A program for generating randomized simple and context-sensitive sequences

This article introduces Sequence Generation 2008 (SeqGen2008), a Windows-based sequence generator. SeqGen2008 can generate simple sequences satisfying user-defined event probabilities or frequencies. The program can also generate context-sensitive sequences satisfying user-defined transition matrices that specify the probabilities or frequencies with which distinct events are to follow specific contexts. An analysis of the properties and behavior of the algorithms employed by SeqGen2008 reveals that the algorithms are unbiased in their generation of sequences.     

Absolute identification with simple and complex stimuli

It is well known that people can perfectly identify only a handful of distinct unidimensional stimuli, such as line lengths, but can identify thousands of complex stimuli, such as letters and words. This result is consistent with capacity limits in identifying unidimensional stimuli but not complex stimuli. The experiments reported here tested this theoretical dissociation using Luce's (1963) Similarity Choice Model to measure the psychological distance between stimuli in line-length-identification and letter-identification tasks. The psychological distance between line-length stimuli decreased with the number of to-be-identified stimuli; this result is concordant with capacity limits in unidimensional absolute identification. Surprisingly, the opposite result held in letter identification. Psychological distance between letters increased with an increased number of to-be-identified stimuli. This result indicates an opposite type of processing deficit: People process letters more efficiently with more choices.     

Precision and accuracy in the reproduction of simple tone sequences

In four experiments we investigated the precision and accuracy with which amateur musicians are able to reproduce sequences of tones varied only temporally, so as to have tone and rest durations constant over sequences, and the tempo varied over the musically meaningful range of 5-0.5 tones per second. Experiments 1 and 2 supported the hypothesis of attentional bias toward having the attack moments, rather than the departure moments, precisely times. Experiment 3 corroborated the hypothesis that inaccurate timing of short interattack intervals is manifested in a lengthening of rests, rather than tones, as a result of larger motor activity during the reproduction of rests. Experiment 4 gave some support to the hypothesis that the shortening of long interattack intervals is due to mnemonic constraints affecting the rests rather than the tones. Both theoretical and practical consequences of the various findings, particularly with respect to timing in musical performance, are discussed.     

Observation and physical practice: Coding of simple motor sequences

An experiment was conducted to determine the coordinate system used in the development of movement codes during observation and utilized on later physical practice performance of a simple spatial–temporal movement sequence. The task was to reproduce a 1.3-s spatial–temporal pattern of elbow flexions and extensions. An intermanual transfer paradigm with a retention test and two transfer tests was used: a mirror transfer test where the same pattern of muscle activation and limb joint angles was required and a nonmirror transfer test where the visual–spatial pattern of the sequence was reinstated on the transfer test. The results indicated a strong advantage for participants in the physical practice condition when transferred to the mirror condition in which the motor coordinates (e.g., pattern of muscle activation and joint angles) were reinstated relative to transfer performance when the visual–spatial coordinates were reinstated (visual and spatial location of the target waveform). The observation group, however, demonstrated an advantage when the visual–spatial coordinates were reinstated. These results demonstrate that codes based in motor coordinates can be developed relatively quickly for simple rapid movement sequences when participants are provided physical practice, but observational practice limits the system to the development of codes based in visual–spatial coordinates. Performances of control participants, who were not permitted to practise or observe the task, were quite poor on all tests.     

Observation and physical practice: coding of simple motor sequences

An experiment was conducted to determine the coordinate system used in the development of movement codes during observation and utilized on later physical practice performance of a simple spatial-temporal movement sequence. The task was to reproduce a 1.3-s spatial-temporal pattern of elbow flexions and extensions. An intermanual transfer paradigm with a retention test and two transfer tests was used: a mirror transfer test where the same pattern of muscle activation and limb joint angles was required and a nonmirror transfer test where the visual-spatial pattern of the sequence was reinstated on the transfer test. The results indicated a strong advantage for participants in the physical practice condition when transferred to the mirror condition in which the motor coordinates (e.g., pattern of muscle activation and joint angles) were reinstated relative to transfer performance when the visual-spatial coordinates were reinstated (visual and spatial location of the target waveform). The observation group, however, demonstrated an advantage when the visual-spatial coordinates were reinstated. These results demonstrate that codes based in motor coordinates can be developed relatively quickly for simple rapid movement sequences when participants are provided physical practice, but observational practice limits the system to the development of codes based in visual-spatial coordinates. Performances of control participants, who were not permitted to practise or observe the task, were quite poor on all tests.     

Inter-manual transfer and practice: Coding of simple motor sequences

Previous research suggests that movements are represented early in practice in visual-spatial coordinates/codes, which are effector independent, and later in practice in motor coordinates/codes (e.g., joint angles, activation patterns), which are effector dependent. In the present experiments, the task was to reproduce 1.3 s patterns of elbow flexions and extensions. An inter-manual transfer paradigm was used in Experiment 1 and an inter-manual practice paradigm was used in Experiment 2. The present results clearly indicated a strong advantage of effector transfer when the motor coordinates available during acquisition were reinstated (Experiment 1) and demonstrate that inter-manual practice with the same motor coordinates results in enhanced retention performance relative to transfer and practice where the same visual-spatial coordinates are used. These results demonstrate that the more effective movement code (motor or visual-spatial) is dependent on the movement sequence characteristics (e.g., difficulty, number of elements, and mode of control [preplanned or on-line]). These results are also interesting because they indicate, contrary to previous findings with more complex movement sequences, that an effective motor code can be developed relatively early in practice for rapid movement sequences.     

Synthesizing complex sensations from simple components

The target article suggests that taste is not based on the traditional four basic tastes, but rather is a continuum subserved by cross-fiber integration. This commentary describes evidence indicating that the traditional concept is valid, and that with suitable precautions, it is possible to match natural substances using mixtures representing fundamental tastes.     

Preprogramming vs. on-line control in simple movement sequences

In the present experiment the acceleration traces produced during a repetitive arm extension/flexion movement were measured in addition to the RT required to initiate such a movement. The speed at which this task was completed as well as the number of extension/flexion segments were varied to allow for either preprogramming or on-line control. Evidence from the acceleration traces and the RT data suggested that the movements completed as quickly as possible were preprogrammed; whereas, those completed more slowly were controlled on-line. Furthermore, the topologies of the power spectral density functions from the acceleration traces of each type of movement displayed characteristics typical of these forms of control.     

Visual working memory for simple and complex visual stimuli

Does the magical number four characterize our visual working memory (VWM) capacity for all kinds of objects, or is the capacity of VWM inversely related to the perceptual complexity of those objects? To find out how perceptual complexity affects VWM, we used a change detection task to measure VWM capacity for six types of stimuli of different complexity: colors, letters, polygons, squiggles, cubes, and faces. We found that the estimated capacity decreased for more complex stimuli, suggesting that perceptual complexity was an important factor in determining VWM capacity. However, the considerable correlation between perceptual complexity and VWM capacity declined significantly if subjects were allowed to view the sample memory display longer. We conclude that when encoding limitations are minimized, perceptual complexity affects, but does not determine, VWM capacity.     

Phonological similarity effects in simple and complex span tasks

Three experiments were conducted to examine the effect of phonological similarity in simple and complex memory span tasks. In Experiment 1, participants performed either a simple or a complex span task, and the memoranda within lists were either phonologically similar or distinct. Phonologically similar lists consisted of words that rhymed.The simple span task was word span. There were two complex span tasks; one was the original reading span task, and the other was a variant of reading span in which all the sentences within a list were contextually related. The classic phonological similarity decrement was observed in word span. In contrast, phonological similarity facilitation was observed in both versions of reading span. This facilitation effect was further investigated in Experiment 2 using two new versions of reading span. In Experiment 2, the sentences in reading span were either short or long, and the memoranda were presented separately from, and were unrelated to, the sentences. Again, words within phonologically similar lists rhymed, and again, facilitation was observed. In Experiment 3, phonological similarity was operationalized in terms of feature overlap, rather than rhyme. The classic phonological similarity decrement was still observed in word span, but facilitation was not observed in complex span. The results suggest that phonological similarity, when operationalized using words that rhyme, serves as a list retrieval cue and that complex span tasks are more dependent on cue-driven memory retrieval mechanisms than are simple span tasks.     

Tracking transitional probabilities and segmenting auditory sequences are dissociable processes in adults and neonates

Since speech is a continuous stream with no systematic boundaries between words, how do pre-verbal infants manage to discover words? A proposed solution is that they might use the transitional probability between adjacent syllables, which drops at word boundaries. Here, we tested the limits of this mechanism by increasing the size of the word-unit to four syllables, and its automaticity by testing asleep neonates. Using markers of statistical learning in neonates’ EEG, compared to adult behavioral performances in the same task, we confirmed that statistical learning is automatic enough to be efficient even in sleeping neonates. We also revealed that: (1) Successfully tracking transition probabilities (TP) in a sequence is not sufficient to segment it. (2) Prosodic cues, as subtle as subliminal pauses, enable to recover words segmenting capacities. (3) Adults’ and neonates’ capacities to segment streams seem remarkably similar despite the difference of maturation and expertise. Finally, we observed that learning increased the overall similarity of neural responses across infants during exposure to the stream, providing a novel neural marker to monitor learning. Thus, from birth, infants are equipped with adult-like tools, allowing them to extract small coherent word-like units from auditory streams, based on the combination of statistical analyses and auditory parsing cues.

Research Highlights

• Successfully tracking transitional probabilities in a sequence is not always sufficient to segment it.
• Word segmentation solely based on transitional probability is limited to bi- or tri-syllabic elements.
• Prosodic cues, as subtle as subliminal pauses, enable to recover chunking capacities in sleeping neonates and awake adults for quadriplets.

     

Representation of complex emotional and abstract meanings by simple forms

Using curved and angular line drawings, several investigators found a relation between form and meaning in individuals reared before the age of television. In the present study 60 university students who had been exposed to television from earliest childhood were asked to indicate whether a curved or angular figure best represented each of 40 emotion or abstract concepts. For 36 of the concepts the frequencies were significantly different from a chance level, and it was concluded that television viewing had no adverse effect on the fittingness of form and meaning. Several possible explanations for the phenomenon are discussed.     

Scheduling observational and physical practice: Influence on the coding of simple motor sequences

The main purpose of the present experiment was to determine the coordinate system used in the development of movement codes when observational and physical practice are scheduled across practice sessions. The task was to reproduce a 1,300-ms spatial–temporal pattern of elbow flexions and extensions. An intermanual transfer paradigm with a retention test and two effector (contralateral limb) transfer tests was used. The mirror effector transfer test required the same pattern of homologous muscle activation and sequence of limb joint angles as that performed or observed during practice, and the nonmirror effector transfer test required the same spatial pattern movements as that performed or observed. The test results following the first acquisition session replicated the findings of Gruetzmacher, Panzer, Blandin, and Shea (2011) Gruetzmacher, N., Panzer, S., Blandin, Y. and Shea, C. H. 2011. Observation and coding of simple motor sequences. Quarterly Journal of Experimental Psychology, 64: 1111–1123. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]. The results following the second acquisition session indicated a strong advantage for participants who received physical practice in both practice sessions or received observational practice followed by physical practice. This advantage was found on both the retention and the mirror transfer tests compared to the nonmirror transfer test. These results demonstrate that codes based in motor coordinates can be developed relatively quickly and effectively for a simple spatial–temporal movement sequence when participants are provided with physical practice or observation followed by physical practice, but physical practice followed by observational practice or observational practice alone limits the development of codes based in motor coordinates.     

Indirect assessment of visual working memory for simple and complex objects

Previous research has shown that visual search performance is modulated by the current contents in visual working memory (VWM), even when the contents of VWM are irrelevant to the search task. For example, visual search is faster when the target--rather than a distractor--is surrounded by a shape currently held in VWM. This study uses the modulation of visual search by VWM to investigate properties of VWM. Participants wereasked to remember the color or the shape of novel polygons whose "goodness" of figure varied according to Garner's (1962) rotation and reflection transformation principle. During the memory retention interval, participants searched for a tilted line among vertical lines embedded inside colored polygons. Search was faster when the target--rather than a distractor--was enclosed by the remembered polygons. The congruity effect diminished with increasing memory load and decreasing figure goodness. We conclude that congruity effects in visual search can indirectly assess VWM representation strength.     

Scheduling observational and physical practice: influence on the coding of simple motor sequences

The main purpose of the present experiment was to determine the coordinate system used in the development of movement codes when observational and physical practice are scheduled across practice sessions. The task was to reproduce a 1,300-ms spatial-temporal pattern of elbow flexions and extensions. An intermanual transfer paradigm with a retention test and two effector (contralateral limb) transfer tests was used. The mirror effector transfer test required the same pattern of homologous muscle activation and sequence of limb joint angles as that performed or observed during practice, and the non-mirror effector transfer test required the same spatial pattern movements as that performed or observed. The test results following the first acquisition session replicated the findings of Gruetzmacher, Panzer, Blandin, and Shea (2011) . The results following the second acquisition session indicated a strong advantage for participants who received physical practice in both practice sessions or received observational practice followed by physical practice. This advantage was found on both the retention and the mirror transfer tests compared to the non-mirror transfer test. These results demonstrate that codes based in motor coordinates can be developed relatively quickly and effectively for a simple spatial-temporal movement sequence when participants are provided with physical practice or observation followed by physical practice, but physical practice followed by observational practice or observational practice alone limits the development of codes based in motor coordinates.     

Masked transposition effects for simple versus complex nonalphanumeric objects

When two letters/digits/symbols are switched in a string (e.g., jugde–judge; 1492–1942; *?When two letters/digits/symbols are switched in a string (e.g., jugde-judge; 1492-1942; *?$&-*$?&), the resulting strings are perceptually similar to each other and produce a sizable masked transposition priming effect with the masked priming same-different matching task. However, a parallel effect does not occur for strings of pseudoletters (e.g., [letters in the text]); García-Orza, Perea, & Mu?oz, Quarterly Journal of Experimental Psychology, 63, 1603-1618, 2010). In the present study, we examined whether masked transposition priming is specific to alphanumeric stimuli or whether it also occurs with strings composed of other "objects"-namely, line drawings of common objects (Experiment 1) and geometrical shapes (Experiment 2). Results showed a significant masked transposition priming effect for geometrical shapes (e.g., [geometrical shapes in the text]), but not for line drawings of common objects (e.g., [symbols in the text]). These findings suggest that the mechanism involved in the coding of position in masked priming works only with perceptually simple, familiar "objects" (i.e., letters, numbers, symbols, or geometrical shapes), once their identities have been well ascertained.     

Predictability affects the perception of audiovisual synchrony in complex sequences

The ability to make accurate audiovisual synchrony judgments is affected by the "complexity" of the stimuli: We are much better at making judgments when matching single beeps or flashes as opposed to video recordings of speech or music. In the present study, we investigated whether the predictability of sequences affects whether participants report that auditory and visual sequences appear to be temporally coincident. When we reduced their ability to predict both the next pitch in the sequence and the temporal pattern, we found that participants were increasingly likely to report that the audiovisual sequences were synchronous. However, when we manipulated pitch and temporal predictability independently, the same effect did not occur. By altering the temporal density (items per second) of the sequences, we further determined that the predictability effect occurred only in temporally dense sequences: If the sequences were slow, participants' responses did not change as a function of predictability. We propose that reduced predictability affects synchrony judgments by reducing the effective pitch and temporal acuity in perception of the sequences.     

Age-related effects in interlimb practice on coding complex movement sequences

Hikosaka et al. (1999) proposed that sequential movements are acquired in independent visual-spatial and motor coordinate systems with coding initially represented in visual-spatial coordinates, and later after extended practice in motor coordinates. One aspect of sequence learning that has not been systematically studied, however, is the question of whether or not older adults show the same pattern of coding in inter-limb practice as younger learners. In the present experiment an inter-limb practice paradigm was designed to determine the role that visual-spatial (Cartesian) and motor (joint angles, activation patterns) coordinates play in the coding and learning of a complex movement sequence. Younger and older adults practiced a 16-element movement sequence with one limb on Day 1 and the contra-lateral limb on Day 2. Practice involved the same sequence with either the same visual-spatial or motor coordinates on the two days. Retention tests were conducted on Day 3. Results indicated that keeping the visual-spatial coordinates the same during acquisition resulted in superior retention only for younger adults. Results also indicated the overall slowing of sequential movement production for older adults which appears to result from these participants inability to impose a structure on the sequence. This provides strong evidence that the visual-spatial code plays a dominant role in complex movement sequences and this code is represented in an effector-independent manner for younger adults, but not for older adults.