Behavioral Experiment:Categorical color perception--论文代写范文精选

通过计算偏好分数,寻找每一个婴儿,我们发现的证据表明婴儿会根据颜色类别进行区分，婴儿的新奇偏好显著增加。这个结果意味着在婴儿之间是存在的。下面的paper代写范文进行详述。

Abstract
We confirmed whether the color-category boundary in infants is similar to the color-category boundary of adults by conducting the following behavioral experiment, using a familiarization/noveltypreference procedure. Infants were familiarized with stimuli of one color and then tested for novelty preference with the original color and a novel color presented simultaneously. Infants were tested whether, for example, B1 was perceived as a color in the same group as B2 and different from the group of G1 and G2. Stimulus pairs differed in terms of between- or within-category pairs. Significant preference for only novel stimuli in a new category, but not for stimuli of the same category, would indicate the presence of categorical perception and the boundary of a color category in infants. This inference is based on the consensus that the effect of familiarization cannot be generalized across a category boundary (3, 4). 

We used three conditions (B1/B2, B1/ G1, and G1/G2), depending on the color pair for the test of novelty preference. For instance, in the B1/G1 condition, the infants were familiarized with either B1 or G1 in the familiarization phase, and then presented with the pair of B1 and G1 in the posttest phase. By calculating preference scores, the relative looking time for the novel stimuli divided by the total looking time for each infant, we found evidence indicating that infants discriminated stimuli according to color categories, as shown in Fig. 3. 

The novelty preference was evaluated by preplanned t tests to compare the scores between pre- and posttest conditions. The infants’ novelty preferences increased significantly only when the posttest stimulus was the between-category pair [B1/G1: t(11) = 3.90, P < 0.01; B1/B2: t(11) = 0.03, P = 0.975: n.s.; G1/G2: t(11) = 0.90, P = 0.386: n.s.]. This result implies that a category border was present between colors B1 and G1 in infants. To examine whether a spontaneous preference existed, a two-tailed t test was performed on the data of the pretest phase against the chance level (50%). No preference scores in the pretest phase were significantly different from chance [B1/G1 condition: t(11) = 0.32, P = 0.75; B1/B2 condition: t(11) = 0.57, P = 0.57; G1/G2 condition: t(11) = 0.23, P = 0.82; all n.s.]. Therefore, the infants appear to have distinguished the colors based on category differences, and not by simple color preference. These findings support the hypothesis that 5- to 7-mo-old infants distinguish color categories, and that the color pairs we used in the NIRS experiment (B1/G1 vs. G1/G2) differed in relation to the border of a color category. It must be noted that the absence of a novelty preference does not imply the inability of infants to discriminate colors within a category. A previous study (5) has demonstrated that infants could discriminate the same set of colors using a visual search task. Additionally, significant activation in NIRS responses for both color pairs in the occipital region (Fig. 2 B and C) may imply that both pairs of color alternations could evoke responses in the infants’ early visual cortex. Therefore, it is possible that the novelty preference measures were not sufficiently sensitive to detect the infants’ ability for discriminating two colors in the same category.

General Discussion 
Our findings have revealed, for the first time to our knowledge, that 5- to 7-mo-old infants have similar hemodynamic responses as adults to color alternations in relation to a color-category border. This result is consistent with the behavioral data of categorical color perception in infants (3–5, 13). These results also support the idea that categorical color perception is formed by a perceptual process that is plausibly based on an innate organization of color categories in visual processing or experience in the visual environment, and that can be independent of language. Our results indicated that different categories of colors are represented differently in infants in the OT regions, similar to the results in adults (Fig. 2 and Fig. S3), but not in the early visual cortex (Fig. 2). Furthermore, the responses in the OT regions are likely driven by the color category, rather than by mere perceptual color difference. These results are consistent with previous studies in both macaque monkeys and humans (18–20, 31, 32), which found the presence of categorical encoding of color in the ventral pathway. Previous functional neuroimaging studies have associated area V4, located in the fusiform gyrus, as an important site for color perception in the adult human brain (33–35). 

A recent fMRI study reported that the categorical clustering of neural representation for color-naming was found in the ventral visual areas V4v and VO1 (20), whereas these areas seem to change their responses flexibly under different tasks (19), probably according to the top-down signal from higher order areas that define categories (31). An electrophysiological study in macaque monkeys’ inferior temporal cortex (18) showed the presence of neurons with selectivity for color categories, which was highly similar to the categories measured by psychophysics in humans (32). According to the estimation of correspondence between the channel positions in the international 10–20 EEG system and their anatomical loci (36), the significant activity shown in our grouped channel analysis was near the border of the middle temporal gyrus and the fusiform gyrus, which are close to Wernicke’s area in adults; this region of significant activity may suggest some relevance to lingual processes. 

However, a recent NIRS study revealed that Wernicke’s area begins to take part in the lingual process at 13–14 mo after birth, but not in infants at 6–7 mo of age (37). Clifford et al. (15) have shown that the between-category stimuli elicited a larger peak amplitude of ERPs than the withincategory stimuli, but failed to detect the lateralization (9, 13, 14). In the present study, using NIRS to measure categorical color responses, hemispheric asymmetry was not observed. In addition, lateralization of the categorical effect (9) could not be replicated by an extensive series of experiments in two recent psychophysical studies (16, 17). 

Three possible explanations for this absence of significant laterality are as follows: (i) the lateralization of categorical color perception is not robust or has a weak effect size, such that the statistical power was too low and was not reliably detected; (ii) it could be restricted to certain tasks; or (iii) it cannot be measured as an NIRS response. Thus, the direct relationship between color categorization and hemispheric lateralization needs to be reconsidered. The origin and nature of color categories have been concerns of researchers from a range of disciplines for many decades. 

There is converging behavioral evidence for categorical responses to color in prelinguistic infants (3, 4). Furthermore, it has been reported that a chimpanzee could classify Munsell samples into several categories in a similar way to humans (38). The results of the present study imply that colors in different categories are differently represented in the visual cortex of 5- to 7-mo-old infants. Our findings support the hypothesis that categorical color perception does not necessarily originate from language. 

A recent study that applied cluster analysis (39) to the data of the World Color Survey (www1.ICSI.Berkeley.EDU/wcs/), a corpus of color-naming data from 110 unwritten languages, revealed that the particular structure of color terms used by each language is drawn on a set of about three to six universal color-naming systems. Notably, the results of that study suggested that the pattern of categorization for colors between blue and green could be classified into about four types of “motifs” that are common across various mother languages, original habitations, and cultural backgrounds. On the other hand, there are several other studies in anthropology, cognitive science, and linguistics fields that argue the acquisition of color terms can modify the perceptual border of color categories, such that the same color would be categorized into different categories by different language speakers (40–42). Taken together, it seems that “some categorical color distinctions apparently exist prior to language, and then may be reinforced, modulated, or eliminated by learning a particular language,” as was suggested in a previous study (8).

Materials and Methods 
Participants. All infants were full term at birth and were healthy at the time of the experiment. Ethical approval for this study was obtained from the Ethical Committee at the Chuo University (2012-8). Written informed consent was obtained from the parents of the participants. None of the participants’ parents reported any family history of color deficiency. The participants in the infant NIRS measurement were 24 healthy infants (12 infants for the bilateral OT region measurement and 12 infants for the occipital region measurement) ranging from 5 to 7 mo of age (10 males and 14 females; mean age = 182.3 d, ranging from 154–226 d). An additional 18 infants were excluded because of an insufficient number of successful trials for analysis (fewer than three trials for either the between- or within-category condition) due to fussiness. Thirty-six infants aged 5–7 mo (16 males and 20 females; mean age = 186.9 d, ranging from 143–221 d) participated in the behavior experiment. Another 18 infants were tested but were excluded from the analysis because of fussiness or a side bias.

Apparatus
Each infant sat on his or her parent’s lap in an experimental booth throughout the experiment. A 21-inch color cathode ray tube (CRT) display (Diamond Pro-2070SB; Mitsubishi Electric Co.) was used to present visual stimuli. The display was placed in front of the infant at a distance of about 40 cm. The infant’s looking behavior was monitored by a hidden video camera set below the CRT display, and the stimulus presentation was controlled by an experimenter. Stimuli were generated by a computer-controlled visual stimulus generator (ViSaGe; Cambridge Research Systems) with a 12-bit resolution per each primary color after a careful photometric calibration. The NIRS instrument was a Hitachi ETG-4000 system. We used a pair of sensor-probe holders, each of which contained nine optical fibers (3 × 3 arrays), and recorded changes in oxyHb and deoxy-Hb concentrations with 12 channels in each holder. For the measurement of bilateral OT regions, the center of each probe holder was placed slightly below T5/T6 in the international 10–20 EEG system (Fig. 1B). For the occipital region measurement, we used 12 channels (one holder set) only, and the center of the holder was placed slightly above Oz (Fig. 1B, Right). Details of the NIRS instrument are given in Supporting Information.(paper代写)

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