Olaya İlişkin Potansiyellerin Saklanmış Bilginin Tespitinde Kullanımı: Kelime, Nesne ve Yüz Tanımanın Karşılaştırılması

Abstract

The purpose of this study was to investigate which type of visual concealed information, in the form of text, object and face pictures, would cause distinctive event related potentials. We compared electrophysiological and behavioral data (reaction time and correct button press ratios) of twenty volunteer subjects aged 18-30 years. The subjects attended three-stimulus-protocol which was consisted of text, object and face pictures. Each test was comprised of six different pictures, one of them was meaningful (prob), one of them was target and the others were nonsense (standard) for subject. The subjects were instructed to press a button when they saw target picture and press another button when they saw other pictures. We calculated reaction times and correct button press ratios during button press task. Event related potentials were recorded simultaneously during the button press task. Each subject's event related potential was averaged to compare P300-based event related potential amplitudes. We found a significant increase between prob and target picture's mean P300s amplitudes compared to standard pictures' mean P300s amplitudes in text, object and face picture categories. However, these values were not significant between categories after these values were standardized and then compared. We could not find significant difference between categories in P300 latencies. When mean reaction times are compared, there is significant difference in target pictures reaction times compared to standard pictures reaction times. However, no significance is found in prob reaction times compared to standards' reaction times, even though probs' reaction times have gotten longer. There is not a significant difference in correct button press ratios. According to our results, there is no significant difference among face, text and object categories in detection of meaningful information visuals by concealed information test. Previous studies revealed different results although all of them used the same methods with small alterations. The reason of having different results might be due to simple changes in methods. These subtle changes may affect subject's motivation, or other factors such as cultural and personality differences may be the culprit.