| Number plays an important role in our everyday lives. It can be used to express amounts, compare prices, describe weight, and discuss journal impact factors, etc (Cohen Kadosh,&Walsh,2009; Monroe,&Lee,1999). Several studies have investigated the cognition and neural mechanism of numeral processing and reported a typical distance effect on mental representations of numbers (Dehaene,&Akhavein,1995; Dehaene,1996; Moyer,&Landauer,1967; Pinel et al.,2001; Temple,&Ponser,1998). However, it is unclear how numbers are represented in the practical context of everyday judgments, such as price cognition (Cao, et al.,2012).Price cognition refers to the cognitive processes that underlie consumers'judgments concerning the magnitude of a price or the difference between two prices (Adaval,&Monroe,2002; Janiszewski,&Lichtenstein,1999; Niedrich, Sharma,&Wedell,2001; Thomas&Morwitz,2009). The purposes of this paper were to investigate the age developmental characteristic and processing stragies of price comparison from the point of view of numeral processing.Study1(Experiment1) mainly examined whether5-7years old children compared the two different Renmibi (RMB) by integrating the numeral and unit. Number comparison task, RMB recogniton task and RMB comparison task, which consisted of five subtask (only different unit, only same unit—Yuan Yuan comparison and Jiao Jiao comparison, different numeral and unit—consistent and inconsistent) were given to94children aged5-,6-and7-year-old. The results showed that the scores in each task increased as the growth of the age.5years old compared RMB only according to numeral values rather than the unit, following the compositional model;6-year-old children could preliminary integrate two dimensions of numeral and unit, but a few of children judged only according to numeral value, so they took both compostional and holistic strategies, following hybrid model; The scores in each task of7-year-old children all reached the ceiling effect, which suggested they fully judged by the two dimensions of numeral and unit, following the holistic model.Study2investigated which processing stragies people compared the target price with the fixed price, including experiment2and3. In experiment2, participants were instructed to judge whether sixteen two-digit prices with0-ending and9-ending were higher or lower than standard price stimulus (Y55). The results indicated that there were distance effect of both accuracies and reaction times (RTs) based on the whole magnitude.while had nothing to do with the unit (￥). The accuracies of close distance were higher than far distance, and the RTs of the former were also shorter than the latter. However, the performances of Y50and￥59were inferior to the￥49and￥60, respectively. It suggested that participants firstly compared the decade digits, and then continued to processed single digits when they found there were the same decade digit. That was, participants also took separate processing strategy. Thus, Experiment2supported the hybrid model.Experiment3explored which processing strategy people compared the price of different monetary units (Yuan, Jiao and Fen) with fixed price (5jiao). Twelve prices were designed as the target stimuli, which consisted of four digits (1,4,6and9) combined with three Chinese monetary units. Participants had to judge whether the target prices were lower or higher than5jiao while event-related potentials were recorded. The behavioral results did not reveal a main effect of distance when distance was defined in terms of the digits of prices. However, a significant effect of distance was found when distance was defined in terms of the whole magnitude of prices. The electrophysiological results revealed similar distance effects during the350-450ms interval after stimulus onset, with an enhanced negativity for close distance than for far distance. These findings suggested that the numbers and the units of prices were processed holistically rather than separately, following the holistic model.Study3inspected which processing strategy people compared two prices presented serially when the standard prices were varying while ERPs were recorded, including experiment4,5and6. To explore the processing strategy and brain mechanism of price comparison with the same units, experiment4designed two conditions with Yuan Yuan comparison and Jiao Jiao comparison, and asked participants to judge whether the second price became higher or lower than the first price of a goods with the market economy changed. The behavioral results showed that there were distance effects of two conditions, the RTs of close distances were both significantly longer than far distance. The ERP results revealed that there was distance effect of Yuan Yuan comparison during the400-500ms interval after stimulus onset, with an enhanced negativity for close distance than for far distance. In contrast, the distance effect of Jiao Jiao comparison occurred on the350-450ms time windows, with an enhanced positivity for close distance than for far distance. These findings suggested that the numbers and the units of prices were processed according to the whole distances when participants compared two prices with the same units, and supported the holistic model.Experiment5investigated that the processing strategy and brain mechanism when people compared two prices with the same number. The same digit condition and the same unit condition were designed, with the same task and paradigm as experiment4. The behavioral results showed that there were distance effects of two conditions based on the overall magnitudes, the RTs of close distances were both longer than far distances. The ERP results revealed that there was distance effect of the same digit and the same unit conditions on the P3component (latencies were about388ms and404ms, respectively) after stimulus onset, with an enhanced negative-going waveforms for close distance than for far distance. These findings suggested that the numbers and the units of prices were processed according to the whole distances when participants compared two prices with the same digits, following the holistic model.Experiment6examined that the processing strategy and brain mechanism when people compared two prices with the different numbers and units. There were two conditions with consistent and inconsistent according to the size relationships of digits and units. The behavioral and ERP results indicated that there were both conflict effects, regardless of the distance was defined by digit distance or the overall distance. That was, the RTs of inconsistent condition were significantly longer than that of consistent condition; Furthermore, there was conflict effect during350-450ms after stimulus onset, with an enhanced negative-going waveforms for inconsistent condition than for consistent condition, which was similar to the N400component. It might be related to the conflicts of semantic processing, so supported the compostional model. Moreover, when the analysis was defined by the whole distance, there was no distance effect of consistent and inconsistent conditions. However, there were distance effects of accuracy rates when the distance was defined by the digit distance, which the accuracies of close distances were lower than that of far distance. In addition, only the RTs of consistent condition found distance effect, which the RTs for close distance were longer than that for far distance. The ERP data also showed that there was digit distance effect during450-500ms time windows of consistent condition, with the negative-going waveforms for close distance than for far distance. These results suggested that participants processed the digits and units separately when the digits and units of two prices were both different, following the compositional model.Taken together, these results of this paper showed that (1) There might be different processing strategies when5-7years old children compared which RMB was higher.5-,6-and7-year-old followed the compositional model, the hybrid model and the holistic model, respectively.(2) When people judged whether the targer prices were higher or lower than the fixed price, they calculated the whole distance between the target and fixed prices, following the holistic model. However, participants might firstly compare the decade digits, and then continued to processed single digits when they found the same decade digit between the target and fixed prices. That was, they took both holistic and separate strategies, following hybrid model.(3) When people compared two prices of a goods presented serially, they might take holistic processing stragy if the units or digits of two prices were same. However, participants might take flexible strategy and compare the digits and units separately, supporting the compositional model.(4) The semantic processings of price comparison occurred during350-500ms after stimulus onset, which were later than that of numeral processing. On one hand, it might be the price stimuli of this paper include numerals and units, so the identification stages of price comparison task was longer than number comparison task; On the other hand, the former might be more difficult than the latter. Interestingly, the same scalp distributions of semantic processing occurred at the parieto-occipito-temporal electrode sites between the price comparsion task and number comparison task, which might be due to they both include number and magnitude information.
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