The factorial structure of individual differences in visual perception

Individual differences in visual search: A systematic review of the link between visual search performance and traits or abilities

Visual search (VS) comprises a class of tasks that we typically perform several times during a day and requires intentionally scanning (with or without moving the eyes) the environment for a specific target (be it an object or a feature) among distractor stimuli. Experimental research in lab-based or real-world settings has offered insight into its underlying neurocognitive mechanisms from a nomothetic point of view. A lesser-known but rapidly growing body of quasi-experimental and correlational research has explored the link between individual differences and VS performance. This combines different research traditions and covers a wide range of individual differences in studies deploying a vast array of VS tasks. As such, it is a challenge to determine whether any associations highlighted in single studies are robust when considering the wider literature. However, clarifying such relationships systematically and comprehensively would help build more accurate models of VS, and it would highlight promising directions for future research. This systematic review provides an up to date and comprehensive synthesis of the existing literature investigating associations between common indices of performance in VS tasks and measures of individual differences mapped onto four categories of cognitive abilities (short-term working memory, fluid reasoning, visual processing and processing speed) and seven categories of traits (Big Five traits, trait anxiety and autistic traits). Consistent associations for both traits (in particular, conscientiousness, autistic traits and trait anxiety - the latter limited to emotional stimuli) and cognitive abilities (particularly visual processing) were identified. Overall, however, informativeness of future studies would benefit from checking and reporting the reliability of all measurement tools, applying multiplicity correction, using complementary techniques, study preregistration and testing why, rather than only if, a robust relation between certain individual differences and VS performance exists.

Identification of breadfruit (Artocarpus altilis) and South American crops introduced during early settlement of Rapa Nui (Easter Island), as revealed through starch analysis

Starch residue analysis was carried out on stone tools recovered from the bottom layer of the Anakena site on Rapa Nui (Easter Island). These deposits have been dated to AD 1000-1300 AD and so far, represent the earliest evidence of human settlement on this island. Twenty obsidian tools were analyzed. Analysis of 46 starch grains recovered from 20 obsidian tools from the earliest dated level of the Anakena site on Rapa Nui provides direct evidence for translocation of traditional crop plants at initial stages of the colonization of this island. The analysis of starch grains was based mainly on statistical methods for species identification but was complemented by visual inspection in some cases. Our results identify taxons previously unknown to have been cultivated on the island, such as breadfruit (Artocarpus altilis), Zingiber officinale (ginger), and starch grains of the Spondias dulcis and Inocarpus fagifer tropical trees. Additionally, starch grains of Colocasia esculenta (taro) and Dioscorea sp. (yam), both common species in Pacific agriculture, were identified. Furthermore, the presence of four American taxa Ipomoea batatas (sweet potato), Canna sp. (achira), Manihot esculenta (manioc), and Xanthosoma sp., was detected. The occurrence of Canna sp., M. esculenta, and Xanthosoma sp. starch grains suggests the translocation of previously not described South American cultivars into the Pacific. The detection of I. batatas from this site in Rapa Nui constitutes the earliest record of this cultigen in the Pacific. Our study provides direct evidence for translocation of a set of traditional Polynesian and South American crop plants at the initial stages of colonization in Rapa Nui.

Influences of local and global context on local orientation perception

Visual context modulates perception of local orientation attributes. These spatially very localised effects are considered to correspond to specific excitatory-inhibitory connectivity patterns of early visual areas as V1, creating perceptual tilt repulsion and attraction effects. Here, orientation misperception of small Gabor stimuli was used as a probe of this computational structure by sampling a large spatio-orientation space to reveal expected asymmetries due to the underlying neuronal processing. Surprisingly, the results showed a regular iso-orientation pattern of nearby location effects whose reference point was globally modulated by the spatial structure, without any complex interactions between local positions and orientation. This pattern of results was confirmed by the two perceptual parameters of bias and discrimination ability. Furthermore, the response times to stimulus configuration displayed variations that further provided evidence of how multiple early visual stages affect perception of simple stimuli.

Exploring the extent to which shared mechanisms contribute to motion-position illusions

Motion-position illusions (MPIs) are visual motion illusions in which motion signals bias the perceived position of an object. Due to phenomenological similarities between these illusions, previous research has assumed that some are caused by common mechanisms. However, this assumption has yet to be directly tested. This study investigates this assumption by exploiting between-participant variations in illusion magnitude. During two sessions, 106 participants viewed the flash-lag effect, luminance flash-lag effect, Fröhlich effect, flash-drag effect, flash-grab effect, motion-induced position shift, twinkle-goes effect, and the flash-jump effect. For each effect, the magnitude of the illusion was reliable within participants, strongly correlating between sessions. When the pairwise correlations of averaged illusions magnitudes were explored, two clusters of statistically significant positively correlated illusions were identified. The first cluster comprised the flash-grab effect, motion-induced position shift, and twinkle-goes effect. The second cluster comprised the Fröhlich and flash-drag effect. The fact that within each of these two clusters, individual differences in illusion magnitude were correlated suggests that these clusters may reflect shared underlying mechanisms. An exploratory factor analysis provided additional evidence that these correlated clusters shared an underlying factor, with each cluster loading onto their own factor. Overall, our results reveal that, contrary to the prevailing perspective in the literature, while some motion-position illusions share processes, most of these illusions are unlikely to reflect any shared processes, instead implicating unique mechanisms.

Exploring the role of structuralist methodology in the neuroscience of consciousness: a defense and analysis

Traditional contrastive analysis has been the foundation of consciousness science, but its limitations due to the lack of a reliable method for measuring states of consciousness have prompted the exploration of alternative approaches. Structuralist theories have gained attention as an alternative that focuses on the structural properties of phenomenal experience and seeks to identify their neural encoding via structural similarities between quality spaces and neural state spaces. However, the intertwining of philosophical assumptions about structuralism and structuralist methodology may pose a challenge to those who are skeptical of the former. In this paper, I offer an analysis and defense of structuralism as a methodological approach in consciousness science, which is partly independent of structuralist assumptions on the nature of consciousness. By doing so, I aim to make structuralist methodology more accessible to a broader scientific and philosophical audience. I situate methodological structuralism in the context of questions concerning mental representation, psychophysical measurement, holism, and functional relevance of neural processes. At last, I analyze the relationship between the structural approach and the distinction between conscious and unconscious states.

No Common Factor Underlying Decline of Visual Abilities in Mild Cognitive Impairment

INTRODUCTION

Recent work has shown an association between cognitive and visual impairments and two main theories were advanced, namely the sensory deprivation and the common cause theories. Most studies considered only basic visual functions such as visual acuity or visual field size and evaluated the association with dementia.

OBJECTIVES

To reconcile between these theories and to test the link between visual and cognitive decline in mildly cognitive impaired people.

METHODS

We employed a battery of 19 visual tasks on 39 older adults with mild cognitive impairment and 91 without any evidence of cognitive decline, as measured by the Montreal Cognitive Assessment.

RESULTS

Our results show a strong association between visual impairment and mild cognitive impairment. In agreement with previous results with younger and healthy older adults, we found also only weak correlations between most tests in older adults with mild cognitive impairment.

CONCLUSION

Our results suggest that visual and cognitive abilities decline simultaneously, but they do so independently across visual and cognitive functions and across participants.

Estimation error of the body surface area in psoriasis: A comparative study of physician and computer-assisted image analysis (Image J)

BACKGROUND

Assessing the area involved, i.e., the body surface area (BSA), is essential in diagnosing the disease severity of psoriasis. However, the BSA estimated by physicians tends to be over-estimated and has shown high inter- and intra-rater variabilities. Furthermore, no reports suggesting the cause and clinical significance of overestimating the BSA results exist in psoriasis patients.

OBJECTIVES

We aimed to investigate the errors in estimating the BSA affected by psoriasis by comparing the physicians' results with those of computer-assisted image analysis (CAIA) and provide suggestions regarding the clinical implications of such errors.

METHODS

Using 43 images, 36 physicians visually estimated the BSA of psoriasis. Subsequently, the images were evaluated using CAIA (Image J). The BSA values determined by the physicians and CAIA were compared and matched. The BSA percentage was also graded from 0 to 6: no lesion (0), 1-9% (1), 10-29% (2), 30-49% (3), 50-69% (4), 70-89% (5), and 90-100% (6). Each grade range was divided, with the bottom and top 50% defined as the "first half" and "second half," respectively.

RESULTS

The average proportion of correct assessments by physicians was 49.4%. Physicians tended to overestimate the area involved by psoriatic lesions by 8.76%±8.82% compared to CAIA. The largest estimation error (proportion incorrect: 75.7%) was observed in Grade 3. Estimations located in the "second half" of the range demonstrated a higher proportion of inaccuracies compared to those in the "first half." An overestimating error occurred in certain morphological characteristics of the psoriatic lesions.

CONCLUSIONS

Inaccuracy of BSA estimation by physicians may be related that information from the human eye is perceived to be exaggerated compared to the actual size. Further research of using artificial intelligence (AI) technology is needed to reduce quantification error and develop an ideal BSA assessment system. Additionally, education and training are needed for physicians to accurately measure the BSA.

How do visual skills relate to action video game performance?

It has been claimed that video gamers possess increased perceptual and cognitive skills compared to non-video gamers. Here, we examined to which extent gaming performance in CS:GO (Counter-Strike: Global Offensive) correlates with visual performance. We tested 94 players ranging from beginners to experts with a battery of visual paradigms, such as visual acuity and contrast detection. In addition, we assessed performance in specific gaming skills, such as shooting and tracking, and administered personality traits. All measures together explained about 70% of the variance of the players’ rank. In particular, regression models showed that a few visual abilities, such as visual acuity in the periphery and the susceptibility to the Honeycomb illusion, were strongly associated with the players’ rank. Although the causality of the effect remains unknown, our results show that high-rank players perform better in certain visual skills compared to low-rank players.

Individual differences in the perception of visual illusions are stable across eyes, time, and measurement methods

Vision scientists have tried to classify illusions for more than a century. For example, some studies suggested that there is a unique common factor for all visual illusions. Other studies proposed that there are several subclasses of illusions, such as illusions of linear extent or distortions. We previously observed strong within-illusion correlations but only weak between-illusion correlations, arguing in favor of an even higher multifactorial space with-more or less-each illusion making up its own factor. These mixed results are surprising. Here, we examined to what extent individual differences in the perception of visual illusions are stable across eyes, time, and measurement methods. First, we did not find any significant differences in the magnitudes of the seven illusions tested with monocular or binocular viewing conditions. In addition, illusion magnitudes were not significantly predicted by visual acuity. Second, we observed stable individual differences over time. Last, we compared two illusion measurements, namely an adjustment procedure and a method of constant stimuli, which both led to similar individual differences. Hence, it is unlikely that the individual differences in the perception of visual illusions arise from instability across eyes, time, and measurement methods.

Feature-specificity in visual statistical summary processing

Visual statistical summary processing enables people to extract the average feature of a set of items rapidly and accurately. Previous studies have demonstrated independent mechanisms for summarizing low (e.g. color, orientation) and high-level (facial identity, emotion) visual information. However, no study to date has conclusively determined whether there are feature-specific summarization mechanisms for low-level features or whether there are low-level, feature agnostic summarization mechanisms. To address this issue, we asked participants to report either the average orientation or the average size from a set of lines where both features varied. Participants completed these tasks either in single-task or mixed-task conditions; in the latter, successful performance required extraction of both summaries concurrently. If there were feature-specific summarization mechanisms that could operate in parallel, then errors in mean size and mean orientation tasks should be independent, in both single and mixed task conditions. On the other hand, a central domain-general mechanism for low-level summarization would imply a correlation between errors for both features and greater error in the mixed than single task trials. In Experiment 1, we found that there was no correlation between the mean size and mean orientation errors and performance was similar across single and mixed-task conditions, suggesting that there may be independent summarization mechanisms for size and orientation features. To further test the feature-specificity account, in Experiment 2 and 3 (with mask), we manipulated the display duration to determine whether there were any differences in the summarization of earlier (orientation) vs. later (size) features. While these experiments replicated the pattern of results observed in Experiment 1, at shorter display durations, no differences emerged across features. We argue that our data is consistent with independent, multi-level feature-specific statistical summary mechanisms for low-level visual features.

When illusions merge

We recently found only weak correlations between the susceptibility to various visual illusions. However, we observed strong correlations among different variants of an illusion, suggesting that the visual space of illusions includes several illusion-specific factors. Here, we specifically examined how factors for the vertical-horizontal, Müller-Lyer, and Ponzo illusions relate to each other. We measured the susceptibility to each illusion separately and to combinations of two illusions, which we refer to as a merged illusion; for example, we tested the Müller-Lyer illusion and the vertical-horizontal illusion, as well as a merged version of both illusions. We used an adjustment procedure in two experiments with 306 and 98 participants, respectively. Using path analyses, correlations, and exploratory factor analyses, we found that the susceptibility to a merged illusion is well predicted from the susceptibilities to the individual illusions. We suggest that there are illusion-specific factors that, by independent combinations, represent the whole visual structure underlying illusions.

Individual differences in the Müller-Lyer and Ponzo illusions are stable across different contexts

Vision scientists have attempted to classify visual illusions according to certain aspects, such as brightness or spatial features. For example, Piaget proposed that visual illusion magnitudes either decrease or increase with age. Subsequently, it was suggested that illusions are segregated according to their context: real-world contexts enhance and abstract contexts inhibit illusion magnitudes with age. We tested the effects of context on the Müller-Lyer and Ponzo illusions with a standard condition (no additional context), a line-drawing perspective condition, and a real-world perspective condition. A mixed-effects model analysis, based on data from 76 observers with ages ranging from 6 to 66 years, did not reveal any significant interaction between context and age. Although we found strong intra-illusion correlations for both illusions, we found only weak inter-illusion correlations, suggesting that the structure underlying these two spatial illusions includes several specific factors.