Abstract:

Color diagnosticity is the degree to which a color is associated with or symbolizes a particular object. Typical color is often as-sociated with high color diagnostic objects and activates the visual (perceptual) or semantic (conceptual) knowledge in long-term memory. However, the relationship between different processing levels (perceptual and conceptual) of object color information and episodic memory retrieval components (familiarity and recollection) remains poorly understood. It is hypothesized that color infor-mation can facilitate memory encoding at the perceptual level but inhibit it at the conceptual level. In recognition retrieval, color has a greater impact on familiarity and recollection at the perceptual level, while at the conceptual level, recollection is more affected than familiarity.
In the present study, event-related potential (ERP) and a study-test paradigm were used to investigate the effects of color consis-tency (visual color input and object color knowledge) on episodic memory encoding and retrieval by using pictures and names of objects with high color diagnosticity. Twenty-seven college students participated in experiment 1. During the study phase, a picture of an object in its diagnostic color (such as a red apple) or non-diagnostic color (such as purple banana) was presented on a white background for 500ms. The participants were asked to determine whether the color of the object in each picture was consistent with its actual (diagnostic) color. During the test phase, participants provided old/new judgments about the objects that had appeared in the study phase and the equal number of new items. Twenty-five college students participated in experiment 2. A similar procedure was used for experiment 2, except that items were the names of the objects in their diagnostic or non-diagnostic color rather than pictures. During both experiments, the participants responded by pressing a mouse button. Their reaction time and EEG (electroencephalo-graphy) were recorded.
The results of experiment 1 showed that, during the encoding phase, color-inconsistent objects were identified less accurately and more slowly, and this triggered a larger N400 than the color-consistent ones. During the retrieval phase, the color-consistent ob-jects were recalled more quickly and accurately, and this triggered larger FN400 (frontal negativity) values than the color-inconsistent objects. However, the opposite effects were observed in experiment 2. Color-inconsistent object names were identified more quickly and accurately, and they elicited the same ERP wave as the color-consistent names. During the recognition stage, the color had an effect only during the period of late positive components (LPCs).
In conclusion, color was found to have different effects on encoding and retrieval of episodic memory at both the perceptual and semantic levels. (1) Color had different effects on item coding at the perceptual and semantic levels. Color consistency was found to help the viewer identify objects at the perceptual level, but it hindered object identification at the semantic level. (2) Color congru-ence was here found to promote familiarity and recollection in object retrieval (perceptual level), but it only improved recollection of an object’s name (conceptual level). (3) The consistency effect in the processing of object name recognition showed that color was closely related to object name, and it also affected the semantic representation of objects, which further supported the spreading acti-vation model.

Key words: color diagnosticity, episodic memory, ERPs, familiarity, recollection