Gauging response time distributions to examine the effect of facial expression inversion.

Introduction: We used images of facial expressions (FEs) of emotion in a speeded Same/Different task to examine (i) distributional characteristics of response times (RTs) in relation to inter-stimulus similarity and (ii) the impact of inversion on FE processing. Methods: Stimuli were seven emotion prototypes, posed by one male and one female, and eight intermediate morphs. Image pairs (N = 225) were presented for 500 ms, upright or inverted, in a block design, each 100 times. Results: For both upright and inverted FEs, RTs were a non-monotonic function: median values were longest for stimulus pairs of intermediate similarity, decreasing for both more-dissimilar and more-similar pairs. RTs of "Same" and "Different" judgments followed ex-Gaussian distributions. The non-monotonicity is interpreted within a dual-process decision model framework as reflecting the infrequency of identical pairs, shifting the balance between the Same and Different processes. The effect of stimulus inversion was gauged by comparing RT-based multidimensional scaling solutions for the two presentation modes. Solutions for upright and inverted FEs showed little difference, with both displaying some evidence of categorical perception. The same features appeared in hierarchical clustering solutions. Discussion: This outcome replicates and reinforces the solutions derived from accuracy of "Different" responses reported in our earlier companion paper. We attribute this lack of inversion effect to the brief exposure time, allowing low-level visual processing to dominate Same/Different decisions while elevating early featural analysis, which is insensitive to face orientation but enables initial positive/negative valence categorization of FEs.

Florence "blues" are clothed in triple basic terms.

Psycholinguistic studies provide evidence that Italian has more than one basic color term (BCT) for "blue": consensually, blu denotes "dark blue," while "light-and-medium blue," with diatopic variation, is termed either azzurro or celeste. For Tuscan speakers (predominantly from Florence), the BLUE area is argued to linguistically differentiate between azzurro "medium blue" and celeste "light blue." We scrutinized "basicness" of the three terms. Participants (N = 31; university students/graduates born in Tuscany) named each chip of eight Munsell charts encompassing the BLUE area (5BG-5PB; N = 237) using an unconstrained color-naming method. They then indicated the "best exemplar" (focal color) of blu, azzurro and celeste. We found that frequencies of the three terms and of term derivatives were comparable. Referential meaning of blu, azzurro, and celeste was estimated in CIELAB space as L*a*b*-coordinates of the mean of focal colors and as "modal" categories, that is, dispersion around the mean. The three "blue" terms were distinct on both measures and separated along all three CIELAB dimensions but predominantly along the L*-dimension. Our results provide evidence that Tuscan speakers require all three terms for naming the BLUE area, categorically refined along the lightness dimension. Furthermore, celeste appears to be a third BCT for "blue," along with commonly considered BCTs azzurro and blu. The "triple blues" as BCTs for Tuscan speakers are in contrast with outcomes of two "blue" basic terms estimated by using the same methodology in two other locations in Italy-azzurro and blu (Verona, Veneto region) or celeste and blu (Alghero, Sardinia).

Chromatic discrimination measures in mature observers depend on the response window.

Our past anecdotal evidence prompted that a longer response window (RW) in the Trivector test (Cambridge Colour Test) improved mature observers' estimates of chromatic discrimination. Here, we systematically explored whether RW variation affects chromatic discrimination thresholds measured by the length of Protan, Deutan and Tritan vectors. We employed the Trivector test with three RWs: 3 s, 5 s, and 8 s. Data of 30 healthy normal trichromats were stratified as age groups: 'young' (20-29 years), 'middle-aged' (31-48 years), and 'mature' (57-64 years). We found that for the 'young' and 'middle-aged', the thresholds were comparable at all tested RWs. However, the RW effect was apparent for the 'mature' observers: their Protan and Tritan thresholds decreased at 8-s RW compared to 3-s RW; moreover, their Tritan threshold decreased at 5-s RW compared to 3-s RW. Elevated discrimination thresholds at shorter RWs imply that for accurate performance, older observers require longer stimulus exposure and are indicative of ageing effects manifested by an increase in critical processing duration. Acknowledging low numbers in our 'middle-aged' and 'mature' samples, we consider our study as pilot. Nonetheless, our findings encourage us to advocate a RW extension in the Trivector protocol for testing mature observers, to ensure veridical measures of their chromatic discrimination by disentangling these from other ageing effects-slowing down of both motor responses and visual processing.

Color Affects Recognition of Emoticon Expressions.

In computer-mediated communication, emoticons are conventionally rendered in yellow. Previous studies demonstrated that colors evoke certain affective meanings, and face color modulates perceived emotion. We investigated whether color variation affects the recognition of emoticon expressions. Japanese participants were presented with emoticons depicting four basic emotions (Happy, Sad, Angry, Surprised) and a Neutral expression, each rendered in eight colors. Four conditions (E1-E4) were employed in the lab-based experiment; E5, with an additional participant sample, was an online replication of the critical E4. In E1, colored emoticons were categorized in a 5AFC task. In E2-E5, stimulus affective meaning was assessed using visual scales with anchors corresponding to each emotion. The conditions varied in stimulus arrays: E2: light gray emoticons; E3: colored circles; E4 and E5: colored emoticons. The affective meaning of Angry and Sad emoticons was found to be stronger when conferred in warm and cool colors, respectively, the pattern highly consistent between E4 and E5. The affective meaning of colored emoticons is regressed to that of achromatic expression counterparts and decontextualized color. The findings provide evidence that affective congruency of the emoticon expression and the color it is rendered in facilitates recognition of the depicted emotion, augmenting the conveyed emotional message.

Russian blues reveal the limits of language influencing colour discrimination.

Chromatic stimuli across a boundary of basic colour categories (BCCs; e.g. blue and green) are discriminated faster than colorimetrically equidistant colours within a given category. Russian has two BCCs for blue, sinij 'dark blue' and goluboj 'light blue'. These language-specific BCCs were reported to enable native Russian speakers to discriminate cross-boundary dark and light blues faster than English speakers (Winawer et al., 2007, PNAS, 4, 7780-7785). We re-evaluated this finding in two experiments that employed identical tasks as in the cited study. In Experiment 1, Russian and English speakers categorised colours as sinij/goluboj or dark blue/light blue respectively; this was followed by a colour discrimination task. In Experiment 2, Russian speakers initially performed the discrimination task on sinij/goluboj and goluboj/zelënyj 'green' sets. They then categorised these colours in three frequency contexts with each stimulus presented: (i) an equal number of times (unbiased); more frequent (ii) either sinij or goluboj; (iii) either goluboj or zelënyj. We observed a boundary response speed advantage for goluboj/zelënyj but not for sinij/goluboj. The frequency bias affected only the sinij/goluboj boundary such that in a lighter context, the boundary shifted towards lighter shades, and vice versa. Contrary to previous research, our results show that in Russian, stimulus discrimination at the lightness-defined blue BCC boundary is not reflected in processing speed. The sinij/goluboj boundary did have a sharper categorical transition than the dark blue/light blue boundary, but it was also affected by frequency and order biases, demonstrating that "Russian blues" are less well-structured than previously thought.

Art expertise in construing meaning of representational and abstract artworks.

Aesthetic appraisal of artwork can present the observer with visual problems to solve in the process of grasping its meaning and 'visual rightness' (i.e. "good" structure; Locher, 2003), with an elaboration on perceptual, semantic and affective dimensions (e.g. Markovic, 2011). Thus observer's expertise is a factor in aesthetic appraisal. To examine the influence of art training on the aesthetic response, and to clarify the nature of the Representational/Abstract distinction, 30 Experts and 33 Non-experts (Art and Psychology students, respectively) were asked to rate 24 paintings on six affective and affective-evaluative semantic differential scales. Stimuli were images of paintings from the period 1900-1935, 12 broadly Representational and 12 broadly Abstract. Relative to Non-experts, Experts rated Abstract artworks as more Interesting, Beautiful, Informative and Sophisticated, distinguishing them less markedly from Representational artworks. Aggregate Expert and Non-expert ratings, processed by factor analysis, resulted in a two-factor solution. The first factor, contrasting Abstract and Representational artworks, appeared more salient for Non-experts. The second factor, Cool-Warm, separating vibrantly-colored paintings from those with a blue-dominated/dull palette, was more salient for Experts. While Non-experts exaggerated differences between Abstract and Representational paintings, Experts appraised these two types of art similarly, attending more to artwork collative properties. We conclude that appreciation of art by Experts involves 'cognitive mastery' (Leder, Belke, Oeberst, & Augustin, 2004), i.e. more complex, cues-based visual schemata which equip them with more sophisticated strategies for analysing collative properties and semantics of an artwork while parsing 'visual rightness' to unfold its visual meaning.

A Relationship Between Visual Complexity and Aesthetic Appraisal of Car Front Images: An Eye-Tracker Study.

Image aesthetic pleasure (AP) is conjectured to be related to image visual complexity (VC). The aim of the present study was to investigate whether (a) two image attributes, AP and VC, are reflected in eye-movement parameters; and (b) subjective measures of AP and VC are related. Participants (N=26) explored car front images (M=50) while their eye movements were recorded. Following image exposure (10 seconds), its VC and AP were rated. Fixation count was found to positively correlate with the subjective VC and its objective proxy, JPEG compression size, suggesting that this eye-movement parameter can be considered an objective behavioral measure of VC. AP, in comparison, positively correlated with average dwelling time. Subjective measures of AP and VC were related too, following an inverted U-shape function best-fit by a quadratic equation. In addition, AP was found to be modulated by car prestige. Our findings reveal a close relationship between subjective and objective measures of complexity and aesthetic appraisal, which is interpreted within a prototype-based theory framework.

Variation of color discrimination across the life span.

The present study, an extension of Paramei [J. Opt. Soc. Am. A, 29, A290, 2012], provides normative data on chromatic discrimination, using the Cambridge Colour Test, for normal trichromats aged 10-88 years. Findings are in accord with a two-phase variation across the life span: chromatic sensitivity improves in adolescence, reaches a maximum around 30 years, and then undergoes a gradual decrease. Indicative parameters are Protan (P), Deutan (D), and Tritan (T) vector lengths and major axes and axis ratios of Ellipses. Trivector data are modeled as non-monotonic combinations of power functions, with goodness-of-fits R(P)2=0.23, R(D)2=0.23, and R(T)2=0.45. For advancing age, sensitivity decline in all chromatic systems was confirmed, though with a marked acceleration after 60 years (reflected by the power function exponent >1) and more pronounced for the tritan system.

Processing bimodal stimuli: integrality/separability of color and orientation.

We examined how two distinct stimulus features, orientation and color, interact as contributions to global stimulus dissimilarity. Five subjects rated dissimilarity between pairs of bars (N = 30) varying in color (four cardinal hues, plus white) and orientation (six angles at 30° intervals). An exploratory analysis with individual-differences multidimensional scaling (MDS) resulted in a 5D solution, with two dimensions required to accommodate the circular sequence of the angular attribute, and red-green, blue-yellow and achromatic axes for the color attribute. Weights of the orientation subspace relative to the color subspace varied among the subjects, from a 0.32:0.61 ratio to 0.53:0.44, emphasis shifting between color and orientation. In addition to Euclidean metric, we modeled the interaction of color and orientation using Minkowski power metrics across a range of Minkowski exponents p, including the city-block (p = 1), Euclidean (p = 2) and Dominance metric (p → ∞) as special cases. For averaged data, p ~ 1.3 provided the best fit, i.e., intermediate between separable and integral features. For individual subjects, however, the metric exponent varied significantly from p = 0.7 to p = 3.1, indicating a subject-specific rule for combining color and orientation, as in Tversky and Gati's variable-weights model. No relationship was apparent between dimensional weights and individual p exponents. Factors affecting dimensional integrality are discussed, including possible underlying neural mechanisms where the interaction of the low-level vision attributes orientation and color might shift between uncorrelated (p = 1) or correlated (p ≥ 2) forms.

Processing Facial Expressions of Emotion: Upright vs. Inverted Images.

We studied discrimination of briefly presented upright vs. inverted emotional facial expressions (FEs), hypothesizing that inversion would impair emotion decoding by disrupting holistic FE processing. Stimuli were photographs of seven emotion prototypes, of a male and female poser (Ekman and Friesen, 1976), and eight intermediate morphs in each set. Subjects made speeded Same/Different judgments of emotional content for all upright (U) or inverted (I) pairs of FEs, presented for 500 ms, 100 times each pair. Signal Detection Theory revealed the sensitivity measure d' to be slightly but significantly higher for the upright FEs. In further analysis using multidimensional scaling (MDS), percentages of Same judgments were taken as an index of pairwise perceptual similarity, separately for U and I presentation mode. The outcome was a 4D "emotion expression space," with FEs represented as points and the dimensions identified as Happy-Sad, Surprise/Fear, Disgust, and Anger. The solutions for U and I FEs were compared by means of cophenetic and canonical correlation, Procrustes analysis, and weighted-Euclidean analysis of individual differences. Differences in discrimination produced by inverting FE stimuli were found to be small and manifested as minor changes in the MDS structure or weights of the dimensions. Solutions differed substantially more between the two posers, however. Notably, for stimuli containing elements of Happiness (whether U or I), the MDS structure showed signs of implicit categorization, indicating that mouth curvature - the dominant feature conveying Happiness - is visually salient and receives early processing. The findings suggest that for briefly presented FEs, Same/Different decisions are dominated by low-level visual analysis of abstract patterns of lightness and edge filters, but also reflect emerging featural analysis. These analyses, insensitive to face orientation, enable initial positive/negative Valence categorization of FEs.

Color discrimination across four life decades assessed by the Cambridge Colour Test.

Color discrimination was estimated using the Cambridge Colour Test (CCT) in 160 normal trichromats of four life decades, 20-59 years of age. For each age cohort, medians and tolerance limits of the CCT parameters are tabulated. Compared across the age cohorts (Kruskal-Wallis test), the Trivector test showed increases in the three vectors, Protan, Deutan, and Tritan, with advancing age; the Ellipses test revealed significant elongation of the major axes of all three ellipses but no changes in either the axis ratio or the angle of the ellipse major axis. Multiple comparisons (Mann-Whitney test) between the cohorts of four age decades (20+,…,50+) revealed initial benign deterioration of color discrimination in the 40+ decade, as an incremental loss of discrimination along the Deutan axis (Trivector test), and in the 50+ decade, as an elongation of the major axes of all three ellipses (Ellipses test).

Color vision impairment in type 2 diabetes assessed by the D-15d test and the Cambridge Colour Test.

Color vision impairment emerges at early stages of diabetes mellitus type 2 (DM2) and may precede diabetic retinopathy or the appearance of vascular alterations in the retina. The aim of the present study was to compare the evaluation of the color vision with two different tests - the Lanthony desaturated D-15d test (a traditional color arrangement test), and the Cambridge Colour Test (CCT) (a computerized color discrimination test) - in patients diagnosed with DM2 without clinical signs of diabetic retinopathy (DR), and in sex- and age-matched control groups. Both color tests revealed statistically significant differences between the controls and the worst eyes of the DM2 patients. In addition, the degree of color vision impairment diagnosed by both tests correlated with the disease duration. The D-15d outcomes indicated solely tritan losses. In comparison, CCT outcomes revealed diffuse losses in color discrimination: 13.3% for best eyes and 29% for worst eyes. In addition, elevation of tritan thresholds in the DM2 patients, as detected by the Trivector subtest of the CCT, was found to correlate with the level of glycated hemoglobin. Outcomes of both tests confirm that subclinical losses of color vision are present in DM2 patients at an early stage of the disease, prior to signs of retinopathy. Considering the advantages of the CCT test compared to the D-15d test, further studies should attempt to verify and/or improve the efficiency of the CCT test.

Color-space distortions following long-term occupational exposure to mercury vapor.

Color vision was examined in subjects with long-term occupational exposure to mercury (Hg) vapor. The color vision impairment was assessed by employing a quantitative measure of distortion of individual and group perceptual color spaces. Hg subjects (n = 18; 42.1 ± 6.5 years old; exposure time = 10.4 ± 5.0 years; time away from the exposure source = 6.8 ± 4.6 years) and controls (n = 18; 46.1 ± 8.4 years old) were examined using two arrangement tests, D-15 and D-15d, in the traditional way, and also in a triadic procedure. From each subject's 'odd-one-out' choices, matrices of inter-cap subjective dissimilarities were derived and processed by non-metric multidimensional scaling (MDS). D-15d results differed significantly between the Hg-group and the control group (p < 0.05), with the impairment predominantly along the tritan axis. 2D perceptual color spaces, individual and group, were reconstructed, with the dimensions interpreted as the red-green (RG) and the blue-yellow (BY) systems. When color configurations from the Hg-group were compared to those of the controls, they presented more fluctuations along both chromatic dimensions, indicating a statistically significant difference along the BY axis. In conclusion, the present findings confirm that color vision impairments persist in subjects that have received long-term occupational exposure to Hg-vapor although, at the time of testing, they were presenting mean urinary concentration within the normal range for non-exposed individuals. Considering the advantages of the triadic procedure in clinical evaluation of acquired color vision deficiencies, further studies should attempt to verify and/or improve its efficacy.

Impairments of Gestalt perception in the intact hemifield of hemianopic patients are reflected in gamma-band EEG activity.

Gamma-band responses (GBRs) are associated with Gestalt perception processes. In the present EEG study, we investigated the effects of perceptual grouping on the visual GBR in the perimetrically intact visual field of patients with homonymous hemianopia and compared them to healthy participants. All observers were presented either random arrays of Gabor elements or arrays with an embedded circular arrangement. For the hemianopic patients, the circle was presented in their intact hemifield only. For controls, the hemifield for the circle presentation was counterbalanced across subjects. The participants were instructed to detect the circle by pressing a corresponding button. A wavelet transform based on Morlet wavelets was employed for the calculation of oscillatory GBRs. The early evoked GBR exhibited a larger amplitude and shorter latency for the healthy group compared to hemianopic patients and was associated with behavioral measures. The late total GBR between 200 and 400ms after stimulus onset was significantly increased for Gestalt-like patterns in healthy participants. This effect was not manifested in patients. The present findings indicate deficits in the early and late visual processing of Gestalt patterns even in the intact hemifield of hemianopic patients compared to healthy participants.

Hue and saturation shifts from spatially induced blackness.

We studied changes in the color appearance of a chromatic stimulus as it underwent simultaneous contrast with a more luminous surround. Three normal trichromats provided color-naming descriptions for a 10 cd/m2 monochromatic field while a broadband white annulus surround ranged in luminance from 0.2 cd/m2 to 200 cd/m2. Descriptions of the chromatic field included Red, Green, Blue, Yellow, White, and Black or their combinations. The naming frequencies for each color/surround were used to calculate measures of similarity among the stimuli. Multidimensional scaling analysis of these subjective similarities resulted in a four-dimensional color space with two chromatic axes, red-green and blue-yellow, and two achromatic axes, revealing separate qualities of blackness/lightness and saturation. Contrast-induced darkening of the chromatic field was found to be accompanied by shifts in both hue and saturation. Hue shifts were similar to the Bezold-Brücke shift; shifts in saturation were also quantified. A stage model is proposed to account for the relationships among blackness induction and the inherent nonlinearities in chromatic and achromatic processing.

Irreversible color vision losses in patients with chronic mercury vapor intoxication.

This longitudinal study addresses the reversibility of color vision losses in subjects who had been occupationally exposed to mercury vapor. Color discrimination was assessed in 20 Hg-exposed patients (mean age = 42.4 +/- 6.5 years; 6 females and 14 males) with exposure to Hg vapor during 10.5 +/- 5.3 years and away from the work place (relative to 2002) for 6.8 +/- 4.2 years. During the Hg exposure or up to one year after ceasing it, mean urinary Hg concentration was 47 +/- 35.4 mug/g creatinine. There was no information on Hg urinary concentration at the time of the first tests, in 2002 (Ventura et al., 2005), but at the time of the follow-up tests, in 2005, this value was 1.4 +/- 1.4 microg/g creatinine for patients compared with 0.5 +/- 0.5 microg/g creatinine for controls (different group from the one in Ventura et al. (2005)). Color vision was monocularly assessed using the Cambridge Colour Test (CCT). Hg-exposed patients had significantly worse color discrimination (p < 0.02) than controls, as evaluated by the size of MacAdam's color discrimination ellipses and color discrimination thresholds along protan, deutan, and tritan confusion axes. There were no significant differences between the results of the study in Ventura et al. (2005) and in the present follow-up measurements, in 2005, except for worsening of the tritan thresholds in the best eye in 2005. Both chromatic systems, blue-yellow and red-green, were affected in the first evaluation (Ventura et al., 2005) and remained impaired in the follow-up testing, in 2005. These findings indicate that following a long-term occupational exposure to Hg vapor, even several years away from the source of intoxication, color vision impairment remains irreversible.