Levels-of-processing effects on Chinese character completion: the importance of lexical processing and test cue.

The levels of processing (LoP) effect was studied in Chinese character completion tasks. The same stem cue, either graphemically or semantically related to the target character, was used to generate either a perceptual or a conceptual test. Participants received either direct or indirect instructions, so that the same stem cue also produced either an explicit or an implicit test of memory. This allowed us to examine simultaneously the roles of perceptual versus conceptual test and retrieval intentionality in the LoP effect. No LoP effects were found when the memory test was implicit. LoP effects were also not found for stems and characters related graphemically (perceptually), but were found for stems and characters related semantically (conceptually) when the memory test was explicit. The results are discussed in terms of the importance of lexical processing for character completion tests and the importance of reinstatement of the study process during retrieval for explicit memory tests.

Tone perception in Cantonese and Mandarin: a cross-linguistic comparison.

This study investigated the effects of linguistic experience on tone perception. Both Cantonese (in Experiment 1) and Mandarin (in Experiment 2) tones, including both lexical and nonlexical tones, were presented to three groups of subjects: Cantonese, Mandarin, and English native speakers. Subjects were asked to determine whether two auditorily presented tones were the same or different. The interval between the presentation of the two tones, and the level of interference during this interval, were manipulated. Native speakers did better at discriminating tones from their own languages than the other two groups of subjects, for both lexical and nonlexical tones. Subjects did worst when they were required to count backward during the interstimulus interval. Cantonese speakers were better than both Mandarin and English speakers at discriminating Cantonese tones, and there was no difference between Mandarin and English speakers, except in one condition. Mandarin speakers did better than both Cantonese and English speakers, and Cantonese speakers did better than English speakers, at discriminating Mandarin tones. Results are discussed in terms of the effects of language background, differences between Cantonese and Mandarin tones, and the nature of encoding in short-term memory.

Color improves object recognition in normal and low vision.

Does color improve object recognition? If so, is the improvement greater for images with low spatial resolution in which there is less shape information? Do people with low visual acuity benefit more from color? Three experiments measured reaction time (RT) and accuracy for naming food objects displayed in 4 types of images: gray scale or color, and high or low spatial resolution (produced by blur). Normally sighted Ss had faster RTs with color, but the improvement was not significantly greater for images with low spatial resolution. Low vision subjects were also faster with color, but the difference did not depend significantly on acuity. In 2 additional experiments, it was found that the faster RTs for color stimuli were related to objects' prototypicality but not to their color diagnosticity. It was concluded that color does improve object recognition, and the mechanism is probably sensory rather than cognitive in origin.

Psychophysics of reading. XI. Comparing color contrast and luminance contrast.

Text can be depicted by luminance contrast (i.e., differences in luminance between characters and background) or by color contrast (i.e., differences in chromaticity). We used a psychophysical method to measure the reading speeds of eight normal and ten low-vision subjects for text displayed on a color monitor. Reading speed was measured as a function of luminance contrast, color contrast (derived from mixtures of red and green), and combinations of the two. When color contrast is high, normal subjects can read as rapidly as with high luminance contrast (greater than 300 words/min). Curves of reading speed versus contrast have the same shape for the two forms of contrast and are superimposed when contrast is measured in multiples of a threshold value. When both color and luminance contrast are present, there is no sign of additive interaction, and performance is determined by the form of contrast yielding the highest reading rate. Our findings suggest that color contrast and luminance contrast are coded in similar ways in the visual system but that the neural signals used in letter recognition are carried by different pathways for color and luminance. We found no advantages of color contrast for low-vision reading. For text composed of 6 degrees characters, all low-vision subjects read better with luminance contrast than with color contrast.