Abstract: An ERP experiment was conducted with the purpose of exploring how icon concreteness impacts on the recognition process. Recognition Potential (RP) is an early event-related potential (ERP) that occurs when subjects see recognizable stimuli. Icon concreteness was defined to be the extent to which icons pictorially represent objects, places or people. Concrete icons are designed to look like the objects in the real world, for example, a printer, a disc, and a stamp. In contrast, abstract icons are likely to use symbols or geometric constructs that do not have real-world references, such as arrows, shapes and punctuation marks. Self-report studies found that people consider concrete icons easier to interpret. However, the priority of concrete icons in subjective preference is not always reflected in behavior experiments. 17 experienced GUI users participated in the research. We adopted a Rapid-Stream Stimulation (RSS) paradigm, a method considered to be helpful in evoking RPs. Stimuli were displayed with a stimulus onset asynchrony (SOA) of 250 ms. Test stimuli and control stimuli were presented periodically, after about six or seven background stimuli. The subjects were instructed that, during the experiment, they should press a key as rapidly as possible when detecting an icon. The first recording sequence begins after two trial sequences. An E-prime program was used to determine the order of stimulus presentation, the control rest time between sequences, and the collected behavior reaction data. During the experiment, stimuli were presented in the centre of a 17-inch Dell display. The subjects’ behavioral data were first exported to Excel for pretreatment. EEG data were recorded from a 128-channel Geodesic Sensor Net with KCl electrodes and analysed by a Geodesic Photogrammetry System (Electrical Geodesics Ins., Eugene, OR, USA). The RP amplitude and latency was measured at a 180-350 ms time window at a group of electrodes at bilateral inferior parieto-occipital area (P1, P5, O1, PO3, PO7, P2, P6, PO8, PO4 and O2) for each subject. The static data were exported to SPSS for further analysis. Result show: 1) there was a very significant difference in the RP amplitude for concrete, medium and abstract icons F(9, 480)=27.82, p<.001, η2=0.769, observed power=1.000. The more concrete the icon is, the smaller the RP it evokes. Our finding suggests that less effort was involved during the intermediate visual reprsentation which intergrated information from various pathways and then achieve particular form analysis for concrete icons than abstract icons. 2) The RT was slightly but significant shorter for concrete icons than for abstract icons F(2, 48)=14.854, p<0.001, η2=0.481, observed power=0.998. But concreteness has not significant effect on the RP latency F(18, 480)=1.123, p>.05, η2=0.063, observed power=0.776. The psychological mechanism behind this phenomenon is discussed. According to the results, icons that depict real-world objects can save the cognitive energy of users even though they are experienced.

Key words: icon, icon concreteness, ERP, Recognition Potential

摘要： 人们主观上认为形象图标容易识别,然而以反应时为指标的行为实验发现,随着熟悉度增加,形 象优势逐渐消失。本研究采用事件相关电位(ERPs)技术,记录分析了 17 名熟练用户在识别图标时的识别电 位(RP)。结果显示:图标形象度对 RP 在潜伏期无显著差异,但形象图标反应时比抽象图标短,且形象图标 的RP波幅显著小于抽象图标。这一结果说明识别形象图标在类别分拣进程中处理的特征信息量较抽象图标少。

关键词: 图标, 图标形象度, 事件相关电位(ERP), 识别电位(RP)