Hunter-Gatherer Color Naming Provides New Insight into the Evolution of Color Terms

SummaryMost people name the myriad colors in the environment using between two and about a dozen color terms [1], with great variation within and between languages [2]. Investigators generally agree that color lexicons evolve from fewer terms to more terms, as technology advances and color communication becomes increasingly important [3]. However, little is understood about the color naming systems at the least technologically advanced end of the continuum. The Hadza people of Tanzania are nomadic hunter-gatherers who live a subsistence lifestyle that was common before the advent of agriculture (see Supplemental Experimental Procedures, section I; [4]), suggesting that the Hadzane language should be at an early stage of color lexicon evolution. When Hadza, Somali, and US informants named 23 color samples, Hadza informants named only the black, white, and red samples with perfect consensus. Otherwise, they used low-consensus terms or responded “don’t know.” However, even low-consensus color terms grouped test colors into lexical categories that aligned with those found in other world languages [5]. Furthermore, information-theoretic analysis showed that color communication efficiency within the Hadza, Somali, and US language communities falls on the same continuum as other world languages. Thus, the structure of color categories is in place in Hadzane, even though words for many of the categories are not in general use. These results suggest that even very simple color lexicons include precursors of many color categories but that these categories are initially represented in a diverse and distributed fashion

Critical Immaturities Limiting Infant Binocular Stereopsis

PURPOSE. To determine what critical immaturity is responsible for the poor binocular stereopsis of human infants. METHODS. Infant and adult psychometric functions were measured for detection of stereoscopic depth in a random-texture display. A test stimulus defined by horizontal binocular disparity and a distracter stimulus defined by vertical disparity were used. Adults were tested by direct psychophysical methods at several contrast values, and infants by forced-choice preferential looking at 100% contrast. RESULTS. Infant stereoacuity matured from unmeasurable at age 12 weeks to 7.9 arc min at 20 weeks, which was still far from the nominal adult value of 5 to 10 arc seconds. In contrast, infant d-max (maximum disparity) was 86.8 minutes at 20 weeks, which was near the adult d-max of 110.6 minutes. The average maximum level of infant performance at 20 weeks was 77% correct, still far below adult performance. When the adult stereogram was low contrast, adult extrafoveal performance was similar to infant performance. Infant and adult stereo performance was predicted quantitatively, using infant and adult monocular performance in detecting the stereogram texture. Infant and adult stereopsis performance approached, but did not reach, the predicted values. CONCLUSIONS. The infantlike performance of adults tested at low contrast and the similarity of infant maximum percentage of correct data relative to the predicted values suggested that the critical immaturity limiting infant stereopsis is the well-known insensitivity of the infant visual system to contrast. This conclusion supports the clinical use of stereopsis as a screening test for bilateral monocular function in infants. (Invest Ophthalmol Vis Sci

The color communication game

Abstract There is clear diversity among speakers of a typical language in how colors are named. What is the impact of this diversity on the people’s ability to communicate about color? Is there a gap between a person’s general understanding of the color terms in their native language and how they understand a particular term that denotes a particular color sample? Seventy English-speaking dyads and 63 Somali-speaking dyads played the Color Communication Game, where the “sender” in each dyad named 30 color samples as they would in any color-naming study, then the “receiver” chose the sample they thought the sender intended to communicate. English speakers played again, under instructions to intentionally communicate color sample identity. Direct comparison of senders’ samples and receivers’ choices revealed categorical understanding of colors without considering color naming data. Although Somali-speaking senders provided fewer color terms, interpersonal Mutual Information (MI) calculated from color naming data was similarly below optimal for both groups, and English-speaking dyads’ MI did not improve with experience. Both groups revealed superior understanding of color terms because receivers showed better exactly-correct selection performance than was predicted by simulation from their senders’ color-naming data. This study highlights limitations on information-theoretic analyses of color naming data

Hadza Color Terms Are Sparse, Diverse, and Distributed, and Presage the Universal Color Categories Found in Other World Languages

In our empirical and theoretical study of color naming among the Hadza, a Tanzanian hunter-gatherer group, we show that Hadza color naming is sparse (the color appearance of many stimulus tiles was not named), diverse (there was little consensus in the terms for the color appearance of most tiles), and distributed (the universal color categories of world languages are revealed in nascent form within the Hadza language community, when we analyze the patterns of how individual Hadza deploy color terms). Using our Hadza data set, Witzel shows an association between two measures of color naming performance and the chroma of the stimuli. His prediction of which colored tiles will be named with what level of consensus, while interesting, does not alter the validity of our conclusions

A higher order motion region in human inferior parietal lobule: evidence from fMRI

The proposal that motion is processed by multiple mechanisms in the human brain has received little anatomical support so far. Here, we compared higher- and lower-level motion processing in the human brain using functional magnetic resonance imaging. We observed activation of an inferior parietal lobule (IPL) motion region by isoluminant red-green gratings when saliency of one color was increased and by long-range apparent motion at 7 Hz but not 2 Hz. This higher order motion region represents the entire visual field, while traditional motion regions predominantly process contralateral motion. Our results suggest that there are two motion-processing systems in the human brain: a contralateral lower-level luminance-based system, extending from hMT/V5+ into dorsal IPS and STS, and a bilateral higher-level saliency-based system in IPL.status: publishe

A higher order motion region in human inferior parietal lobule : evidence from fMRI

AbstractThe proposal that motion is processed by multiple mechanisms in the human brain has received little anatomical support so far. Here, we compared higher- and lower-level motion processing in the human brain using functional magnetic resonance imaging. We observed activation of an inferior parietal lobule (IPL) motion region by isoluminant red-green gratings when saliency of one color was increased and by long-range apparent motion at 7 Hz but not 2 Hz. This higher order motion region represents the entire visual field, while traditional motion regions predominantly process contralateral motion. Our results suggest that there are two motion-processing systems in the human brain: a contralateral lower-level luminance-based system, extending from hMT/V5+ into dorsal IPS and STS, and a bilateral higher-level saliency-based system in IPL