The Influence Of Object Similarity On Visual Working Memory Encoding And Retrieval

Similarity is defined as the psychological proximity among multi-representationsin cognitive psychology. Some researchers (Conrad,1964; Hue&Erickson,1988;Fallon, Groves,&Tehan,1999; Logie, Sala, Wynn,&Baddeley,2000; Jalbert, Saint-Aubin,&Tremblay，2008; Luria, Sessa, Gotler, Jolicoeur,&Acqua1,2009; Rowe,Hasher,&Turcotte,2010) considered that the similarity could cause interferencesbetween representations and retention in visual working memory, so playing anegative effect on memory performance；Other researchers (Lipinski&Aktunc,2005;Karlsen, Gravir, Johannessen, Endestad,&Lian,2007; Mate&Baque,2009; Lin&Luck,2009; Johnson, Spencer, Luck,&Schoner,2009; Sanocki&Sulman,2011;顾本柏，2011) argued that the precision of similar objects was improved, or thememory load was decreased, so similarity played a positive effect on memoryperformance. At present, the experimental methods were different, the similarity ofobjects may have a positive effect，or negative effect，or indistinct effect. Besides，the similarity effect was confined to explain the experimental method (Avons&Mason,1999). Thus，the mechanism of similarity effect on visual working memory(VWM) representation is not clear until now. The present study aimed to investigatethe mechanism of object similarity effect on VWM encoding and retrieval. The studyincluded four experiments. Experiment1，in a visual search task, aimed to test thevalidity of the discrimination of object orientation characteristics similarity.Experiment2, by using a change-dectection task, was to examine the influence ofobject orientation characteristics similarity on encoding of VWM. By using ERP,experiment3was to demonstrate the mechanism of positive similarity effect.Experiment4was to analyze the influence of object similarity on retrieval of VWMby using a recognition task. The results showed that, in the encoding phase, theperformance of four similar objects to be remembered was significantly better thanfour dissimilar objects’s. Using the contralateral delay activity’s(CDA) amplitude as index, regardless of the number of objects to be remembered (2,3or4object), similarobjects’s CDA amplitude were significantly lower than dissimilar objects’s; whensimilar objects and dissimilar objects’s CDA amplitude maximized, correspondingobject number is three. In the retrieval stage, the performance of dissimilar objects tobe recognized was significantly better than similar objects’s. When the similar objectswere encoded, the performance of similar object to be recognized was the worst.Our study concluded the following conclusions:1. To be closed or achieved individual working memory capacity, objectsimilarity in visual working memory encoding was playing an obvious positive effect;and under the individual working memory capacity, similarity positive effect was notobvious.2. Similarity positive effect was due to similarity simplified the amount of objectrepresentations to be remembered, which could reduce the memory load; and theprecision of similar objects and dissimilar objects were same.3. The effect of similarity in visual working memory representation was notconstant. Object similarity in visual working memory retrieval played a negativeeffect. The similarity had interaction between encoding and retrieval stage. Whensimilar objects were encoded and retrieved, the negative effect of similarity was themost obvious.