Crossmodal Correspondence Between Tonal Hierarchy and Visual Brightness: Associating Syntactic Structure and Perceptual Dimensions Across Modalities

Crossmodal correspondences (CMC) systematically associate perceptual dimensions in different sensory modalities (e.g., auditory pitch and visual brightness), and affect perception, cognition, and action. While previous work typically investigated associations between basic perceptual dimensions, here we present a new type of CMC, involving a high-level, quasi-syntactic schema: music tonality. Tonality governs most Western music and regulates stability and tension in melodic and harmonic progressions. Musicians have long associated tonal stability with non-auditory domains, yet such correspondences have hardly been investigated empirically. Here, we investigated CMC between tonal stability and visual brightness, in musicians and in non-musicians, using explicit and implicit measures. On the explicit test, participants heard a tonality-establishing context followed by a probe tone, and matched each probe to one of several circles, varying in brightness. On the implicit test, we applied the Implicit Association Test to auditory (tonally stable or unstable sequences) and visual (bright or dark circles) stimuli. The findings indicate that tonal stability is associated with visual brightness both explicitly and implicitly. They further suggest that this correspondence depends only partially on conceptual musical knowledge, as it also operates through fast, unintentional, and arguably automatic processes in musicians and non-musicians alike. By showing that abstract musical structure can establish concrete connotations to a non-auditory perceptual domain, our results open a hitherto unexplored avenue for research, associating syntactical structure with connotative meaning.

Magnitude to luminance conversions and visual brightness of the night sky

ABSTRACT The visual brightness of the night sky is not a single-valued function of its brightness in other photometric bands, because the transformations between photometric systems depend on the spectral power distribution of the skyglow. We analyse the transformation between the night sky brightness in the Johnson–Cousins V band (mV, measured in magnitudes per square arcsecond, mpsas) and its visual luminance (L, in SI units cd m−2) for observers with photopic and scotopic adaptation, in terms of the spectral power distribution of the incident light. We calculate the zero-point luminances for a set of skyglow spectra recorded at different places in the world, including strongly light-polluted locations and sites with nearly pristine natural dark skies. The photopic skyglow luminance corresponding to mV=0.00 mpsas is found to vary in the range 1.11–1.34 × 105 cd m−2 if mV is reported in the absolute (AB) magnitude scale, and in the range 1.18–1.43 × 105 cd m−2 if a Vega scale for mV is used instead. The photopic luminance for mV=22.0 mpsas is correspondingly comprised between 176 and 213 μcd m−2 (AB), or 187 and 227 μcd m−2 (Vega). These constants tend to decrease for increasing correlated colour temperature (CCT). The photopic zero-point luminances are generally higher than the ones expected for blackbody radiation of comparable CCT. The scotopic-to-photopic luminance (S/P) ratio for our spectral data set varies from 0.8 to 2.5. Under scotopic adaptation the dependence of the zero-point luminances with the CCT, and their values relative to blackbody radiation, is reversed with respect to photopic ones.

Optical Identification of the Millisecond Pulsar J0621+2514

Using the SDSS and Pan-STARRS1 survey data, we found a likely companion of the recently discovered binary γ-ray radio-loud millisecond pulsar J0621+2514. Its visual brightness is about 22 mag. The broadband magnitudes and colours suggest that this is a white dwarf. Comparing the data with various white dwarfs evolutionary tracks, we found that it likely belongs to a class of He-core white dwarfs with a temperature of about 10 000 K and a mass of ≲ 0.5 M⊙. For a thin hydrogen envelope of the white dwarf, its cooling age is ≲ 0.5 Gyr which is smaller than the pulsar characteristic age of 1.8 Gyr. This may indicate that the pulsar age is overestimated. Otherwise, this may be explained by the presence of a thick hydrogen envelope or a low metallicity of the white dwarf progenitor.

Cross-modal correspondences and affect in a Schubert song

Light, distance and motion are prominent features in Heine’s ‘Am fernen Horizonten’. A city is veiled in dusk, the sun rises from the earth and the boatman rows with sad strokes. Using empirical findings on cross-modal and affective associations with sounds, we examine Schubert’s interpretation and illustration of these metaphorical dimensions in ‘Die Stadt’. Focusing on local variations in tempo and dynamics, we analyse how the emotional and cross-modal connotations of the song are modified in three performances, provindinginsight into the interrelationship between cross-modal and affective connotations of musical sound. Such interrelationships may suggest complex and often equivocal musical meanings. For example, emotional ‘distance’ is associated with physical distance, as modulated by loudness; visual brightness, as modulated by pitch and timbre, can be painful when unveiling a ‘dark’ memory. Thus, our analysis indicates how musical structures and contours may suggest and interact with perceptual and metaphorical shape in multiple dimensions.

Spectral optimisation and a novel lighting-design space based on circadian stimulus

With the recent advances in photobiology research and light-emitting diode technology, lighting considering circadian effects and the potential health benefits attract much attention. In this study, we demonstrate that the common practice of spectral optimisation of light for high visual efficacy can potentially lead to very inefficient delivery of circadian stimulus, which contributes to the lack of circadian entrainment that is likely to happen in indoor environments with only electric lighting. To optimise spectra of white light-emitting diodes for circadian efficacy, a four-component colour-mixing method with explicit analytical solutions is introduced. Energy-saving up to 29% is achieved at a target circadian stimulus of 0.35, by switching from the traditional maximum-visual-efficacy strategy to a maximum-circadian-efficacy strategy. Moreover, we propose a framework of a novel lighting-design space which allows practitioners to explore the possible combinations of circadian stimulus, visual illuminance and colour temperature. Solutions are provided for scenarios where activation of the circadian system should be avoided while a reasonable visual brightness appearance is maintained.

Does red eye fluorescence in marine fish stand out? In situ and in vivo measurements at two depths

Since the discovery of red fluorescence in fish, much effort has been made to elucidate its potential contribution to vision. However, whatever that function might be, it always implies that the combination of red fluorescence and reflectance of the red iris is sufficient to generate a visual contrast. Here, we present in vivo iris radiance measurements of T. delaisi under natural light fields at 5 and 20 m depth. We also took substrate radiance measurements of shaded and exposed foraging sites at those depths. To assess the visual contrast that can be generated by the red iris, we then calculated iris brightness in the 600-650 nm “red” waveband relative to substrate radiance. At 20 m depth, T. delaisi iris radiance substantially exceeded substrate radiance in the red waveband, regardless of exposure, and despite substrate fluorescence. Given that downwelling light in the 600-650 nm range is negligible at this depth, we can attribute this effect to iris fluorescence. As expected, contrasts were much weaker in 5 m – despite the added contribution of iris reflectance, but we identified specific substrates and conditions under which the pooled radiance caused by red reflectance and fluorescence still exceeded substrate radiance in the same waveband. Due to the negative effect of anesthesia on iris fluorescence these estimates are conservative. We conclude that the requirements to create visual brightness contrasts are fulfilled for a wide range of conditions in the natural environment of T. delaisi.