Adjacent Repetition Research Articles

Применение зондирующих ФКМ-сигналов с нулевой зоной автокорреляции для улучшения качества измерений в РСА

For SARs, a polyphase (p-phase, where p is a prime number) probing signal with a zero autocorrelation zone has been synthesized, which is a train of p phase-code shift keyed (PCSK) pulses coded by complementary sequences of a p-ary D-code with additional phase-code shift-keying of the sub-pulses (discretes) of pulses by an M-sequences. To assess the quality of radar images of point targets and extended surfaces, the levels of the maximum side lobe and one-way integrated correlation noise of the autocorrelation function (ACF) are used, respectively. For this purpose, the work carried out a comparative analysis of the total ACFs of the synthesized ensemble of signals with ensembles of orthogonal chirp and PCSK-signals used in adjacent SAR sounding cycles. The work also considers the problem of superimposition of SAR echo signals from different ranges at a relatively high repetition rate of probing pulses. To assess the level of suppression of recurrent interference from point targets and from extended surfaces, the levels of the maximum side lobe and one-sided integral correlation noise of the cross-correlation function (CCF) are used, respectively. For this purpose, the work carried out a comparative analysis of the total CCFs of the synthesized ensemble of signals with ensembles of orthogonal chirp and PCSK- signals used in the SAR aperture synthesis modes. The use of orthogonal chirp and PCSK-signals makes it possible to successfully suppress false signals from bright point targets from adjacent repetition periods. However, the high level of integral correlation noise of the CCF of orthogonal signals distorts radar images of weakly reflecting surfaces located next to bright extended objects. The indicators of the total correlation characteristics of the synthesized ensemble of signals exceed the corresponding indicators of the total correlation characteristics of the ensemble of orthogonal PCSK-and chirp signals, both without mismatch and with Doppler frequency mismatch. This makes it possible to successfully use an PCSK-signal with a zero autocorrelation zone to improve the quality of radar images and suppress recurrent range interference in SAR.

Six-month-old infants' perception of structural regularities in speech

In order to acquire grammar, infants need to extract regularities from the linguistic input. From birth, infants can detect regularities in speech based on identity relations, and show strong neural activation to syllable sequences containing adjacent repetitions of identical syllables (e.g. ABB: mubaba). Meanwhile, newborns' neural responses to sequences of different syllables (e.g. ABC: mubage, i.e. diversity-based relations) do not differ from baseline. However, this latter ability needs to emerge during development, as most linguistic units, such as words, are composed of highly variable sequences. As infants begin to learn their first word forms at 6 months, we hypothesize that the ability to represent sequences of different syllables might become important for them at this age. Using near-infrared spectroscopy (NIRS), we measured 6-month-old infants' brain responses to repetition- and diversity-based sequences in the bilateral temporal, parietal and frontal areas. We found that 6-month-olds discriminated the repetition- and diversity-based structures in frontal and parietal regions, and exhibited equally strong activation to both grammars as compared to baseline. These results show that by 6 months of age, infants encode sequences with diversity-based structures. They thus provide the earliest evidence that prelexical infants represent difference in speech stimuli, which behavioral studies first attest at 11 months of age.

Extraction of structural regularities by baboons (Papio Papio): Adjacent and nonadjacent repetition patterns differ in learnability.

Several animal species can discriminate between different sequential patterns based on repetitions of items (e.g., ABB vs. ABA), and generalize their performance to sequences made of novel elements but following the same underlying structure. This achievement suggests that these species possess the ability to abstract the sequences structures beyond exemplars. Developmental studies in humans suggest however that adjacent repetition patterns (e.g., ABB) are easier to extract than patterns based on a nonadjacent (e.g., ABA) repetitions. This study addressed this effect of adjacency from a comparative perspective. Seventeen Guinea baboons (Papio papio) were tested with an adaptation of the serial response time task. Results show that baboons successfully learned and generalized both adjacent and nonadjacent repetition patterns after extensive exposure to each pattern in 2 successive experimental phases (Experiment 1). However, when these patterns were presented interleaved within the same experimental phase and at equal frequencies (Experiment 2), or presented successively as in Experiment 1 but with less exposure trials (Experiment 3), baboons showed evidence of learning of the adjacent repetition pattern only. Overall, these data suggest that baboons are more sensitive to adjacent than nonadjacent repetitions. We argue that a strategy based on sole detection of the presence/absence of an adjacent repetition is therefore likely to be adopted by the tested animals in pattern learning studies contrasting adjacent versus nonadjacent repetition patterns, and that future studies may need to avoid this contrast to prevent the use of this strategy. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Repetition inhibition and facilitation effects for visual-verbal stimuli under conditions of concurrent articulation

This study examines the effects of within-sequence repetitions for visually presented consonants under conditions of quiet and concurrent articulation (CA). In an immediate serial recall (ISR) procedure, participants wrote down the six consonants in the order of original presentation. CA reduced serial recall and abolished the phonological similarity effect. However, the effects of within-trial repetitions were broadly similar under quiet and CA. Specifically, adjacent repetitions facilitated recall of the repeated item, whereas spaced repetitions (separated by three intervening items) impaired recall accuracy for the repeated item (i.e., the Ranschburg effect). These data are the first to demonstrate the Ranschburg effect for visual-verbal stimuli under CA.

Hierarchical Processing in Seven‐Month‐Old Infants

Hierarchical structures are crucial to many aspects of cognitive processing and especially for language. However, there still is little experimental support for the ability of infants to learn such structures. Here, we show that, with structures simple enough to be processed by various animals, seven‐month‐old infants seem to learn hierarchical relations. Infants were presented with an artificial language composed of “sentences” made of three‐syllable “words.” The syllables within words conformed to repetition patterns based on syllable tokens involving either adjacent repetitions (e.g., dubaba) or nonadjacent repetitions (e.g., dubadu). Importantly, the sequence of word structures in each sentence conformed to repetition patterns based on word types (e.g., aba‐abb‐abb). Infants learned this repetition pattern of repetition patterns and thus likely a hierarchical pattern based on repetitions, but only when the repeated word structure was based on adjacent repetitions. While our results leave open the question of which exact sentence‐level pattern infants learned, they suggest that infants embedded the word‐level patterns into a higher‐level pattern and thus seemed to acquire a hierarchically embedded pattern.

Learning non-adjacent regularities at age 0 ; 7

One important mechanism suggested to underlie the acquisition of grammar is rule learning. Indeed, infants aged 0 ; 7 are able to learn rules based on simple identity relations (adjacent repetitions, ABB: "wo fe fe" and non-adjacent repetitions, ABA: "wo fe wo", respectively; Marcus et al., 1999). One unexplored issue is whether young infants are able to process both adjacent and non-adjacent repetitions. As the previous studies always compared the two types of repetition structures directly, the ability to learn only one of them was sufficient for successful discrimination in these tasks. The present study reports two experiments, in which we test the ability of infants aged 0 ; 7 to discriminate adjacent and non-adjacent repetition structures against random controls (ABB vs. ABC and ABA vs. ABC). We show that, contrary to some previous proposals, infants aged 0 ; 7 successfully discriminate both repetition types from random controls, but show no spontaneous preference for either of them.

O uso da repetição na escrita pelos surdos

A escrita é uma importante forma de comunicação dos surdos tanto com seus pares quanto com os ouvintes, dada a sua dificuldade em desenvolver a oralidade. Por estarem as marcas de oralidade diretamente relacionadas à coesão textual, este estudo objetivou investigar o uso de repetições na escrita de surdos. Quinze surdos orali%ados, quinze surdos não-oralizados e quinze ouvintes responderam a um questionário analisado quantitativa e qualitativamente em função da ocorrência, tipologia, forma, posição e função das repetições. Os três grupos utilizaram a repetição na escrita. Os dois grupos de surdos apresentaram, majoritariamente, baixa frequência na repetição, integral e adjacente, na escrita. Os oralizados realizaram mais repetições com função de compreensão, enquanto que os não-oralizados realizaram-nas, especialmente, com função de continuidade tópica. Conclui-se que, tal como acontece com os ouvintes, a relação oralidade/escrita ocorre nos surdos, mesmo que eles não tenham tido acesso natural à oralidade da língua. E esta relação ocorre independentemente de eles serem oralizados ou não.

Generalizing linguistic structures under high attention demands.

We explored whether the generalization of rules based on simple structures depends on attention. Participants were exposed to a stream of artificial words that followed a simple syllabic structure (ABA or AAB), overlaid on a sequence of familiar noises. After passively listening, participants successfully recognized the individual words present in the stream among foils, and they were able to generalize the underlying word structure to new exemplars. Yet, when attention was diverted from the speech stream (by requiring participants to monitor the sequence of noises), recognition of the individual words fell dramatically irrespective of word structure, whereas generalization depended on stimulus structure. For structures based on vowel repetitions across nonadjacent syllables (ABA; Experiment 1), generalization was affected by attention. In contrast, for structures based on adjacent repetitions (AAB; Experiment 2), generalization capacity was unaffected by attention. This pattern of results was replicated under favorable conditions for generalization, such as increased token variability and the implementation of the rule over whole syllables (Experiments 3 and 4). These results suggest a differential effect of attention on rule learning and generalization depending on stimulus structure.

Joint ml estimation of frame timing and carrier frequency offset for OFDM systems employing time-domain repeated preamble

When a preamble signal is repeated multiple times in OFDM systems, we derive joint maximum likelihood (ML) estimation of the frame timing (FT) and carrier frequency offset (CFO). Unlike conventional estimators which use correlation of adjacent repetition patterns only or some specific sets of patterns, the joint ML estimation exploits correlation of any pair of repetition patterns, providing optimized performance. To reduce the implementation complexity involved in the joint ML estimation, we also propose a near-ML estimation method that separates estimation of the FT and the CFO. The performance of the proposed methods is verified by computer simulation.

Effects of session and intrasession repetition on individual power law exponents

Number of presentations of the stimulus series was manipulated to choose between response bias and transitory memory theories of individual differences in power function exponents. Four groups of 15 subjects gave magnitude estimations of circle areas in two sessions separated by 1 week. The number of first session presentations for a group was one, two, four, or eight; all received three second session repetitions. Interrepetition correlations of exponents for individuals for adjacent repetitions, within and across sessions, were significant, indicating reliable subject differences. Correlations remained stable over presentations and were similar across groups, suggesting little effect due to repetition. Correlations between sessions did decrease, as the memory hypothesis would predict, but not significantly. Results were interpreted as favorable to the response bias hypothesis but a rapid learning explanation could not be ruled out.

The role of left-right orientation in interhemispheric matching of visual information

Three experiments are described in which Ss matched left- or right-pointing arrowheads presented simultaneously in each visual field. In the first two, they were instructed to press one button as quickly as possible if the stimuli were the same and another if they were mirror images. In the third experiment, they pressed a single button only if the stimuli were the same on half the trials and only if they were mirror images on the other half. This experiment also included a control condition using up- and down-pointing arrowheads. In all three experiments, “same” RTs were shorter than “mirror“ RTs, suggesting that left-right orientation is preserved, rather than mirror-reversed, in interhemispheric matching. This result is also contrary to previous evidence that left-right symmetry is perceptually more salient than adjacent repetition of the same pattern.