplitude than the other two groups that did not differ from each other. The finding of similar LRP-R profiles between implicit and explicit learners suggests that stimulus representation (S-S association) is the main form of representation supporting sequence learning in the response preparation stage.

Motor and perceptual sequence learning

The aim was to determine the extent and time course of motor and perceptual learning in a procedural learning task, and the relation of these two processes. Because environmental constraints modulate the relative impact of different learning mechanisms, we chose a simple learning task similar to real-life exercise. Thirty-four healthy individuals performed a visuomotor serial reaction time task. Learning blocks with high stimulus-response compatibility were practiced repeatedly; in between these, participants performed test blocks with the same or a different (mirror-inverted, or new) stimulus sequence and/or with the same or a different (mirror-inverted) stimulus-response allocation. This design allowed us to measure the progress of motor learning and perceptual learning independently. Results showed that in the learning blocks, a steady reduction of the reaction times indicated that - as expected - participants improved their skills continuously. Analysis of the test blocks indicated that both motor learning and perceptual learning were significant. The two mechanisms were correlated (r=0.62, P<0.001). However, their time course was different: the impact of motor learning increased strongly from earlier to later intervals, whereas the progress of perceptual learning was more stable but slower. In conclusion, in a simple visuomotor learning task, participants can learn the motor sequence and the stimulus sequence in parallel. The positive correlation of motor and perceptual learning suggests that the two mechanisms act in synergy and are not alternative opposing strategies. The impact of these two learning mechanisms changes over time: motor learning sets in later and becomes relevant only in the course of training.