Selective learning enabled by intention to learn in sequence learning

This study investigated whether a target sequence that people intend to learn is learned selectively when it is interleaved with another (non-target) sequence. Three experiments used a serial reaction time task in which different spatial and color stimuli occurred alternately. Each of the two interleaved sequences had structural regularity. Participants in an intentional learning group were instructed to learn the target (spatial) sequence whereas those in an incidental learning group were not. In Experiments 1 and 2 spatial and color sequences were correlated. Results showed that the intentional group learned the spatial sequence better than the incidental group and learned it independently of the color sequence, whereas the incidental group learned the two sequences as a combined sequence. In Experiment 3 the sequences were uncorrelated. Results showed that the intentional group was no longer superior in learning the spatial sequence. Findings indicate that the intention to learn a target sequence enables selective learning of it only when it is correlated with a non-target sequence.     

Judgments of the duration of visually marked empty time intervals: Linking perceived duration and sensitivity

The capability of subjects to categorize (as short or long) visually marked empty time intervals was investigated in three experiments. Two visual signals, located 18° to the left (L) and to the right (R) of a fixation point in the visual field, established four marking conditions, two unilaterally presented (L-L and R-R) and two bilaterally presented (L-R and R-L). In Experiments 1 and 2, the results show that discrimination is better with unilateral sequences than with bilateral sequences and that the perceived duration is longer with an L-R than with an R-L sequence. In addition, Experiment 2 shows that, in comparison with a condition in which Markers 1 and 2 remain identical for a complete session, varying the markers from trial to trial does not decrease discrimination. Also, Experiment 2 shows that discrimination is better when both visual markers are presented at fovea than it is in the unilateral conditions. Experiment 3 shows that bilateral intervals are perceived as being longer and are better discriminated than are intervals marked by an intermodal sequence (auditory-visual or visual-auditory). The general discussion reports the implications of having different perceived duration and sensitivity levels, in various marker-type conditions, for an internal-clock hypothesis. Some implications of these results for a lateralized-timer hypothesis are also discussed.     

Attentional holism in visual word processing

Summary Decisions about the identity of an entire word are made more quickly than decisions about the identity of a letter within a word. Explanations of this whole-word advantage based on the time-course of the activation of different levels of unit detectors have given way to explanations based on how attention is allocated to the output of the detectors. Three studies were carried out to examine the role of attention in the whole-word advantage. In Experiment 1, cues as to the level of decision (whole-word vs. first-letter) facilitated component processing, a finding that suggests word level information is normally the focus of attention. In Experiment 2, identification of a probe item to the right of a display was longer when subjects prepared for a first-letter rather than a whole-word decision. That is, the spatial extent of attention is wider for whole-word decisions. In Experiment 3, probe latencies were longer when subjects prepared for a whole-word decision than when they prepared for a signalled probe trial. Preparation for a whole-word decision is not automatic in the sense of being free of capacity demands. The overall pattern of results leads to the conclusion that the whole-word advantage is an instance of attentional holism.     

Individual differences in procedures for knowledge acquisition from maps

This study investigated the procedures subjects use to acquire knowledge from maps. In Experiment 1, three experienced and five novice map users provided verbal protocols while attempting to learn a map. The protocols suggested four categories of processes that subjects invoked during learning: attention, encoding, evaluation, and control. Good learners differed from poor learners primarily in their techniques for and success at encoding spatial information, their ability to accurately evaluate their learning progress, and their ability to focus attention on unlearned information. An analysis of the performance of experienced map users suggested that learning depended on particular procedures and not on familiarity with the task. In Experiment 2, subjects were instructed to use (a) six of the effective learning procedures from Experiment 1, (b) six procedures unrelated to learning success, or (c) their own techniques. The effective procedures set comprised three techniques for learning spatial information, two techniques for using self-generated feedback to guide subsequent study behaviors, and a procedure for partitioning the map into sections. Subjects using these procedures performed better than subjects in the other groups. In addition, subjects' visual memory ability predicted the magnitude of the performance differential.     

Discrepancy detection and vulnerability to misleading postevent information

When people are exposed to misleading details after a witnessed event, they often claim that they saw the misleading details as part of the event. We refer to this as themisinformation effect. In four experiments, involving 570 subjects, we explored the role that discrepancy detection plays in the misinformation effect. Experiment 1 showed that subjects who naturally read a post-event narrative more slowly were more resistant to the effects of misleading information contained in the narrative. In Experiment 2, subjects who naturally read more slowly were more likely to detect a discrepancy between what they were reading and what was stored in their memory. In Experiment 3, subjects who were instructed to read slowly were more likely to detect a discrepancy than were those who were instructed to read quickly. In Experiment 4, subjects who were instructed to read slowly were more resistant to misleading postevent information. Taken together, these results suggest that longer reading times are associated with a greater scrutiny of postevent information. This leads to an increased likelihood that discrepancies will be detected and that the misinformation will be resisted.     

Tracking simple and complex sequences

We address issues of synchronization to rhythms of musical complexity. In two experiments, synchronization to simple and more complex rhythmic sequences was investigated. Experiment 1 examined responses to phase and tempo perturbations within simple, structurally isochronous sequences, presented at different base rates. Experiment 2 investigated responses to similar perturbations embedded within more complex, metrically structured sequences; participants were explicitly instructed to synchronize at different metrical levels (i.e., tap at different rates to the same rhythmic patterns) on different trials. We found evidence that (1) the intrinsic tapping frequency adapts in response to temporal perturbations in both simple (isochronous) and complex (metrically structured) rhythms, (2) people can synchronize with unpredictable, metrically structured rhythms at different metrical levels, with qualitatively different patterns of synchronization seen at higher versus lower levels of metrical structure, and (3) synchronization at each tapping level reflects information from other metrical levels. The latter finding provides evidence for a dynamic and flexible internal representation of the sequence's metrical structure.     

Spatial-frequency-dependent visible persistence and specific reading disability

Visible persistence duration for sine-wave gratings was measured in 9-year-old normal and specific-reading-disabled children. Experiment 1 investigated the influence of stimulus duration on visible persistence. The results demonstrated a Reading Group X Spatial Frequency interaction with disabled readers showing a smaller increase in persistence duration with increasing spatial frequency than controls. This interaction was greatest with stimulus durations longer than 80 msec. In Experiments 2a and 2b persistence was measured across a range of contrasts from .1 to .5. The stimulus durations employed were 100 msec in Experiment 2a and 300 msec in Experiment 2b. In both experiments, increasing contrast decreased persistence duration at 2 and 12 cycles per degree (c/deg) for the control group. In the specific-reading-disabled group, however, contrast had little effect on the persistence of 2-c/deg gratings in either experiment. In Experiment 2a the persistence of the 12-c/deg grating decreased with increasing contrast for both groups. In Experiment 2b contrast had significantly less effect on persistence duration in the specific-reading-disabled group, however, contrast had little effect on the persistence of 2-c/deg ratings in either experiment. In Experiment 2b contrast had significantly less effect on persistence duration in the specific-reading-disabled group than in the control group at 12 c/deg. Consequently, contrast had less effect on persistence in specific-reading-disabled children than in normal readers, especially at durations longer than the "critical duration" for each spatial frequency. Experiment 3 extended this finding to gratings with spatial frequencies of 4 and 8 c/deg. These results indicate a difference between normal and specific-reading-disabled children in cortical visible persistence. Two scores of visual processing were derived from the above experiments. On these scores the reading-disabled children were divided into Visual Disabled Readers (approximately 70%--eight subjects) and Nonvisual Disabled Readers (approximately 30%--four subjects). The percentages of disabled readers in each category remained constant when the sample size was increased to 61 normal and disabled readers.     

Short-term memory for the timing of auditory and visual signals.

Short-term memory for the timing of irregular sequences of signals has been said to be more accurate when the signals are auditory than when they are visual. No support for this contention was obtained when the signals were beeps versus flashes (Experiments 1 and 3) nor when they were sets of spoken versus typewritten digits (Experiments 4 and 5). On the other hand, support was obtained both for beeps versus flashes (Experiments 2 and 5) and for repetitions of a single spoken digit versus repetitions of a single typewritten digit (Experiment 6) when the subjects silently mouthed a nominally irrelevant item during sequence presentation. Also, the timing of sequences of auditory signals, whether verbal (Experiment 7) or nonverbal (Experiments 8 and 9), was more accurately remembered when the signals within each sequence were identical. The findings are considered from a functional perspective.     

Evidence for a conceptual account of same-different discrimination learning in the pigeon

We trained pigeons to peck two different buttons in response to 16-iconsame arrays versus 16-icondifferent arrays. In thesame arrays, the icons were all the same as one another, whereas in thedifferent arrays, the icons were all different from one another. In Experiment 1, we upset the spatial regularities of the displays by disarranging the icons—randomly displacing each icon to reduce the degree of perceptual order. The pigeons’ discriminative performance was unaffected by disarranging. In Experiment 2, spatial regularities were disturbed by varying the rotation of the icons within a display. Again, no disruption in discriminative performance was observed. These and other findings suggest that pigeons treat the 16 icons as either the same or different despite changes in the spatial organization or orientation of the icons, thus implicating a conceptual rather than a perceptual process in same—different discrimination.     

Levels of representation in word processing

Abstract

Four experiments are described examining the effects of words frequency, orthographic structure, and letter spacing on a range of tasks designed to tap different levels of representation in word processing. In Experiment 1, the task was lexical decision. Effects of both frequency (high-frequency words were recognized faster than low-frequency words) and orthographic regularity (illegal non-words were rejected faster than legal non-words) were found. In Experiment 2 subjects had to detect a rotated letter within the letter strings. Effects of orthographic structure emerged, with a marked disadvantage for illegal non-words with respect to the other types of string. No difference was found among high-frequency words, lowfrequency words and legal non-words. In Experiment 3, subjects had to detect a letter elevated above the horizontal plan with respect to the rest of the string. Effects of both spatial arrangement of letters and number of letters were found (spaced strings were responded to less accurately than non-spaced strings and seven-letter extra-spaced strings were responded to slower than the other strings). Neither lexical nor orthograpic variables affected this task. In Experiment 4 subjects had to detect the presence of a bold segment contained in one of the letters in the strings. Performance was unaffected by both lexical and spatial variables. The pattern of results is discussed with reference to a multi-stage model of word recognition in which lexical and spatial variables affect processing at different stages. At a feature map level, in which features are extracted from the discontinuities of light intensities, processing is independent of both spatial and lexical factors. At a letter-shape map level, in which spatial relationships between features are coded, spacing between letters affects encoding. At a graphemic map level, in which letter identities and their relative positions within strings are coded, orthographic variables have an effect. Lexicality and frequency affect only subsequent stages of processing, when stored lexical information is retrieved (e.g. for lexical decision).     

局部注意干扰效应中的眼动特征

采用眼动追踪范式,本研究通过两个实验探讨局部注意干扰效应（LAI）的注意分配特点和机制。实验一采用搜索时间有限的范式,目标呈现70毫秒后消失,在行为和眼动指标上均发现LAI效应：当两个目标距离较近时,反应时增加,正确率降低,总注视时长增长、注视点增加和眼跳速度加快。实验二增加目标呈现时间至1500毫秒以鼓励搜索,产生了比实验一更强烈的LAI效应,且眼跳速度的模式也有不同,说明增加搜索时间并不利于减轻LAI,从而推断LAI的竞争发生在判断阶段,而非搜索和识别目标阶段。     

Orienting numbers in mental space: Horizontal organization trumps vertical

While research on the spatial representation of number has provided substantial evidence for a horizontally oriented mental number line, recent studies suggest vertical organization as well. Directly comparing the relative strength of horizontal and vertical organization, however, we found no evidence of spontaneous vertical orientation (upward or downward), and horizontal trumped vertical when pitted against each other (Experiment 1). Only when numbers were conceptualized as magnitudes (as opposed to nonmagnitude ordinal sequences) did reliable vertical organization emerge, with upward orientation preferred (Experiment 2). Altogether, these findings suggest that horizontal representations predominate, and that vertical representations, when elicited, may be relatively inflexible. Implications for spatial organization beyond number, and its ontogenetic basis, are discussed.     

Orienting numbers in mental space: horizontal organization trumps vertical

While research on the spatial representation of number has provided substantial evidence for a horizontally oriented mental number line, recent studies suggest vertical organization as well. Directly comparing the relative strength of horizontal and vertical organization, however, we found no evidence of spontaneous vertical orientation (upward or downward), and horizontal trumped vertical when pitted against each other (Experiment 1). Only when numbers were conceptualized as magnitudes (as opposed to nonmagnitude ordinal sequences) did reliable vertical organization emerge, with upward orientation preferred (Experiment 2). Altogether, these findings suggest that horizontal representations predominate, and that vertical representations, when elicited, may be relatively inflexible. Implications for spatial organization beyond number, and its ontogenetic basis, are discussed.     

The differential susceptibility of topographic map interpretation to influence from training

Performances on standardized map to landsurface matching tasks were compared following one of three training conditions. Subjects were explicitly instructed to represent the mapped landsurfaces as mental imagery arrays of selected features, and they were presented with sequences of landsurface drawings described as modelling image manipulation processes. Alternatively, subjects were presented with these same sequences, but without explicit instructions that they should be taken as modelling mental processes, or that any particular representational form should be used. Finally, control subjects were presented with neither explicit instructions on processing and representational form nor the sequences of landsurface drawings. Performance differences across the three groups were interpreted in terms of the use of mental imagery being strongly task-determined in such map matching tasks, but the choice of processing strategy being more susceptible to influence from training.     

A comparison of the effects of spatial separation on apparent motion in the auditory and visual modalities

In the present investigation, the effects of spatial separation on the interstimulus onset intervals (ISOIs) that produce auditory and visual apparent motion were compared. In Experiment 1, subjects were tested on auditory apparent motion. They listened to 50-msec broadband noise pulses that were presented through two speakers separated by one of six different values between 0 degrees and 160 degrees. On each trial, the sounds were temporally separated by 1 of 12 ISOIs from 0 to 500 msec. The subjects were instructed to categorize their perception of the sounds as "single," "simultaneous," "continuous motion," "broken motion," or "succession." They also indicated the proper temporal sequence of each sound pair. In Experiments 2 and 3, subjects were tested on visual apparent motion. Experiment 2 included a range of spatial separations from 6 degrees to 80 degrees; Experiment 3 included separations from .5 degrees to 10 degrees. The same ISOIs were used as in Experiment 1. When the separations were equal, the ISOIs at which auditory apparent motion was perceived were smaller than the values that produced the same experience in vision. Spatial separation affected only visual apparent motion. For separations less than 2 degrees, the ISOIs that produced visual continuous motion were nearly equal to those which produced auditory continuous motion. For larger separations, the ISOIs that produced visual apparent motion increased.     

Comparative analysis of movement characteristics during dead-reckoning-based navigation in humans and rats

Human and rat movement organization was investigated as they searched for randomly located rewards without access to visual information. Under dark conditions, rats foraged for randomly located food pellets (Experiment 1). Blindfolded humans were instructed to search for an ostensible hidden coin using a metal detector (Experiment 2). After locating the food pellet, rats carried it back to the refuge, and after a designated searching time, humans were instructed to return to the start location. Although both species exhibited a high degree of similarity in searching path movement organization and ability to return to the start location, disruption of human searching path organization was associated with impairments in returning to the start location. These results support the vestibular "gain" account of movement organization during dead-reckoning-based navigation.     

Influence of single and multiple onset distractors on visual search for singleton targets

In three experiments, we examined attentional and oculomotor capture by single and multiple abrupt onsets in a singleton search paradigm. Subjects were instructed to move their eyes as quickly as possible to a color singleton target and to identify a small letter located inside of it. In Experiment 1, taskirrelevant sudden onsets appeared simultaneously on half the trials with the presentation of the color singleton target. Response times (RTs) were longer when onsets appeared in the display regardless of the number of onsets. Eye-scan strategies were also disrupted by the appearance of the onset distractors, although the proportion of trials on which the eyes were directed to the onsets was the same regardless of the number of onsets. In Experiment 2, we manipulated the time of presentation of two taskirrelevant onsets in order to further examine whether multiple onsets would be attended and fixated prior to attending a color singleton target. Again, subjects made a saccade to a task-irrelevant onset on a substantial proportion of trials prior to fixating the target. However, saccades to the second onset were rare. Experiment 3 served as a replication of Experiment 1 but without the requirement for subjects to move their eyes to detect and identify the singleton target. The RT results were consistent with those in Experiment 1; dual onsets had no larger an effect on response speed than single onset distractors. These data are discussed in terms of the interaction between top-down and bottom-up control of attention and the eyes.     

Influence of single and multiple onset distractors on visual search for singleton targets

In three experiments, we examined attentional and oculomotor capture by single and multiple abrupt onsets in a singleton search paradigm. Subjects were instructed to move their eyes as quickly as possible to a color singleton target and to identify a small letter located inside of it. In Experiment 1, task-irrelevant sudden onsets appeared simultaneously on half the trials with the presentation of the color singleton target. Response times (RTs) were longer when onsets appeared in the display regardless of the number of onsets. Eye-scan strategies were also disrupted by the appearance of the onset distractors, although the proportion of trials on which the eyes were directed to the onsets was the same regardless of the number of onsets. In Experiment 2, we manipulated the time of presentation of two task-irrelevant onsets in order to further examine whether multiple onsets would be attended and fixated prior to attending a color singleton target. Again, subjects made a saccade to a task-irrelevant onset on a substantial proportion of trials prior to fixating the target. However, saccades to the second onset were rare. Experiment 3 served as a replication of Experiment 1 but without the requirement for subjects to move their eyes to detect and identify the singleton target. The RT results were consistent with those in Experiment 1; dual onsets had no larger an effect on response speed than single onset distractors. These data are discussed in terms of the interaction between top-down and bottom-up control of attention and the eyes.     

Discriminating time intervals presented in sequences marked by visual signals.

This article presents the results of three experiments on the discrimination of time intervals presented in sequences marked by brief visual signals. In Experiment 1A (continuous condition), the participants had to indicate whether, in a series of 2-4 intervals marked by 3-5 visual signals, the last interval was shorter or longer than the previous one(s). In Experiment 1B (discontinuous condition), the participants indicated whether, in a presentation of two series of 1-3 intervals, with each series being marked by 2-4 signals, the intervals of the second sequence were shorter or longer than those of the first. Whenever one, two, or three standard intervals were presented, the difference threshold was as high at 150 msec as it was at 300 msec with the continuous method but increased monotonically from 150 to 900 msec with the discontinuous method. With both methods, the increase was well described by Weber's law--the Weber fraction was roughly constant--between 600 and 900 msec (Experiment 2), whereas between 900 and 1,200 msec (Experiment 3), the Weber fraction increased.     

Is there a modality effect? Evidence for visual recency and suffix effects

In Experiment 1, four groups of 16 subjects performed ordered recall of six-syllable lists in both suffix and nonsuffix conditions. Sequential presentation of the lists varied for each group. In the auditory presentation, the syllables were delivered from one location only and were read aloud by the subjects. For the visual, spatially nondistributed presentation, the syllables appeared in one location only and were read silently. For visual, spatially distributed presentations, the syllables were spread out either vertically or horizontally and were read silently. Very robust recency and suffix effects were found in the auditory presentation, as well as in visual, spatially distributed presentations. In Experiment 2, 16 subjects performed ordered recall of visually presented lists with the items spread out vertically and conflicting spatial and temporal orders. A reliable recency effect was found for the final block of trials. In Experiment 3, 16 subjects performed ordered recall in the same conditions as in Experiment 2, except that they were instructed to recall the temporal order in which the spatial positions would be filled in. A bow-shaped curve and a strong recency effect were obtained.