People can store thousands of real-world objects in visual long-term memory with high precision. But are these objects stored as unitary, bound entities, as often assumed, or as bundles of separable features? We tested this in several experiments. In the first series of studies, participants were instructed to remember specific exemplars of real-world objects presented in a particular state (e.g., open/closed; full/empty; etc), and then were asked to recognize either which exemplars they had seen (e.g., I saw this coffee mug), or which exemplar-state conjunctions they had seen (e.g., I saw this coffee mug and it was full). Participants had a large number of within-category confusions, for example misremembering which states went with which exemplars, while simultaneously showing strong memory for the features themselves (e.g., which states they had seen; which exemplars they had seen). In a second series of studies, we found further evidence of independence: participants were very good at remembering which exemplars they had seen independently of whether these items were presented in a new or old state, but the same did not occur for features known to be truly holistically represented. Thus, we find through two lines of evidence that the features of real-world objects that support exemplar discrimination and state discrimination are not bound, suggesting visual objects are not inherently unitary entities in memory.
Prevailing theories of visual working memory assume that each encoded item is stored or forgotten as a separate unit independent from other items. Here, we show that items are not independent, and that the recalled orientation of an individual item is strongly influenced by the summary statistical representation of all items (ensemble representation). We find that not only is memory for an individual orientation substantially biased towards the mean orientation, but the precision of memory for an individual item also closely tracks the precision with which people store the mean orientation (which is, in turn, correlated with the physical range of orientations). Thus, individual items are reported more precisely when items on a trial are more similar. Moreover, the narrower the range of orientations present on a trial, the more participants appear to rely on the mean orientation as representative of all individuals. This can be observed not only when the range is carefully controlled, but also shown even in randomly generated, unstructured displays, and after accounting for the possibility of location-based ‘swap’ errors. Our results suggest that the information about a set of items is represented hierarchically, and that ensemble information can be an important source of information to constrain uncertain information about individuals.
The present study reports alterations of task-based functional brain connectivity in a group of 11 cosmonauts after a long-duration spaceflight, compared to a healthy control group not involved in the space program. To elicit the postural and locomotor sensorimotor mechanisms that are usually most significantly impaired when space travelers return to Earth, a plantar stimulation paradigm was used in a block design fMRI study. The motor control system activated by the plantar stimulation involved the pre-central and post-central gyri, SMA, SII/operculum, and, to a lesser degree, the insular cortex and cerebellum. While no post-flight alterations were observed in terms of activation, the network-based statistics approach revealed task-specific functional connectivity modifications within a broader set of regions involving the activation sites along with other parts of the sensorimotor neural network and the visual, proprioceptive, and vestibular systems. The most notable findings included a post-flight increase in the stimulation-specific connectivity of the right posterior supramarginal gyrus with the rest of the brain; a strengthening of connections between the left and right insulae; decreased connectivity of the vestibular nuclei, right inferior parietal cortex (BA40) and cerebellum with areas associated with motor, visual, vestibular, and proprioception functions; and decreased coupling of the cerebellum with the visual cortex and the right inferior parietal cortex. The severity of space motion sickness symptoms was found to correlate with a post- to pre-flight difference in connectivity between the right supramarginal gyrus and the left anterior insula. Due to the complex nature and rapid dynamics of adaptation to gravity alterations, the post-flight findings might be attributed to both the long-term microgravity exposure and to the readaptation to Earth’s gravity that took place between the landing and post-flight MRI session. Nevertheless, the results have implications for the multisensory reweighting and gravitational motor system theories, generating hypotheses to be tested in future research.
Long-duration spaceflight induces detrimental changes in human physiology. Its residual effects and mechanisms remain unclear. We prospectively investigated the changes in cerebrospinal fluid (CSF) volume of the brain ventricular regions in space crew by means of a region of interest analysis on structural brain scans. Cosmonaut MRI data were investigated preflight (n = 11), postflight (n = 11), and at long-term follow-up 7 mo after landing (n = 7). Post hoc analyses revealed a significant difference between preflight and postflight values for all supratentorial ventricular structures, i.e., lateral ventricle (mean % change ± SE = 13.3 ± 1.9), third ventricle (mean % change ± SE = 10.4 ± 1.1), and the total ventricular volume (mean % change ± SE = 11.6 ± 1.5) (all P < 0.0001), with higher volumes at postflight. At follow-up, these structures did not quite reach baseline levels, with still residual increases in volume for the lateral ventricle (mean % change ± SE = 7.7 ± 1.6; P = 0.0009), the third ventricle (mean % change ± SE = 4.7 ± 1.3; P = 0.0063), and the total ventricular volume (mean % change ± SE = 6.4 ± 1.3; P = 0.0008). This spatiotemporal pattern of CSF compartment enlargement and recovery points to a reduced CSF resorption in microgravity as the underlying cause. Our results warrant more detailed and longer longitudinal follow-up. The clinical impact of our findings on the long-term cosmonauts’ health and their relation to ocular changes reported in space travelers requires further prospective studies.
One of the important sources of failures in visual working memory (VWM) is that individual items can interfere with each other. Here, we tested how two causes of such interference—poor categorical distinctiveness and imperfect feature binding—interact. In three experiments, we showed low and high distinctive objects and tested VWM for objects alone, for locations alone and for object-location conjunctions. We found that low object distinctiveness impairs object recognition and increases the number of object-location binding errors. Also, we dissociated the probabilities that these binding errors are due to recognition impairment or a failure of correct binding. Results show that poor distinctiveness increases binding errors rate only due to lacking recognition but not to binding impairment. Together, our findings suggest that object distinction and object-location binding act upon different components of VWM and are separate sources of interference. This study was funded by RSCF #18-18-00334.
The question of whether visual working memory (VWM) stores individual features or bound objects as basic units is actively debated. Evidence exists for both feature-based and object-based storages, as well as hierarchically organized representations maintaining both types of information at different levels. One argument for feature-based storage is that features belonging to different dimensions (e.g., color and orientations) can be stored without interference suggesting independent capacities for every dimension. Here, we studied whether the lack of cross-dimensional interference reflects genuinely independent feature storages or mediated by common objects. In three experiments, participants remembered and recalled the colors and orientations of sets of objects. We independently manipulated set sizes within each feature dimension (making colors and orientations either identical or differing across objects). Critically, we assigned to-be-remembered colors and orientations either to same spatially integrated or to different spatially separated objects. We found that the precision and recall probability within each dimension was not affected by set size manipulations in a different dimension when the features belonged to integrated objects. However, manipulations with color set sizes did affect orientation memory when the features were separated. We conclude therefore that different feature dimensions can be encoded and stored independently but the advantage of the independent storages are mediated at the object-based level. This conclusion is consistent with the idea of hierarchically organized VWM.
Previous studies have shown that people are good at rapidly estimating ensemble summary statistics, such as the mean size of multiple objects. In the present study, we tested whether these average estimates are based on “raw” retinal representations (proximal sizes) or on how items should appear based on context, such as the viewing distance (distal sizes). In our experiments, observers adjusted the mean size of multiple objects presented at various apparent distances through a stereoscope. In Experiment 1, all items were shifted in depth by the same amount while the adjustable probe stayed at the fixed middle position. We found that presenting ensembles in an apparently remote plane made observers overestimate the mean size, which is consistent with angular sizes being rescaled to distance. In Experiment 2, we presented individual sizes in different planes. While angular sizes and apparent distances were kept controlled across conditions, we only manipulated correlations between them. These manipulations affected the precision of size averaging in line with changes in the range of apparent rather than angular sizes. This pattern is possible only if the visual system rescales each individual size to its distance prior to averaging. Our finding demonstrates that ensemble summaries of basic features, such as size, can be based on quite elaborated representations of multiple objects. We also discuss important implications for size constancy. (PsycINFO Database Record (c) 2019 APA, all rights reserved)
Although the authors propose a useful model for thinking about the structure of memory and memory deficits, their distinction between entities and relational encoding is incompatible with data showing that even individual objects – prototypical ‘entities’ – are made up of distinct features which require binding. Thus, ‘entity’ and ‘relational’ brain regions may need to solve fundamentally the same problems.
The knowledge of target features can be used to guide attention in many conjunction searches in a top-down manner. For example, in search for a red vertical line among blue vertical and red horizontal lines, observers can guide attention toward all red items and all vertical items. Items with both features would gain greater activation. It could be that attention is guided to the group of red items and the group of vertical items with items neatly divided into those with a target feature and those without. Alternatively, attention might be guided to any reddish and relatively vertical items, with no grouping. We tested whether clear, categorical groups were useful in guided search. Observers searched for color-orientation (Experiment 1) or length-orientation (Experiment 2) conjunction targets. Distractors could form two segmentable groups (e.g blue steep and red flat) or distractors could be “non-segmentable” varying from red to blue and steep to flat discouraging grouping and increasing overall heterogeneity. We found that, when the target was present, the searches were quite efficient in Experiment 1 (~9–14 ms/item) and more efficient in Experiment 2 (~0–6 ms/item). Target-present slopes were not affected by “segmentability” manipulations. However, target-absent slopes were less efficient if one of the dimensions was “non-segmentable” (especially in length-orientation conjunctions). In Experiment 3, we demonstrated that search in “non-segmentable” conjunction sets search no less and could be even more efficient than search in “non-segmentable” feature search. Our results suggest that attention is directly guided by the overlap between top-down activation signals corresponding to target features. The guidance mechanism bypasses grouping and segmentation cues that are very important in other tasks like scene parsing and object recognition.
Top-down guidance of visual search is an issue of continuous discussions (e.g. Wolfe, Horowitz, 2017). However, it’s still unclear when guidance emerges in the course of individual development, and whether the fronto-parietal brain network, which underpins attentional control, is necessary for the attentional guidance. Although there were a number of experiments studying visual search in children, to our knowledge no study directly confronted conditions, under which adults do and do not demonstrate guided search, in younger populations. In our experiment, we compared feature search, guided conjunction search and unguided conjunction search in 20 young adults (university students, mean age 18.5) and 20 junior schoolchildren (7.5–9.5 years old, mean age 8.5). The two groups performed three randomized blocks of the standard visual search task, searching for a target “fox’s house” among distractor houses and receiving feedback after each trial. The target house differed from distractors only in color (feature search), in color and shape (conjunction search), or was defined as a specific combination of two colors (conjunction search with no possibility of top-down guidance). Set sizes of 4, 7, and 10 stimuli were used, with only a half of the trials containing a target. Our hypothesis was that in adults we would observe top-down regulation of the conjunction search, whereas in children the search besides the feature search condition will be equally inefficient, because of the fron-to-parietal network immaturity (e.g. Astle et al., 2015). Surprisingly, the overall pattern of results in all three conditions was the same in children and adults, with pronouncedly more efficient conjunction search as compared to the unguided search, although children were significantly (and proportionally) slower in all types of search. This allows concluding that top-down attentional guidance is already fully present in junior schoolchildren.
The visual system can represent multiple objects in a compressed form of ensemble summary statistics (such as object numerosity, mean, and feature variance/range). Yet the relationships between the different types of visual statistics remain relatively unclear. Here, we tested whether two summaries (mean and numerosity, or mean and range) are calculated independently from each other and in parallel. Our participants performed dual tasks requiring a report about two summaries in each trial, and single tasks requiring a report about one of the summaries. We estimated trial-by-trial correlations between the precision of reports as well as correlations across observers. Both analyses showed the absence of correlations between different types of ensemble statistics, suggesting their independence. We also found no decrement (except that related to the order of report explained by memory retrieval) in performance in dual compared to single tasks, which suggests that two statistics of one ensemble can be processed in parallel.
The study continues the exploration of the contribution of creative perception to creative potential. Creative potential was operationalized as divergent thinking and measured by the Abbreviated Torrance Test for Adults. Creative perception was operationalized as a preference for complexity and asymmetry and was assessed by a standard Barron-Welsh Art Scale. Sixty-five undergraduate college students participated in the study. Preference for complexity and asymmetry was found to make a measurable contribution to the elaboration trait of divergent thinking. This finding suggests that in addition to the process, product, person, place, persuasion, and potential perspectives, creativity construct can be evaluated from the standpoint of creative perception.
Purpose - This paper investigates relationships among correlates of individual innovative activity: creativity, innovativeness, novelty seeking, and intelligence.
Design/methodology/approach - Data were collected from 202 students of the Higher School of Economics (123 females and 79 males).
Findings- The findings revealed significant relations between intelligence and fluency of participants’ creative performances, as well as novelty seeking and innovativeness.
Research limitations/implications - Limitations include the correlation design, the sample of students, and the self-reported measures for novelty seeking and innovativeness.
Practical implications- The paper proposes a number of implications for researchers and practitioners who deal with innovation. The results of the study can be applied to various procedures and stages of innovation management.
Originality/value – The study contributes to knowledge on psychological correlates of innovation on an individual level, such as creativity, innovativeness, novelty seeking, and intelligence, as well as produces an empirically validated model of the relationships among them.
Numerous studies report that observers are good at evaluating various ensemble statistics, such as mean or range. Recent studies have shown that, in the perception of mean size, the visual system relies on size information individually rescaled to distance for each item (Utochkin & Tiurina, 2018). Here, we directly tested this rescaling mechanism on the perception of variance. In our experiment, participants were stereoscopically shown a sample set of circles with different sizes and in different apparent depths. Then they had to adjust a test set so that the range of sizes to match the range of the sample. We manipulated the correlation between sizes and depth for both samples and tests. In positive size-depth correlation, bigger circles were presented farther and had to seem larger and small circles were presented closer and had to seem smaller; therefore, the apparent range had to increase. In negative size-depth correlation, the apparent range had to decrease, since bigger circles had to become smaller, and vice versa. We tested all possible couplings of correlation conditions between samples and tests. We found that in general, observers tended to overestimate the range of the sample (over-adjusted it on the test). Yet, the strongest underestimation was shown when the sample had a negative correlation and the test had a positive correlation. This pattern is consistent with the prediction following from the idea of rescaling. As the negative correlation reduced an apparent range, participants had to under-adjust the range of a positively correlated test to compensate for the difference in variance impressions. We conclude, therefore, that multiple sizes are automatically rescaled in accordance with their distances and this rescaling can be used to judge ensemble variance.
The adaptation aftereffect (AAE) of mean size suggests that mean size is coded as a basic visual property. Also, size-distance rescaling of individual objects occurs prior to averaging. Because it is unclear whether the AAE is based on rescaled mean size, we tested the degree of AAE as a function the apparent mean size of stimuli presented at different depths. Observers were stereoscopically shown an adapting patch of dots with either a large or small mean size, followed by a brief test circle. Adaptors and tests were presented at a near and a far plane, both in the same or in different planes. Observers then adjusted the size of a probe in the middle plane to match the test size. We found evidence of the AAE and for test size rescaling, but no effect of whether the adaptor and test were presented in the same or in different planes. Our results suggest that the AAE of mean size take places at a lower level of visual processing than size-distance rescaling. This study was funded by RFBR #18-313-00253.
Illusory conjunctions (IC) refer to errors in which an observer correctly reports features present in the display, but incorrectly pairs features or parts from multiple objects. There is a long-standing debate in the literature about the nature of ICs; for example, whether they arise from the lack of focused attention (Treisman & Schmidt, 1982) or from lossy peripheral representations (Rosenholtz et al., 2012). Here, we test the hypothesis that the occurrence of ICs relates to spatial uncertainty of features falling within the same noisy “window”. According to this idea, ICs occur when the spatial uncertainty is large compared to the distance between items, causing confusion over which features belong to which item. In Experiment 1, we directly measured the spatial noise at 3°, 6°, 9°, 12° from fixation. A compact “crowd” of four dots briefly appeared, followed by the presentation of a probe circle at various distances from the “crowd”. Observers had to respond whether any dot had fallen within the probed region. The probability of perceiving the dots as outside the probe as a function of distance provides a measure of spatial noise as a function of eccentricity. In Experiment 2, we presented four differently colored and oriented bars, located on an invisible circle with a diameter varying from 1° to 3.5° (the “separation”), and centered at one of three eccentricities (4°, 8°, 12°). Participants had to report the color, orientation, and location of any of the bars. The number of correct answers, guesses (reporting non-presented features), and ICs were estimated. The number of IC increased with eccentricity and decreased with separation. There is good resemblance between the spatial noise and the IC pattern. We conclude that there can be an overlap between the mechanisms of spatial localization and IC in peripheral vision.
We previously showed that people can discriminate multiple intermixed groups of objects based on "segmentability," large gaps between values in feature distributions forming several peaks. Here, we test whether such discrimination is based on local or global sampling. Two arrays of lines of various orientation (O) and length (L) were presented; both had identical feature distributions but opposite directions of O-L correlations. These sets consisted of either 14 lines near both meridians or 32 lines filling rectangular regions; participants had to determine boundary orientation between the sets with different O-L correlations. We found that displays with both O and L segmentable provide better discrimination than nonsegmentable ones and an advantage of 32-line sets. This suggests that the segmentation of spatially mixed objects is global sampling of lots of items based on full-scale feature statistics rather than local sampling near a potential boundary.
It has been shown that multiple objects can be efficiently represented as ensemble summary statistics, such as the average. Recently, Kanaya et al. (2018) demonstrated the amplification effect in the perception of average. Their participants judged the mean size or temporal frequency of ensembles, and they tended to exaggerate their estimates, especially larger set sizes. Kanaya et al. explained it by non-exhaustive sampling mechanism favoring ~sqrt(N) most salient items, which are either largest or most frequently ones. But how do the rest of elements contribute to ensemble perception? In our study, we used orientation averaging (which does not have any inevitably salient values) and manipulated the salience of individual items via size. Participants had to adjust the average orientation of 4, 8, or 16 triangles. We measured systematic biases, like Kanaya et al. (2018), and SD of errors that are known to correlate with the physical ensemble range. In Experiment 1, most clockwise elements could be bigger, counterclockwise, middle, or all elements were same-size. We found strong clockwise and counterclockwise biases in the corresponding conditions. The biases increased with set size replicating Kanaya et al. (2018). But we found no SD difference between the conditions suggesting that all items were somehow taken into account. In Experiment 2, we compared distributions with same ranges (full-sets) but salient elements being middle or extreme (most clockwise and counterclockwise). We used distribution with only middle elements or only extremes as controls (half-sets). We found that SD in the full-sets were greater than in the middle half-sets and smaller than in the extreme half-sets suggesting that all items were taken into account. We also found that SD in the extreme full-sets were greater than in the middle full-sets in large set size. We conclude that both exhaustive and amplification types of sampling work in averaging.