Grouping Cues Research Articles

Investigating the relationship between subjective perception and unconscious feature integration.

Visual features need to be temporally integrated to detect motion signals and solve the many ill-posed problems of vision. It has previously been shown that such integration occurs in windows of unconscious processing of up to 450 milliseconds. However, whether features are integrated should be governed by perceptually meaningful mechanisms. Here, we expand on previous findings suggesting that subjective perception and integration may be linked. Specifically, different observers were found to group elements differently and to exhibit corresponding feature integration behavior. If the former were to influence the latter, perception would appear to not only be the outcome of integration but to potentially also be part of it. To test any such linkages more systematically, we here examined the role of one of the key perceptual grouping cues, color similarity, in the Sequential Metacontrast Paradigm (SQM). In the SQM, participants are presented with two streams of lines that are expanding from the center outwards. If several lines in the attended motion stream are offset, offsets integrate unconsciously and mandatorily for periods of up to 450 milliseconds. Across three experiments, we presented lines of varied colors. Our results reveal that individuals who perceive differently colored lines as "popping out" from the motion stream do not exhibit mandatory integration but that individuals who perceive such lines as part of an integrated motion stream do show offset integration behavior across the entire stream. These results attest to the proposed linkage between subjective perception and integration behavior in the SQM.

Weaker groupitizing abilities in magnitude perception in dyscalculia

The mechanisms underlying simple arithmetic difficulties in dyscalculia are unknown. Evidence suggests deficiencies may arise from basic processes supporting magnitude perception and arithmetic proficiency. We focused on ‘groupitizing’, the ability to decompose and recompose quantities into a whole, examining whether adults with dyscalculia could benefit from visuospatial grouping cues when asked to estimate the quantity of a given set of different number ranges. Results showed adults with dyscalculia tended to focus on individual items rather than grouping them, resulting in low estimation abilities in both small and large quantity ranges. However, the results highlight the importance of differentiating between large and small quantities in the groupitizing process: only where arithmetic was easy (small but not large quantities), were adults with dyscalculia able to demonstrate significant improvement when given grouping cues. Our findings suggest weaker groupitizing abilities play a significant role in magnitude perception and arithmetic proficiency levels in dyscalculia. Educational relevance statementPeople with dyscalculia have difficulties in basic arithmetic that impact their life in many ways, from simple tasks such as calculating change, to life-changing events such as entering higher education or making financial decisions. They use immature counting strategies to solve simple arithmetic questions despite otherwise intact intellectual abilities. The reasons for this are unclear. We argued there may be a link between simple arithmetic proficiency and quantity perception processes. Our study investigated the mechanisms underlying quantity perception that play a role in dyscalculia deficiencies. We focused on ‘groupitizing,’ a process that enables a person to estimate a given quantity more efficiently by recomposing subgroups rather than simply using a counting strategy. The findings suggested a disadvantage in basic groupitizing in people with dyscalculia. Moreover, counting procedures interfered with groupitizing processes and hindered arithmetic proficiency.

The interplay between spatial and non-spatial grouping cues over approximate number perception.

Humans and animals share the cognitive ability to quickly extract approximate number information from sets. Main psychophysical models suggest that visual approximate numerosity relies on segmented units, which can be affected by Gestalt rules. Indeed, arrays containing spatial grouping cues, such as connectedness, closure, and even symmetry, are underestimated compared to ungrouped arrays with equal low-level features. Recent evidence suggests that non-spatial cues, such as color-similarity, also trigger numerosity underestimation. However, in natural vision, several grouping cues may coexist in the scene. Notably, conjunction of grouping cues (color and closure) reduces perceived numerosity following an additive rule. To test whether the conjunction-effect holds for other Gestalt cues, we investigated the effect of connectedness and symmetry over numerosity perception both in isolation and, critically, in conjunction with luminance similarity. Participants performed a comparison-task between a reference and a test stimulus varying in numerosity. In Experiment 1, test stimuli contained two isolated groupings (connectedness or luminance), a conjunction (connectedness and luminance), and a neutral condition (no groupings). Results show that point of subjective equality was higher in both isolated grouping conditions compared to the neutral condition. Furthermore, in the conjunction condition, the biases from isolated grouping cues added linearly, resulting in a numerosity underestimation equal to the sum of the isolated biases. In Experiment 2 we found that conjunction of symmetry and luminance followed the same additive rule. These findings strongly suggest that both spatial and non-spatial isolated cues affect numerosity perception. Crucially, we show that their conjunction effect extends to symmetry and connectedness.

Age-related disgust responses to signs of disease

ABSTRACT Previous studies found similarities in adults’ disgust responses to benign (e.g. obesity) and actual disease signs (e.g. influenza). However, limited research has compared visual (i.e. benign and actual) to cognitive (i.e. disease label) disease cues in different age groups. The current study investigated disgust responses across middle childhood (7–9 years), late childhood (10–12 years), adolescence (13–17 years), and adulthood (18+ years). Participants viewed individuals representing a benign visual disease (obese), sick-looking (staphylococcus), sick-label (cold/flu), and healthy condition. Disgust-related outcomes were: (1) avoidance, or contact level with apparel the individual was said to have worn, (2) disgust facial reactions, and (3) a combination of (1) and (2). Avoidance was greater for the sick-looking and sick-label than the healthy and obese conditions. For facial reaction and combination outcomes, middle childhood participants responded with greater disgust to the sick-looking than the healthy condition, while late childhood participants expressed stronger disgust towards the sick-looking and obese conditions than the healthy condition. Adolescents and adults exhibited stronger disgust towards sick-label and sick-looking than obese and healthy conditions. Results suggest visual cues are central to children’s disgust responses whereas adolescents and adult responses considered cognitive cues.

No effect of spatial congruence on rapid temporal recalibration to audiovisual asynchrony.

The brain integrates multisensory information to construct coherent perceptual representations based on spatial and temporal congruence. Intriguingly, multisensory timing perception can be flexibly calibrated. Repeated exposure to audiovisual asynchrony induces shifts in subjective simultaneity (temporal recalibration). Spatial congruence is known to serve as a grouping cue for recalibration when the audiovisual temporal relationship is ambiguous during exposure. A single exposure to audiovisual asynchrony can also trigger temporal recalibration (rapid recalibration). However, it has been suggested that the underlying mechanisms of these temporal recalibrations differ. Here, we examined whether spatial congruence can be a grouping cue for rapid recalibration when audiovisual pairs are not defined by temporal relationships. Participants made a simultaneity judgment for a pair of audiovisual stimuli after adapting three consecutive stimuli once in a "light-sound-light" or "sound-light-sound" order with an equal temporal interval. The spatial positions of the adapting stimuli were manipulated as an audiovisual pair from the same position (e.g., left) and the remaining stimulus from another position (e.g., right). In three experiments, the spatial congruence of the audiovisual adapting stimuli did not show a modulatory effect, while we replicated the rapid recalibration effects. Rather, rapid recalibration occurred according to the temporal order of the first light and sound. Our findings suggest that, in contrast to temporal recalibration with repeated exposure, the perceptual systems underlying rapid recalibration simply combine individual visual and auditory inputs based on the order in which they arrive.

Comparing the influence of auditory streaming cues on binaural pitch fusion in normal-hearing and hearing-impaired listeners

Binaural pitch fusion occurs when dichotic signals eliciting a different pitch are perceived as one sound. Previously, we investigated the effects of auditory streaming cues on binaural fusion using a modification of the ABA streaming paradigm. A dichotic stimulus (fixed tone at frequency fref in the reference ear and variable frequency in the contralateral ear) was presented at alternating intervals with up to 3 “capture” tones at fref. Participants reported whether they perceived galloping or two streams. Binaural fusion frequency range decreased with the number of capture tones and longer inter-stimulus intervals (ISIs), suggesting competition of sequential grouping with capture tones versus simultaneous grouping (fusion) with the dichotic tone. In the present study, we compared the effects in NH and hearing-impaired (HI) listeners. Preliminary data from 13 NH and 5 HI listeners suggest greater reductions in fusion range with number of capture tones and with longer ISI in HI listeners, especially in listeners with broad binaural fusion. These findings indicate that auditory grouping cues can reduce binaural fusion in both NH and HI listeners. Funded by NIH/NIDCD R01DC013307.

Additivity of grouping by proximity and luminance similarity is dependent on relative grouping strength: An analysis of individual differences in grouping sensitivity.

It has previously been shown that grouping by proximity is well described by a linear function relating the perceived orientation of a dot lattice to the ratio of the distances between the dots in the different orientations. Similarly, luminance influences how observers perceptually group stimuli. Using the dot lattice paradigm, it has been shown that proximity and luminance similarity interact additively, which means that their effects can be summed to predict an observers' percept. In this study, we revisit the additive interplay between proximity and luminance similarity and weask whether this pattern might be the result of inappropriately averaging different types of observers or the imbalance between the strength of proximity grouping and luminance similarity grouping. To address these questions, we first ran a replication of the original study reporting the additive interplay between proximity and luminance similarity. Our results showed a convincing replication at the aggregate and individual level. However, at the individual level, all observers showed grouping by proximity whereas some observers did not show grouping by luminance similarity. In response, we ran a second experiment with enlarged luminance differences to reinforce the strength of grouping by luminance similarity and balance the strengthof the two grouping cues. Interestingly, in this second experiment, additivity was not observedbut instead a significant interaction was obtained. This disparity suggests that the additivity orinteraction between two grouping cues in a visual stimulus is not a general rule of perceptual grouping but a consequence of relative grouping strength.

The mid-level vision toolbox for computing structural properties of real-world images

Mid-level vision is the intermediate visual processing stage for generating representations of shapes and partial geometries of objects. Our mechanistic understanding of these operations is limited, in part, by a lack of computational tools for analyzing image properties at these levels of representation. We introduce the Mid-Level Vision (MLV) Toolbox, an open-source software that automatically processes low- and mid-level contour features and perceptual grouping cues from real-world images. The MLV toolbox takes vectorized line drawings of scenes as input and extracts structural contour properties. We also include tools for contour detection and tracing for the automatic generation of vectorized line drawings from photographs. Various statistical properties of the contours are computed: the distributions of orientations, contour curvature, and contour lengths, as well as counts and types of contour junctions. The toolbox includes an efficient algorithm for computing the medial axis transform of contour drawings and photographs. Based on the medial axis transform, we compute several scores for local mirror symmetry, local parallelism, and local contour separation. All properties are summarized in histograms that can serve as input into statistical models to relate image properties to human behavioral measures, such as esthetic pleasure, memorability, affective processing, and scene categorization. In addition to measuring contour properties, we include functions for manipulating drawings by separating contours according to their statistical properties, randomly shifting contours, or rotating drawings behind a circular aperture. Finally, the MLV Toolbox offers visualization functions for contour orientations, lengths, curvature, junctions, and medial axis properties on computer-generated and artist-generated line drawings. We include artist-generated vectorized drawings of the Toronto Scenes image set, the International Affective Picture System, and the Snodgrass and Vanderwart object images, as well as automatically traced vectorized drawings of set architectural scenes and the Open Affective Standardized Image Set (OASIS).

Fundamental units of numerosity estimation

Humans can approximately enumerate a large number of objects at a single glance. While several mechanisms have been proposed to account for this ability, the fundamental units over which they operate remain unclear. Previous studies have argued that estimation mechanisms act only on topologically distinct units or on units formed by spatial grouping cues such as proximity and connectivity, but not on units grouped by similarity. Over four experiments, we tested this claim by systematically assessing and demonstrating that similarity grouping leads to underestimation, just as spatial grouping does. Ungrouped objects with the same low-level properties as grouped objects did not cause underestimation. Further, the underestimation caused by spatial and similarity grouping was additive, suggesting that these grouping processes operate independently. These findings argue against the proposal that estimation mechanisms operate solely on topological units. Instead, we conclude that estimation processes act on representations constructed after Gestalt grouping principles, whether similarity based or spatial, have organised incoming visual input.

A Visual Target Representation using Saliency Detection Approach

The task of saliency detection is to identify the most important and informative part of a scene. Saliency detection is broadly applied to numerous vision problems, including image segmentation, object recognition, image compression, content-based image retrieval, and moving object detection. Existing saliency detection methods suffer a low accuracy rate because of missing components of saliency regions. This study proposes a visual saliency detection method for the target representation to represent targets more accurately. The proposed method consists of five modules. In the first module, the salient region is extracted through manifold ranking on a graph, which incorporates local grouping cues and boundary priors. Secondly, using a region of interest (ROI) algorithm and the subtraction of the salient region from the original image, other parts of the image, either related or nonrelated to the interested target, are segmented. Lastly, those related and non-related regions are classified and distinguished using our proposed algorithm. Experimental result shows that proposed salient region accurately represent the interested target which can be used for object detection and tracking applications.

Groupitizing reflects conceptual developments in math cognition and inequities in math achievement from childhood through adolescence.

Understanding the cognitive processes central to mathematical development is crucial to addressing systemic inequities in math achievement. We investigate the "Groupitizing" ability in 1209 third to eighth graders (mean age at first timepoint=10.48, 586 girls, 39.16% Asian, 28.88% Hispanic/Latino, 18.51% White), a process that captures the ability to use grouping cues to access the exact value of a set. Groupitizing improves each year from late childhood to early adolescence (d=3.29), is a central predictor of math achievement (beta weight=.30), is linked to conceptual processes in mathematics (minimum d=0.69), and helps explain the dynamic between the ongoing development of non-symbolic number concepts, systemic educational inequities in school associated with SES, and mathematics achievement (minimum beta weight=.11) in ways that explicit symbolic measures may miss.

The competition between grouping cues can be resolved under inattention.

We investigated whether attention is required for the resolution of the competition between conflicting grouping cues. Participants performed a demanding change-detection task on a small matrix presented on a backdrop composed of two organizations that could change or stay the same between two consecutive displays independently from changes in the target. We hypothesized that if the competition between the backdrop organizations can be resolved without attention, congruency effects should emerge between changes in the target and changes in the organization that won the competition, but not for the other organization. Three trial types were examined: no-conflict trials, where the two grouping cues formed the same organization (e.g., columns by proximity and by color similarity); conflict trials, where the two cues formed conflicting organizations (e.g., columns by proximity and rows by color similarity); and mixed trials, where one backdrop display depicted no conflict while the other depicted conflicting organizations. Congruency effects were elicited by one organization (Experiment 1-proximity, Experiment 2-common region) but not by the other (color similarity, Experiments 1-2), in the no-conflict and mixed trials, suggesting that if one display in a trial was well organized it facilitated the resolution of the competition in the other display. However, when resolving the competition was required for both displays within a trial, it was not accomplished without attention. Thus, this study shows novel results revealing some of the conditions in which the competition between grouping cues can be resolved without attention.

Investigating the influence of auditory streaming cues on binaural pitch fusion

Binaural pitch fusion occurs when dichotic signals eliciting a different pitch are perceived as one sound. Previously, Oh et al. (ASA 2018) investigated the effects of auditory streaming cues on binaural fusion using a modification of the ABA streaming paradigm. A dichotic stimulus (fixed tone at frequency fref in the reference ear and variable frequency in the contralateral ear) was presented at alternating intervals with a “capture” tone at fref. Binaural fusion frequency range decreased, suggesting competition of the capture with the variable frequency tone for fusion. The present study added more capture tones, allowing for a galloping percept, and varied the inter-stimulus interval (ISI), both hypothesized to decrease binaural fusion by increasing salience of the capture tone. The dichotic stimulus was presented alternating with two or three repetitions of the capture tone at fref for triplet and quadruplet paradigms, respectively. ISIs of 40 or 80ms were used. Participants reported whether they perceived galloping or two streams. Preliminary data from 5 normal-hearing listeners suggest reductions in binaural fusion range with the triplet and quadruplet paradigms, and longer ISI, compared to the original paradigm. These findings indicate that auditory grouping cues may potentially reduce binaural fusion. [Research funded by NIH/NIDCD R01DC013307.]

A Taxonomy of Orchestral Grouping Effects Derived from Principles of Auditory Perception

The study of timbre and orchestration in symphonic music research is underexplored, and few theories attempt to explain strategies for combining and contrasting instruments and the resulting perception of orchestral structures and textures. An analysis of orchestration treatises and musical scores reveals an implicit understanding of auditory grouping principles by which many orchestration techniques give rise to predictable perceptual effects. We present a novel theory formalized in a taxonomy of devices related to auditory grouping principles that appear frequently in Western orchestration practices from a range of historical epochs. We develop three classes of orchestration analysis categories: concurrent grouping cues result in blended combinations of instruments; sequential grouping cues result in melodic lines, the integration of surface textures, and the segregation of melodies or stratified (foreground and background) layers based on acoustic (dis)similarities; segmental grouping cues contrast sequentially presented blocks of materials and contribute to the creation of perceptual boundaries. The theory predicts orchestration-based perceptual structuring in music and may be applied to music of any style, culture, or genre.

Overt and implicit prosody contribute to neurophysiological responses previously attributed to grammatical processing

Recent neurophysiological research suggests that slow cortical activity tracks hierarchical syntactic structure during online sentence processing. Here we tested an alternative hypothesis: electrophysiological activity peaks at constituent phrase as well as sentence frequencies reflect cortical tracking of overt or covert (implicit) prosodic grouping. Participants listened to series of sentences presented in three conditions while electroencephalography (EEG) was recorded. First, prosodic cues in the sentence materials were neutralized. We found an EEG spectral power peak elicited at a frequency that only ‘tagged’ covert, implicit prosodic change, but not any major syntactic constituents. In the second condition, participants listened to a series of sentences with overt prosodic grouping cues that either aligned or misaligned with the syntactic phrasing in the sentences (initial overt prosody trials). Following each overt prosody trial, participants were presented with a second series of sentences lacking overt prosodic cues (instructed prosody trial) and were instructed to imagine the prosodic contour present in the previous, overt prosody trial. The EEG responses reflected an interactive relationship between syntactic processing and prosodic tracking at the frequencies of syntactic constituents (sentences and phrases): alignment of syntax and prosody boosted EEG responses, whereas their misalignment had an opposite effect. This was true for both overt and imagined prosody conditions. We conclude that processing of both overt and covert prosody is reflected in the frequency-tagged neural responses at sentence constituent frequencies. These findings need to be incorporated in any account that aims to identify neural markers reflecting syntactic processing.

Symmetry as a grouping cue for numerosity perception

To estimate the number of objects in an image, each element needs to be segregated as a single unit. Several principles guide the process of element identification, one of the strongest being symmetry. In the current study, we investigated how symmetry affects the ability to rapidly estimate the number of objects (numerosity). Participants judged the numerosity of asymmetric or symmetric arrays of various numerosities. The results show that the numerosity of symmetrical arrays was significantly underestimated at low numerosities, but the effect was greatly reduced at higher numerosities. Adding an additional axis of symmetry (double symmetry) further reduced perceived numerosity. The magnitude of the symmetry-driven underestimation was inversely correlated with autistic personality traits, consistent with previous work associating autistic traits with perceptual grouping. Overall, these results support the idea that perceived numerosity relies on object segmentation and grouping cues, with symmetry playing a key role.

Neural decoding dissociates perceptual grouping between proximity and similarity in visual perception.

Unlike single grouping principle, cognitive neural mechanism underlying the dissociation across two or more grouping principles is still unclear. In this study, a dimotif lattice paradigm that can adjust the strength of one grouping principle was used to inspect how, when, and where the processing of two grouping principles (proximity and similarity) were carried out in human brain. Our psychophysical findings demonstrated that similarity grouping effect was enhanced with reduced proximity effect when the grouping cues of proximity and similarity were presented simultaneously. Meanwhile, EEG decoding was performed to reveal the specific cognitive patterns involved in each principle by using time-resolved MVPA. More importantly, the onsets of dissociation between 2 grouping principles coincided within 3time windows: the early-stage proximity-defined local visual element arrangement in middle occipital cortex, the middle-stage processing for feature selection modulating low-level visual cortex such as inferior occipital cortex and fusiform cortex, and the high-level cognitive integration to make decisions for specific grouping preference in the parietal areas. In addition, it was discovered that the brain responses were highly correlated with behavioral grouping. Therefore, our study provides direct evidence for a link between the human perceptual space of grouping decision-making and neural space of brain activation patterns.

The complexity of simple counting: ERP findings reveal early perceptual and late numerical processes in different arrangements

The counting process can only be fully understood when taking into account the visual characteristics of the sets counted. Comparing behavioral data as well as event-related brain potentials (ERPs) evoked by different task-irrelevant arrangements of dots during an exact enumeration task, we aimed to investigate the effect of illusory contour detection on the counting process while other grouping cues like proximity were controlled and dot sparsity did not provide a cue to the numerosity of sets. Adult participants (N = 37) enumerated dots (8–12) in irregular and two different types of regular arrangements which differed in the shape of their illusory dot lattices. Enumeration speed was affected by both arrangement and magnitude. The type of arrangement influenced an early ERP negativity peaking at about 270 ms after stimulus onset, whereas numerosity only affected later ERP components (> 300 ms). We also observed that without perceptual cues, magnitude was constructed at a later stage of cognitive processing. We suggest that chunking is a prerequisite for more fluent counting which influences automatic processing (< 300 ms) during enumeration. We conclude that the procedure of exact enumeration depends on the interaction of several perceptual and numerical processes that are influenced by magnitude and arrangement.

The time course of holistic processing is similar for face and non-face Gestalt stimuli.

There is evidence that holistic processing of faces and other stimuli rich in Gestalt perceptual grouping cues recruit overlapping mechanisms at early processing stages, but not at later stages where faces and objects of expertise likely overlap. This has led to suggestions of dual pathways supporting holistic processing; an early stimulus-based pathway (supporting processing of stimuli rich in perceptual grouping cues) and an experience-based pathway (supporting processing of object of expertise), with both pathways supporting face processing. Holistic processing markers are present when upright faces are presented for as little as 50-ms. If the overlap between holistic processing of faces and stimuli rich in grouping cues occurs early in processing, markers of holistic processing for these Gestalt stimuli should be present as early as those for faces. In Experiment 1, we investigate the time-course of the emergence of holistic processing markers for face and non-face Gestalt stimuli. The emergence of these markers for faces and the Gestalt stimuli was strikingly similar; both emerged with masked presentations as little as 50-ms. In Experiment 2, where the stimulus presentation was not masked, thus the presentation duration, but not the post-presentation perceptual processing, was constrained, patterns of holistic processing for these stimuli still did not diverge. These findings are consistent with an early, and possibly extended, temporal locus for the overlap in the holistic processing of faces and non-face stimuli rich in grouping cues.

The effect of target and interferer frequency on across-frequency binaural interference of interaural-level-difference sensitivity.

Across-frequency binaural interference occurs when the sensitivity to changes in interaural differences in a target sound is decreased by a spectrally remote diotic interfering sound. For interaural time differences (ITDs), low-frequency (e.g., 0.5 kHz) interferers cause more interference on high-frequency (e.g., 4 kHz) targets than vice versa. For interaural level differences (ILDs), however, it is unclear if a frequency dependence exists. Therefore, ILD discrimination thresholds and across-frequency binaural interference were measured for target and interferer frequencies between 0.5 and 8 kHz (for tones) or 12 kHz (for narrowband noises). For tones, 8-kHz targets experienced the least interference and 8-kHz interferers produced the most interference, suggesting that higher-frequency ILDs are a more heavily weighted localization cue than lower-frequency ILDs. For narrowband noises, the frequency-dependent interference patterns increased in complexity in comparison to tones. Low-frequency ITD dominance (from randomly varying onset ITDs) and grouping cues (e.g., envelope modulations) might explain some of the complexity in the interference patterns for the noises. These data contribute to a better understanding of across-frequency ILD processing, which remains poorly understood.