The structure of visual pattern associates and pattern goodness

Two tasks were used with a total set of 126 dot patterns. In one task Ss rated the goodness of each pattern. In another task they produced a dot pattern as an associate to each of the patterns used as a stimulus. The distributions of the associates suggest that the total set of patterns is both partitioned and nested. Groups defined by rotation and reflection are partitioned, thus kept intact. These groups in turn form a series of nested subsets., Both partitioning and nesting produce subsets of different size. The size of these subsets is related to pattern goodness, with good patterns coming from small subsets.     

The effect of goodness onencoding time in visual pattern discrimination

Previous results have implied that pattern goodness, as defined by rotation/reflection equivalence set size, is a determinant of encoding time. A direct test of this implication was made via a discrete RT task using good and poor dot patterns in a two-stimulus discrimination. The following discrimination conditions were used: (1) good vs good; (2) poor vs poor; and (3) good vs poor. Overall RTs for Conditions 1 and 3 were equal, but each was significantly faster than Condition 2. In the first two conditions, there was no difference in RT within pairs and no consistent transitive ordering of the patterns. In Condition 3, however, the good pattern consistently produced the smaller RT. These results indicate that patterns of equal goodness are equally encodable, and the better the pattern, the faster it is encoded. In addition, there was evidence that pattern similarity affects RT.     

Pattern goodness and speed of encoding

Two experiments attempted to resolve a conflict in the literature about whether good patterns are encoded faster than poor patterns in speeded classification tasks. The results showed clear effects of goodness on the memory component of such tasks, but no effect on speed of encoding. The conflicts appear to be due in part to varying encoding requirements of different tasks.     

Hearing what the eyes see: auditory encoding of visual temporal sequences

When the senses deliver conflicting information, vision dominates spatial processing, and audition dominates temporal processing. We asked whether this sensory specialization results in cross-modal encoding of unisensory input into the task-appropriate modality. Specifically, we investigated whether visually portrayed temporal structure receives automatic, obligatory encoding in the auditory domain. In three experiments, observers judged whether the changes in two successive visual sequences followed the same or different rhythms. We assessed temporal representations by measuring the extent to which both task-irrelevant auditory information and task-irrelevant visual information interfered with rhythm discrimination. Incongruent auditory information significantly disrupted task performance, particularly when presented during encoding; by contrast, varying the nature of the rhythm-depicting visual changes had minimal impact on performance. Evidently, the perceptual system automatically and obligatorily abstracts temporal structure from its visual form and represents this structure using an auditory code, resulting in the experience of "hearing visual rhythms."     

Stimulus-specific processing consequences of pattern goodness

Two issues concerning the effects of visual pattern goodness on information processing time were investigated: the role of memory vs. encoding and the role of individual stimulus goodness vs. stimulus similarity. A sequential “same-different” task was used to provide differentiation of target item or memory effects from display item or encoding effects. Experiment 1 used four alternative stimuli in each block of trials. The results showed that good patterns were processed faster than poor patterns for both “same” and “different” responses. Furthermore, the goodness of the target item had a greater effect on reaction time than did the goodness of the display item, indicating that memory is more important than encoding in producing faster processing of good stimuli. Effects of interstimulus similarity on processing time were minimal, although isolation of good stimuli in a similarity space could explain many of the results. Experiment 2 replicated the results of Experiment 1, despite the fact that differences in similarity space had been minimized by using only two alternative stimuli in each block. In addition, the speed of processing a “same” pair was essentially independent of the particular alternative stimulus in a block. These results suggest that in this task, there is a processing advantage for good stimuli that is stimulus specific, with the effect operating primarily in memory.     

视觉工作记忆的巩固加工：时程、模式及机制

在视觉工作记忆加工过程中, 对记忆项目的维持及操作需要将转瞬即逝的感觉输入转换为稳定的记忆表征, 这一加工过程被定义为视觉工作记忆巩固。鉴于巩固在视觉工作记忆中所起到的“门控”作用, 研究者们已经发展出多种研究范式对其可能涉及的运作机制进行探讨。然而, 在不同范式下所观察到的巩固时程存在较大差异, 其所遵循的巩固模式也尚不清晰。此外, 对于巩固所涉及的理论及神经机制亦存在不同的观点。通过对比不同范式的差异性及梳理各方的观点, 可以有效推动这些问题的解决。未来研究除了可以在多种范式下对巩固模式进行验证, 还可以探究注意在巩固中的作用, 以及项目熟悉性等因素会对巩固加工产生何种影响。     

Effects of spatially directed attention on visual encoding

The purpose in this study was to distinguish among possible mechanisms by which focused attention facilitates visual perceptual processing in a cued discrimination task. In two experiments, subjects verified the presence of an X in masked, briefly presented, four-letter arrays. On most trials, subjects were precued to the location of the stimulus array (valid-cue condition); however, sometimes a nonstimulus location was cued (invalid-cue condition). The exposure duration of the stimulus array was varied. In Experiment 1, there was a large effect of cue condition on hit probability, but no effect of cue condition on false alarm probability. In Experiment 2, there was a large effect of cue condition on d'. In both experiments, the stimulus duration needed to reach any given performance level was greater by a constant factor for stimuli in the invalid-cue than it was in the valid-cue condition. This suggests that visual information is acquired (or utilized) more rapidly from attended than from unattended locations.     

The time course of object encoding

Four experiments examined the effects of encoding time on object identification priming and recognition memory. After viewing objects in a priming phase, participants identified objects in a rapid stream of non-object distracters; display times were gradually increased until the objects could be identified (Experiments 1-3). Participants also made old/new recognition judgments about previously viewed objects (Experiment 4). Reliable priming for object identification occurred with 150 ms of encoding and reached a maximum after about 300 ms of encoding time. In contrast, reliable recognition judgments occurred with 75 ms of encoding and continued to improve for encoding times of up to 1200 ms. These results suggest that recognition memory may be based on multiple levels of object representation, from rapidly activated representations of low-level features to semantic knowledge associated with the object. In contrast, priming in this object identification task may be tied specifically to the activation of representations of object shape.     

Effects of semantic priming on visual encoding of pictures

We investigated the effects of semantic priming on initial encoding of briefly presented pictures of objects and scenes. Pictures in four experiments were presented for varying durations and were followed immediately by a mask. In Experiments 1 and 2, pictures of simple objects were either preceded or not preceded by the object's category name (e.g., dog). In Experiment 1 we measured immediate object identification; in Experiment 2 we measured delayed old/new recognition in which targets and distractors were from the same categories. In Experiment 3 naturalistic scenes were either preceded or not preceded by the scene's category name (e.g., supermarket). We measured delayed recognition in which targets and distractors were described by the same category names. In Experiments 1-3, performance was better for primed than for unprimed pictures. Experiment 4 was similar to Experiment 2 in that we measured delayed recognition for simple objects. As in Experiments 1-3, a prime that preceded the object improved subsequent memory performance for the object. However, a prime that followed the object did not affect subsequent performance. Together, these results imply that priming leads to more efficient information acquisition. We offer a picture-processing model that accounts for these results. The model's central assumption is that knowledge of a picture's category (gist) increases the rate at which visual information is acquired from the picture.     

The role of pattern goodness in the reproduction of backward masked patterns.

Four experiments investigated the role of pattern goodness in backward masking using five- and four-dot patterns constructed by placing dots in the cells of a 3 x 3 matrix. In Experiment 1, subjects rated the goodness of these patterns and the results replicated previous work showing that good patterns had few alternatives. In Experiment 2, the dot patterns were the target stimuli in a backward masking task using a variety of masking stimuli. For all masking, good patterns were reproduced more accurately than poor patterns. In Experiment 3, the goodness of the masking stimulus was varied. The results indicated that good patterns were reproduced more accurately (replicating Experiment 2) and that good patterns were less effective as stimulus than were poor patterns. In Experiment 4, a long interstimulus interval which precluded masking was used to determine whether goodness affected encoding or memory. At these intervals, there were no differences among patterns, suggesting that the effect of pattern goodness was on rate of encoding. These results demonstrate the importance of configural properties in pattern perception.     

Temporal characteristics of the effects of visual pattern redundancy on encoding and storage processes: evidence from rapid serial visual presentation

Pattern redundancy is a key concept for representing the amount of internal mental load (encoding efficiency) needed for pattern perception/recognition. The present study investigated how pattern redundancy influences encoding and memory processes in the visual system using a rapid serial visual presentation (RSVP) paradigm. With RSVP, it is well known that participants often fail to detect repetitions of words (repetition blindness, RB). We used this phenomenon as an index of the encoding and storage of visual patterns. In three experiments, we presented patterns with higher and lower redundancy, as defined by Garner’s equivalent set size (ESS). The results showed that RB occurred more frequently for higher redundancy patterns when the temporal distance between the targets was less than 500 ms; this tendency was reversed with longer temporal distances of over 500 ms. Our results suggest that pattern redundancy modulates both the early encoding and subsequent memory processes of a representation.     

Judgment of numerosity: effects of symmetry and goodness in dot pattern arrays

Studies of numerosity judgment characteristically use random dot arrays as targets. A few recent studies have shown concern for the role played by configural properties of the pattern array in the judgment of numerosity. The primary purpose of the present short report was to establish whether amount of whole symmetry and part symmetry in an array affects the accuracy of numerosity judgment. A subsidiary purpose was to explore the relationship between probability of correct judgment of numerosity and independent data on the immediate recallability of the same pattern arrays. Two hundred patterns with array sizes 1–11 and five amounts of whole and part symmetry were used. There were two clear findings. One, that the probability of correct numerosity judgment increases with amount of whole symmetry but not of part symmetry. Two, that such probability scores yield essentially zero correlations with two measures of pattern recallability and with a measure of pattern goodness. The findings are consistent with the arguments (a) that whole symmetry is rapidly abstracted at a very early stage and facilitates parallel processing of numerosity, and (b) that the numerosity of an array is assessed sooner than the spatial locations of the configuration per se can be encoded.     

Effects of redundant visual stimuli on temporal order judgments

Four experiments were conducted in order to compare the effects of stimulus redundancy on temporal order judgments (TOJs) and reaction times (RTs). In Experiments 1 and 2, participants were presented in each trial with a tone and either a single visual stimulus or two redundant visual stimuli. They were asked to judge whether the tone or the visual display was presented first. Judgments of the relative onset times of the visual and the auditory stimuli were virtually unaffected by the presentation of redundant, rather than single, visual stimuli. Experiments 3 and 4 used simple RT tasks with the same stimuli, and responses were much faster to redundant than to single visual stimuli. It appears that the traditional speedup of RT associated with redundant visual stimuli arises after the stimulus detection processes to which TOJs are sensitive.     

Effects of stimulus probability and visual similarity on stimulus encoding

Visual similarity, stimulus probability, and stimulus contrast were manipulated in two memory-scanning experiments to determine how stimulus probability affects encoding. Two hypotheses were tested: The first, a featural facilitation hypothesis, localizes the effect of stimulus probability on feature extraction; the second claims that stimulus probability has its effect on stimulus recognition. In both experiments, visual similarity was found to slow encoding, particularly under low-contrast conditions. This effect was larger for low probability stimuli than for high probability stimuli and increased as the difference in probability between two visually similar stimuli increased. These results are inconsistent with the featural facilitation hypothesis, but can be explained in terms of differential priming of internal recognition responses for members of the stimulus set, such that more probable members are more easily recognized.     

The temporal course of the frustration effect

General activity subsequent to reward (R) and nonreward (N) was monitored at 5-sec intervals with a stabilimeter in the runway goal box. Activity of never-rewarded control Ss was also measured. In Expt 1 it was found that the frustration effect (difference between N- and R-trial activities) disappeared after about 40 sec of goal box confinement. This disappearance of the frustration effect was due to activity increase on R trials rather than activity decrease on N trials as a function of time. Comparison of N-trial activity with control group activity indicated that frustration does not dissipate within 60 sec. Expt 2 investigated activity following reward and nonreward as a function of reward magnitude. Evidence from these experiments suggests that the late R-trial activity increase results from frustration, possibly conditioned to apparatus cues on N trials.     

The temporal dynamics of visual object priming

Priming reflects an important means of learning that is mediated by implicit memory. Importantly, priming occurs for previously viewed objects (item-specific priming) and their category relatives (category-wide priming). Two distinct neural mechanisms are known to mediate priming, including the sharpening of a neural object representation and the retrieval of stimulus–response mappings. Here, we investigated whether the relationship between these neural mechanisms could help explain why item-specific priming generates faster responses than category-wide priming. Participants studied pictures of everyday objects, and then performed a difficult picture identification task while we recorded event-related potentials (ERP). The identification task gradually revealed random line segments of previously viewed items (Studied), category exemplars of previously viewed items (Exemplar), and items that were not previously viewed (Unstudied). Studied items were identified sooner than Unstudied items, showing evidence of item-specific priming, and importantly Exemplar items were also identified sooner than Unstudied items, showing evidence of category-wide priming. Early activity showed sustained neural suppression of parietal activity for both types of priming. However, these neural suppression effects may have stemmed from distinct processes because while category-wide neural suppression was correlated with priming behavior, item-specific neural suppression was not. Late activity, examined with response-locked ERPs, showed additional processes related to item-specific priming including neural suppression in occipital areas and parietal activity that was correlated with behavior. Together, we conclude that item-specific and category-wide priming are mediated by separate, parallel neural mechanisms in the context of the current paradigm. Temporal differences in behavior are determined by the timecourses of these distinct processes.     

Enhancing visual working memory encoding: The role of target novelty

Perceptual salience improves the encoding of information into visual working memory (WM). However, the factors that contribute to this facilitation effect are not well understood. This study tested the influence of target familiarity on WM encoding. In each trial, participants were presented with either one or three targets and asked to encode their locations into WM. In Experiment 1, target familiarity was manipulated by presenting either an upright (familiar target) or upside-down (unfamiliar/novel target) A. Increasing the novelty of the targets led to improved performance in the spatial WM task. Experiment 2 showed that participants were faster in responding to novel versus familiar targets in a spatial detection task. Experiment 3 demonstrated that the beneficial effect of target novelty on WM encoding was not driven by differences in low-level features. Our results suggest that target novelty enhances the processes required for WM encoding, just as it facilitates perceptual processing.