Representing visual recursion does not require verbal or motor resources

The ability to form and use recursive representations while processing hierarchical structures has been hypothesized to rely on language abilities. If so, linguistic resources should inevitably be activated while representing recursion in non-linguistic domains. In this study we use a dual-task paradigm to assess whether verbal resources are required to perform a visual recursion task. We tested participants across 4 conditions: (1) Visual recursion only, (2) Visual recursion with motor interference (sequential finger tapping), (3) Visual recursion with verbal interference – low load, and (4) Visual recursion with verbal interference – high load. Our results show that the ability to acquire and use visual recursive representations is not affected by the presence of verbal and motor interference tasks. Our finding that visual recursion can be represented without access to verbal resources suggests that recursion is available independently of language processing abilities.     

Manipulation of visual information does not change the accuracy of distance estimation during a blindfolded walking task

While humans rely on vision during navigation, they are also competent at navigating non-visually. However, non-visual navigation over large distances is not very accurate and can accumulate error. Currently, it is unclear whether this accumulation of error is due to the visual estimate of the distance or to the locomotor production of the distance. In a series of experiments, using a blindfolded walking test, we examine whether enhancing the visual estimate of the distance to a previously seen target, through environmental enrichment, visual imagery, or repeated exposure would improve the accuracy of blindfold navigation across different distances. We also attempt to decrease the visual estimate in order to see if the opposite effect would occur. Our results would indicate that manipulation of the static visual distance estimate did not change the navigation accuracy to any great extent. The only condition that improved accuracy was repeated exposure to the environment through practice. These results suggest that error observed during blindfold navigation may be due to the locomotor production of the distance, rather than the visual process.     

Incidental encoding of numerosity in visual long-term memory

The visual system can readily extract numerosity information from brief experiences. This numerical perception is characterized by diminishing accuracy as numerosity increases, and impaired discrimination for similar quantities and large magnitudes. Here we assess whether these properties apply more broadly to numerosity in visual long-term memory. In surprise memory tests, we observed: Remarkable accuracy in estimating the number of repetitions of an exemplar image (Experiment 1a), that this accuracy decreased but remained high when estimating over categories (Experiments 1b and 1c), that numerical discrimination from memory exhibited psychophysical distance and size effects (Experiment 2), that these effects may derive from stored representations rather than post hoc approximation (Experiment 3a), and that they can reflect total elapsed experience in addition to discrete counts (Experiment 3b). Similar to how numerosity is readily extracted during visual perception, our results suggest that numerosity is encoded incidentally in visual long-term memory.     

Incidental learning speeds visual search by lowering response thresholds, not by improving efficiency: evidence from eye movements

When observers search for a target object, they incidentally learn the identities and locations of "background" objects in the same display. This learning can facilitate search performance, eliciting faster reaction times for repeated displays. Despite these findings, visual search has been successfully modeled using architectures that maintain no history of attentional deployments; they are amnesic (e.g., Guided Search Theory). In the current study, we asked two questions: 1) under what conditions does such incidental learning occur? And 2) what does viewing behavior reveal about the efficiency of attentional deployments over time? In two experiments, we tracked eye movements during repeated visual search, and we tested incidental memory for repeated nontarget objects. Across conditions, the consistency of search sets and spatial layouts were manipulated to assess their respective contributions to learning. Using viewing behavior, we contrasted three potential accounts for faster searching with experience. The results indicate that learning does not result in faster object identification or greater search efficiency. Instead, familiar search arrays appear to allow faster resolution of search decisions, whether targets are present or absent.     

Benefit of enactment over oral repetition of verbal instruction does not require additional working memory during encoding

For this research, we used a dual-task approach to investigate the involvement of working memory in following written instructions. In two experiments, participants read instructions to perform a series of actions on objects and then recalled the instructions either by spoken repetition or performance of the action sequence. Participants engaged in concurrent articulatory suppression, backward-counting, and spatial-tapping tasks during the presentation of the instructions, in order to disrupt the phonological-loop, central-executive, and visuospatial-sketchpad components of working memory, respectively. Recall accuracy was substantially disrupted by all three concurrent tasks, indicating that encoding and retaining verbal instructions depends on multiple components of working memory. The accuracy of recalling the instructions was greater when the actions were performed than when the instructions were repeated, and this advantage was unaffected by the concurrent tasks, suggesting that the benefit of enactment over oral repetition does not cost additional working memory resources.     

Spatial localization does not require the presence of local cues

The purpose of this paper is to demonstrate that rats can rapidly learn to locate an object that they can never see, hear, or smell provided it remains in a fixed spatial location relative to distal room cues. Four groups of rats were permitted to escape from opaque water onto a platform which was either just above or just below the water surface, and in either a fixed or varied location. Learning occurred rapidly except for the group for whom the escape platform was below the water surface and moved about from place to place. Transfer tests revealed that a spatial location search strategy was employed by the group for whom the platform was below water but in a fixed location. A second experiment investigated this learning further, revealing instantaneous transfer when the rats were required to approach the platform from a novel starting position. The data of both studies are discussed in relation to recent work on spatial memory in the rat. The concept of the “acuity” of spatial memory is introduced and the procedures used may provide a new approach to comparing spatial memory with classical and instrumental conditioning.     

The detection of temporally defined objects does not require focused attention

Perceptual grouping is crucial to distinguish objects from their background. Recent studies have shown that observers can detect an object that does not have any unique qualities other than unique temporal properties. A crucial question is whether focused attention is needed for this type of grouping. In two visual search experiments, we show that searching for an object defined by temporal grouping can occur in parallel. These findings suggest that focused attention is not needed for temporal grouping to occur. It is proposed that temporal grouping may occur because the neurons representing the changing object elements adopt firing frequencies that cause the visual system to bind these elements together without the need for focused attention.     

The detection of temporally defined objects does not require focused attention

Perceptual grouping is crucial to distinguish objects from their background. Recent studies have shown that observers can detect an object that does not have any unique qualities other than unique temporal properties. A crucial question is whether focused attention is needed for this type of grouping. In two visual search experiments, we show that searching for an object defined by temporal grouping can occur in parallel. These findings suggest that focused attention is not needed for temporal grouping to occur. It is proposed that temporal grouping may occur because the neurons representing the changing object elements adopt firing frequencies that cause the visual system to bind these elements together without the need for focused attention.     

Categorical perception of emotional facial expressions does not require lexical categories

Does our perception of others' emotional signals depend on the language we speak or is our perception the same regardless of language and culture? It is well established that human emotional facial expressions are perceived categorically by viewers, but whether this is driven by perceptual or linguistic mechanisms is debated. We report an investigation into the perception of emotional facial expressions, comparing German speakers to native speakers of Yucatec Maya, a language with no lexical labels that distinguish disgust from anger. In a free naming task, speakers of German, but not Yucatec Maya, made lexical distinctions between disgust and anger. However, in a delayed match-to-sample task, both groups perceived emotional facial expressions of these and other emotions categorically. The magnitude of this effect was equivalent across the language groups, as well as across emotion continua with and without lexical distinctions. Our results show that the perception of affective signals is not driven by lexical labels, instead lending support to accounts of emotions as a set of biologically evolved mechanisms.     

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.     

Attention-referenced visual representations: evidence from impaired visual localization

Spatial representations in the visual system were probed in 4 experiments involving A. H., a woman with a developmental deficit in localizing visual stimuli. Previous research (M. McCloskey et al., 1995) has shown that A. H.'s localization errors take the form of reflections across a central vertical or horizontal axis (e.g., a stimulus 30 degrees to her left localized to a position 30 degrees to her right). The present experiments demonstrate that A. H.'s errors vary systematically as a function of where her attention is focused, independent of how her eyes, head, or body are oriented, or what potential reference points are present in the visual field. These results suggest that the normal visual system constructs attention-referenced spatial representations, in which the focus of attention defines the origin of a spatial coordinate system. A more general implication is that some of the brain's spatial representations take the form of coordinate systems.     

Short-term retention of visually presented stimuli: some evidence of visual encoding.

Subjects saw two visual stimuli on each trial, separated by an interval ranging from 0 to 8 sec. Each stimulus was composed of a subset of the dots of a 7 × 5 dot matrix. In particular, it was a composite of two patterns, one of which formed a capital English letter and the other of which was an arrangement formed by 8 randomly selected dots. The task was to decide as quickly as possible whether the two stimuli contained the same letter. Under one condition (correlated noise) the same noise pattern was used with both letters; thus the decision as to whether the letters were the same could be based on a test of congruence of the two stimuli, noise and all. Under another condition (uncorrelated noise) the noise patterns differed, assuring that the composite patterns differed, and thus precluding congruence testing as an adequate way to determine whether the two letters were the same. Performance was better (RTs and error rates were smaller) with the correlated noise than with the uncorrelated noise. The result was taken as evidence that visual information was retained in memory, and used to advantage, when the situation clearly warranted the direct comparison of visual patterns.     

The role of meaning in inflection: why the past tense does not require a rule

How do we produce the past tenses of verbs? For the last 20 years this question has been the focal domain for conflicting theories of language, knowledge representation, and cognitive processing. On one side of the debate have been similarity-based or single-route approaches that propose that all past tenses are formed simply through phonological analogies to existing past tenses stored in memory. On the other side of the debate are rule-based or dual-route approaches which agree that phonological analogy is important for producing irregular past tenses (e.g., think-->thought), but argue that regular past tenses (e.g., walk-->walked) are generated via a +ed rule and that a principled account of regular inflection can only be given by recourse to explicit rules. This debate has become a crucial battleground for arguments concerning the necessity and importance of abstract mental rules, embracing not only language processing, but also the of nature cognition itself. However, in centering on the roles of phonological similarity and rules, the past tense debate has largely ignored the possible role of semantics in determining inflection. This paper presents five studies that demonstrate a striking and decisive role of semantic similarity in inflection. In fact, semantic factors appear to be more important in inflection than the grammatical considerations put forward by the dual-route account. Further, these new findings provide a new way of discriminating between the claims of single-route (similarity-based) and dual-route (rule-based) approaches. It appears that inflection is carried out through analogical reminding based on semantic and phonological similarity and that a rule-based route is not necessary to account for past tense inflection.     

Double fusion does not occur in Panum's limiting case: evidence from orientation disparity.

When two lines of different orientations are combined in regular stereograms, the orientation of the resulting line is different from those of the monocular lines. In this study we investigate the percept elicited by orientation disparity in Panum's limiting case. A variant of Panum's limiting case was designed to include orientation disparity. The single line in one half-image tilted leftwards. One of the double lines in the other half-image was parallel to the single line, while the other one tilted rightwards with obliquity one third that of the single line. In this stimulus configuration, if the single line in one half-image fuses with both lines in the other half-image at the same time, both of the two lines perceived after fusion should tilt leftwards. If double fusion does not happen, the two lines should tilt leftwards and rightwards respectively. The results of this study are in agreement with the latter prediction, which implies that double fusion does not occur in this variant of Panum's limiting case.     

The sum of the parts does not equal the whole: evidence from bihemispheric processing.

The 5 experiments in this article examine whether bihemispheric processing can be predicted from the processing observed when information is directed initially to just 1 hemisphere. Ss decided if laterally presented words rhymed with a previously presented central target. Trials varied in the degree to which the information displayed was redundant. On some trials, the same word appeared twice; in others, different words appeared, but they both led to the same decision; and finally, on some trials, different words appeared, each of which also led to a different decision. The patterns found for unilateral and bilateral trials were distinct. Furthermore, the pattern observed on bilateral trials could not be predicted from that found on unilateral trials, suggesting that interhemispheric interaction cannot be surmised from observing a hemisphere processing information in relative isolation.     

Processing similarity does not improve metamemory: evidence against transfer-appropriate monitoring

The transfer-appropriate monitoring (TAM) hypothesis of metamemory predicts that judgment of learning (JOL) accuracy should improve when conditions during JOLs closely match conditions of the memory test. The authors devised 5 types of delayed JOLs for paired associates and varied them along with the type of memory test (cued recall or recognition). If the TAM hypothesis is correct, JOL and test type should interact to influence metamemory. Contrary to TAM, metamemory accuracy did not improve when JOL and test conditions matched but instead tended to vary according to whether the answer was apparent at time of JOL. Memory test scores and JOL magnitude were both greater when the correct target was evident during JOLs. Overall, the results are largely consistent with a monitoring retrieval view of delayed JOLs and do not support TAM as a viable account of JOL accuracy.     

Spatial cognition: evidence from visual neglect

Recent work on human attention and representational systems has benefited from a growing interplay between research on normal attention and neuropsychological disorders such as visual neglect. Research over the past 30 years has convincingly shown that, far from being a unitary condition, neglect is a protean disorder whose symptoms can selectively affect different sensory modalities, cognitive processes, spatial domains and coordinate systems. These clinical findings, together with those of functional neuroimaging, have increased knowledge about the anatomical and functional architecture of normal subsystems involved in spatial cognition. We provide a selective overview of how recent investigations of visual neglect are beginning to elucidate the underlying structure of spatial processes and mental representations.     

When parallel processing in visual word recognition is not enough: new evidence from naming

Low-frequency irregular words are named more slowly and are more error prone than low-frequency regular words (the regularity effect). Rastle and Coltheart (1999) reported that this irregularity cost is modulated by the serial position of the irregular grapheme-phoneme correspondence, such that words with early irregularities exhibit a larger cost than words with late ones. They argued that these data implicate rule-based serial processing, and they also reported a successful simulation with a model that has a rule-based serial component—the DRC model of reading aloud (Coltheart, Rastle, Perry, Langdon, & Ziegler, 2001). However, Zorzi (2000) also simulated these data with a model that operates solely in parallel. Furthermore, Kwantes and Mewhort (1999) simulated these data with a serial processing model that has no rules for converting orthography to phonology. The human data reported by Rastle and Coltheart therefore neither require a serial processing account, nor successfully discriminate among a number of computational models of reading aloud. New data are presented wherein an interaction between the effects of regularity and serial position of irregularity is again reported for human readers. The DRC model simulated this interaction; no other implemented computational model does so. The present results are thus consistent with rule-based serial processing in reading aloud.     

Circadian modulation of conditioned place avoidance in hamsters does not require the suprachiasmatic nucleus

Animals possess the ability to remember both the time of day as well as the location that noxious and potentially dangerous conditions occur. A behavioral expression of this learning is demonstrated in conditioned place avoidance (CPA). CPA is strongest when the time of testing matches the time of day that the prior training had occurred, suggesting the involvement of a circadian oscillator that modulates either memory retrieval or reactivity to the conditioned environment. In these experiments we show that time of day learning persists in the absence of the central circadian clock in the suprachiasmatic nucleus (SCN), demonstrating that memory for time of day is implicit in context conditioning and may involve a circadian oscillator that is distinct from the SCN.