View-invariant object category learning, recognition, and search: how spatial and object attention are coordinated using surface-based attentional shrouds

How does the brain learn to recognize an object from multiple viewpoints while scanning a scene with eye movements? How does the brain avoid the problem of erroneously classifying parts of different objects together? How are attention and eye movements intelligently coordinated to facilitate object learning? A neural model provides a unified mechanistic explanation of how spatial and object attention work together to search a scene and learn what is in it. The ARTSCAN model predicts how an object's surface representation generates a form-fitting distribution of spatial attention, or "attentional shroud". All surface representations dynamically compete for spatial attention to form a shroud. The winning shroud persists during active scanning of the object. The shroud maintains sustained activity of an emerging view-invariant category representation while multiple view-specific category representations are learned and are linked through associative learning to the view-invariant object category. The shroud also helps to restrict scanning eye movements to salient features on the attended object. Object attention plays a role in controlling and stabilizing the learning of view-specific object categories. Spatial attention hereby coordinates the deployment of object attention during object category learning. Shroud collapse releases a reset signal that inhibits the active view-invariant category in the What cortical processing stream. Then a new shroud, corresponding to a different object, forms in the Where cortical processing stream, and search using attention shifts and eye movements continues to learn new objects throughout a scene. The model mechanistically clarifies basic properties of attention shifts (engage, move, disengage) and inhibition of return. It simulates human reaction time data about object-based spatial attention shifts, and learns with 98.1% accuracy and a compression of 430 on a letter database whose letters vary in size, position, and orientation. The model provides a powerful framework for unifying many data about spatial and object attention, and their interactions during perception, cognition, and action.     

Recognition of natural scenes from global properties: seeing the forest without representing the trees

Human observers are able to rapidly and accurately categorize natural scenes, but the representation mediating this feat is still unknown. Here we propose a framework of rapid scene categorization that does not segment a scene into objects and instead uses a vocabulary of global, ecological properties that describe spatial and functional aspects of scene space (such as navigability or mean depth). In Experiment 1, we obtained ground truth rankings on global properties for use in Experiments 2-4. To what extent do human observers use global property information when rapidly categorizing natural scenes? In Experiment 2, we found that global property resemblance was a strong predictor of both false alarm rates and reaction times in a rapid scene categorization experiment. To what extent is global property information alone a sufficient predictor of rapid natural scene categorization? In Experiment 3, we found that the performance of a classifier representing only these properties is indistinguishable from human performance in a rapid scene categorization task in terms of both accuracy and false alarms. To what extent is this high predictability unique to a global property representation? In Experiment 4, we compared two models that represent scene object information to human categorization performance and found that these models had lower fidelity at representing the patterns of performance than the global property model. These results provide support for the hypothesis that rapid categorization of natural scenes may not be mediated primarily though objects and parts, but also through global properties of structure and affordance.     

Is banara really a word?

Bowers, Davis, and Hanley (Bowers, J. S., Davis, C. J., & Hanley, D. A. (2005). Interfering neighbours: The impact of novel word learning on the identification of visually similar words. Cognition, 97(3), B45-B54) reported that if participants were trained to type nonwords such as banara, subsequent semantic categorization responses to similar words such as banana were delayed. This was taken as direct experimental support for a process of lexical competition during word recognition. This interpretation assumes that banara has been lexicalized, which predicts that masked form priming for items such as banara-banana should be reduced or eliminated. An experiment is reported showing that the trained novel words produced the same amount of priming as untrained nonwords on both the first and the second day of training, suggesting that the interference observed by Bowers et al was not due to word-on-word competition.     

On the segmentation of Chinese words during reading

Given that there are no spaces between words in Chinese, how words are segmented when reading is something of a mystery. Four Chinese characters, which either constituted one 4-character word or two 2-character words, were shown briefly to subjects. Subjects were quite accurate in reporting the 4-character word, but could usually only report the first 2-character word, demonstrating that word segmentation influences character recognition. The results suggest that even with these simple 4-character strings, there is an element of seriality in reading Chinese words: processing is initially focused at least to some extent on the first word. We also found that the processing of characters that are not consistent with the context is inhibited, suggesting inhibition from word representations to character representations. A simple model of Chinese word segmentation and word recognition is presented to account for the data.     

Word processing in the parafoveal region

This study examined the role of words viewed in the parafoveal region during reading. In contrast to previous work, the present experiments used a reading-aloud paradigm that was postulated to encourage letter-to-sound processing, as is typical for beginning readers and for skilled readers who are reading difficult material. The three experiments in this study examined the role of orthographic and semantic information in the parafoveal region on the processing of a word in the foveal region. For this, two words, one in the foveal region and the other in the parafoveal region, were presented side by side to resemble normal reading. Participants were instructed to read aloud the word on the left side, ignoring the word on the right side. Experiments 1 and 2 showed that the presence of a word in the parafoveal region slowed naming of target words, and that this delay was attributable to linguistic interference. This pattern indicates that the information in the parafoveal region affect the processing of the target. Experiment 3 showed an effect of parafoveal semantic information on processing of the target word. In sum the results of the current study suggest that information in the parafoveal region appears to be linguistically processed but to a weaker degree than the focused word. In sum, the results of the experiments in the current study indicate that the influence of parafoveal information is quite lexical and semantic information in the parafoveal region affects processing of the target in the foveal region.     

How to like yourself better, or chocolate less: Changing implicit attitudes with one IAT task

The current paper introduces a novel feature of implicit association tests (IATs) by demonstrating their potential to change implicit attitudes. We assume that such changes are driven by associative learning mechanisms caused by carrying out an IAT task. Currently, evaluative conditioning appears to be the only widespread paradigm for changing implicit attitudes. An IAT task could provide an alternative. In two experiments, participants initially reacted to only one IAT task. Implicit preferences subsequently assessed with different implicit measures depended on the initial IAT task. This was shown for implicit self-esteem and for implicit attitudes towards well-known candy brands. Findings are discussed in relation to task-order effects in IATs.     

Facilitation of learning of a simultaneous discrimination between rotated patterns by bumblebees

The failure to discriminate between a pattern consisting of four orthogonal bars and the same pattern rotated by 45° has been interpreted in the literature as evidence against pictorial representations in honeybees. This study determines whether prior training can facilitate the discrimination. In Experiment 1, one group of bumblebees was trained with a rewarding spiral pattern (S+) vs. its unrewarding 45° rotation (S−). A second group was trained with two different patterns, the spiral (S+) and the chevron (S−). Both groups were then tested with the spiral and its rotation, both of which were unrewarding. The first group failed in the discrimination while the second succeeded. The same was true when the training period was defined by choice frequency instead of time (Experiment 2). The facilitation due to prior experience was pattern specific (Experiments 3 and 4). These results show perceptual learning in bumblebees and weaken the case against pictorial representations.     

HOLDING ONE ANOTHER (WELL, WRONGLY, CLUMSILY) IN A TIME OF DEMENTIA

Abstract: This essay takes a close look at a species of care that is particularly needed by people with progressive dementias but that has not been much discussed in the bioethics literature: the activity of holding the person in her or his identity. It presses the claim that close family members have a special responsibility to hold on to the demented person's identity for her or him, and offers some criteria for doing this morally well or badly. Finally, it considers how even those with dementia can hold others in their identities, and suggests that this kind of holding too can have great moral worth.     

The Hospital Room as Uncanny: Psychoanalytic Observations and Recommendations for Pastors and Chaplains

This essay in applied psychoanalysis is written for the field of pastoral psychology, and it also has obvious affinities with the medical humanities. The author uses Freud’s (The uncanny. In J. Strachey (Ed. and Trans.), The standard edition of the complete psychological works of Sigmund Freud (Vol. 17, pp. 217–256). Vintage, London, 1919/2001) “The Uncanny” to question the concept of homelike hospital rooms. Instead of making patients feel more comfortable, the authors believes that these rooms could, in some cases, actually increase the anxiety of patients. The author uses Helena Michie’s personal story of her experience of touring a birthing suite to support this argument, as well as some poetry by Billy Collins. The author, however, does not stop with identifying a problem, as he also suggests that pastors and chaplains, when they provide care for their patients, should help them identify and use their own transitional and transformational objects. These objects, of course, will be highly idiosyncratic, and it is precisely this kind of attention—attention to the idiosyncrasies of individuals—that pastors and chaplains should be giving to those in their care. While there is a growing literature on D. W. Winnicott, who coined the term “transitional object,” and Christopher Bollas, who gave us the term “transformational object,” in medical and pastoral circles, the author suggests that attention to and the endorsement of the use of transitional and transformational objects should become a part of hospital policy, if only in chaplaincy handbooks, so as to recognize what many individuals are already doing.     

Early perception of written syllables in French: An event-related potential study

The present study examined whether written syllable units are perceived in first steps of letter string processing. An illusory conjunction experiment was conducted while event-related potentials were recorded. Colored pseudowords were presented such that there was a match or mismatch between the syllable boundaries and the color boundaries. The results showed that congruent stimuli for which the syllable and color boundaries coincided produced a greater positive-going waveform than incongruent stimuli for which the syllable and color boundaries did not coincide. This syllable–color congruency effect was observed to occur both prior to 100 ms, and in a time window commencing at 150 ms. This finding suggests that syllable units are perceived in the initial steps of French visual word processing. Moreover, this study underlines the specificity of the illusory conjunction paradigm as a relevant and powerful tool of investigation of sublexical units that are automatically evoked from word perception.