Chinese character recognition in mirror reading: evidence from event-related potential

Mirror Generalization During Early Word Recognition

The "recycling hypothesis" posits that the word recognition system is built upon minimal modifications to the neural architecture used in object recognition. In two masked priming lexical decision studies, we examined whether "mirror generalization," a phenomenon in object recognition, occurs in word recognition. In Study 1, we found that mirrored repetition and mirrored transposed letter primes elicited significant and equivalent priming effects for mirrored targets. In Study 2, we found that mirrored and non-mirrored repetition primes both significantly facilitated processing of mirrored targets, but the priming effect was much larger for non-mirrored primes. In both studies, we also found evidence of gender differences as females showed faster response times and a larger mirror priming effect compared to males. Taken together, we conclude that mirror generalization occurs in the early orthographic stage of word recognition, but not in the later stage of lexical access, and there is a gender difference when reading mirror words.

Investigation of the mirrored-word reading paradigm for BCI implementation

Brain-computer interface (BCI) applications such as keyboard control and vehicular navigation present significant assistive merit for disabled individuals. However, there are limitations associated with BCI paradigms which restrict a wider adoption of BCI technology. For example, rapid serial visual presentation (RSVP) paradigms can induce seizures in photosensitive epileptic subjects. This paper evaluates the novel mirrored-word reading paradigm (MWRP) for BCI implementation using an offline experimental study. The offline study obtained an average single-trial classification accuracy of 74.10%. The results also demonstrate that the use of multiple trials for classification can increase the accuracy as is common with BCIs. The developed MWRP-based BCI also utilized a low presentation frequency which averts the possibility of paradigm induced photosensitivity. However, there are multiple avenues for future work. The MWRP can be implemented in the online format for real-time device control. For example, a vehicular application platform can be used where the word orientation represents directions for travel. The MWRP can also be investigated across a wider range of stimulus presentation parameters such as timing, color and stimulus size. Such studies can be used to suggest further improvements to the paradigm which can enhance its applicability for online device control.

The Inversion Effect for Chinese Characters is Modulated by Radical Organization

In studies of visual object recognition, strong inversion effects accompany the acquisition of expertise and imply the involvement of configural processing. Chinese literacy results in sensitivity to the orthography of Chinese characters. While there is some evidence that this orthographic sensitivity results in an inversion effect, and thus involves configural processing, that processing might depend on exact orthographic properties. Chinese character recognition is believed to involve a hierarchical process, involving at least two lower levels of representation: strokes and radicals. Radicals are grouped into characters according to certain types of structure, i.e. left-right structure, top-bottom structure, or simple characters with only one radical by itself. These types of radical structures vary in both familiarity, and in hierarchical level (compound versus simple characters). In this study, we investigate whether the hierarchical-level or familiarity of radical-structure has an impact on the magnitude of the inversion effect. Participants were asked to do a matching task on pairs of either upright or inverted characters with all the types of structure. Inversion effects were measured based on both reaction time and response sensitivity. While an inversion effect was observed in all 3 conditions, the magnitude of the inversion effect varied with radical structure, being significantly larger for the most familiar type of structure: characters consisting of 2 radicals organized from left to right. These findings indicate that character recognition involves extraction of configural structure as well as radical processing which play different roles in the processing of compound characters and simple characters.

The Limited Impact of Exposure Duration on Holistic Word Processing

The current study explored the impact of stimuli exposure duration on holistic word processing measured by the complete composite paradigm (CPc paradigm). The participants were asked to match the cued target parts of two characters which were presented for either a long (600 ms) or a short duration (170 ms). They were also tested by two popular versions of the CPc paradigm: the “early-fixed” task where the attention cue was visible from the beginning of each trial at a fixed position, and the “delayed-random” task where the cue showed up after the study character at random locations. The holistic word effect, as indexed by the alignment × congruency interaction, was identified in both tasks and was unaffected by the stimuli duration in both tasks. Meanwhile, the “delayed-random” task did not bring about larger holistic word effect than the “early-fixed” task. These results suggest the exposure duration (from around 150 to 600 ms) has a limited impact on the holistic word effect, and have methodological implications for experiment designs in this field.

ERP evidence for the time course of mental rotation in the mirror reading of Chinese words

The present study investigated the neuro-mechanism of mirror reading using two-character Chinese words and event related potentials (ERPs). Seventeen Chinese participants performed a lexico-semantic decision task on normal or reversed words (presented normally or in mirror images). Behavioral results showed a clear processing advantage for the normal words, compared with the reversed ones. ERP components including N200, N400, and LPC showed differences between the two word types, indicating the presence of mental rotation and its overlap in time with the two major stages of word recognition, namely word form identification and lexico-semantic processing. The results support parallel processing models proposing that mental rotation takes place parallelly with word recognition in mirror reading.

Electrophysiological correlates of early processing of visual word recognition: N2 as an index of visual category feature processing

A fundamental question in second language learning is how the brain separates inputs from different languages into distinct representation systems prior to semantic activation. The present study investigated this question using a silent reading task in which Latin letters and simple Chinese characters (including real characters and pseudocharacters) appeared randomly for 100 milliseconds (ms). High-density event-related potentials were employed to record the electrophysiological correlates of visual word recognition prior to motor response. The results showed that real Chinese characters and pseudocharacters produced a larger N2 response than letters within 200-300ms time window. However, no significant differences between real Chinese characters and pseudocharacters were found. The separation of two languages into their own systems might occur in the time window when N2 was elicited. The segregation of real Chinese characters and pseudocharacters was observed in a later time window (350-450ms). The category feature processing of stimuli might be responsible for the N2 response; the processing allows stimuli of the same category to be analyzed in their specific units and distinguishes different stimuli.