| Abstract [eng] |
Ambiguous figure – is an image typically containing at least two mutually exclusive percepts, which constantly interchange each other. When perception of ambiguous stimuli is examined with the help of electroencephalography, perceived reversals typically evoke a negative potential difference termed Reversal Negativity, which is usually observed around 200-300 ms post-stimulus. The aim of this work was to identify the cognitive interpretation of Reversal Negativity. It may be a selective attention related response, or it may reflect the operation of lower level mechanisms, or reveal the activation of the mechanisms related to subjective awareness. In order to answer these questions two different studies were conducted. At first, it was hypothesized that Reversal Negativity might be an equivalent of N2 posterior contralateral component, or a subtype of Visual Awareness Negativity. The results showed that Reversal Negativity is neither a functional equivalent of N2 posterior contralateral, nor a subtype of Visual Awareness Negativity. Another study dealt with a possible impact of high or low perceptual load on the amplitude of Reversal Negativity. The results revealed that Reversal Negativity was completely suppressed by perceptual load independently of the magnitude of the presented load. Thus it was concluded that Reversal Negativity is an event-related potentials correlate unrelated to selective attention, which represents the perceptual changes of the presented object. |
