Academic journal article Attention, Perception and Psychophysics

Using Ambiguous Plaid Stimuli to Investigate the Influence of Immediate Prior Experience on Perception

Academic journal article Attention, Perception and Psychophysics

Using Ambiguous Plaid Stimuli to Investigate the Influence of Immediate Prior Experience on Perception

Article excerpt

Published online: 8 October 2013

(Q> Psychonomic Society, Inc. 2013

Abstract In a series of three experiments, we used an ambiguous plaid motion stimulus to explore the behavioral and electrophysiological effects of prior stimulus exposures and perceptual states on current awareness. The results showed that prior exposure to a stimulus biased toward one percept led to subsequent suppression of that percept. In contrast, in the absence of stimulus bias, prior perceptual experience can have a facilitative influence. The suppressive effects caused by the prior stimulus were found to transfer to an ambiguous plaid test stimulus rotated 180° relative to the adaptation stimulus, but were abolished if (1) the ambiguous test stimulus was only rotated 90° relative to the adaptation stimulus or (2) the adaptation stimulus was heavily biased toward the component grating percept. Event-related potential recordings were consistent with the involvement of visual cortical areas and suggested that the influence of recent stimulus exposure may involve recruitment of additional brain processes beyond those responsible for initial stimulus encoding. In contrast, the effects of prior and current perceptual experience appeared to depend on similar brain processes. Although the data presented here focus on vision, the work is discussed within the context of data from a parallel series of experiments in audition.

Keywords Multistability * Vision * Audition * Motion * Rivalry * Electroencephalography

To visualize and identify the time ranges and electrodes expressing maximal differences, we first calculated difference waves from the grand-averaged original waveforms between conditions of interest. The mean event-related potential (ERP) amplitudes were then calculated from the original waveforms for the identified time ranges and electrodes expressing maximal differences. The difference waves were not used for statistical analysis; rather, the original waveforms were used, as they typically have better signal-to-noise ratios. Note that mean amplitude values can reflect both changes in amplitude and latency of neiuonal soiuces and are less susceptible to noisy data than are peak amplitude/latency measiuements (Piéton et al., 2000). Mean amplitudes were averaged across electrode sites for each participant and submitted to ANOVAs.

How the brain generates a perceptual experience from the current sensory input remains a great mystery of science. To investigate this question many researchers use ambiguous stimuli that are perceptually bistable. The term "bistable" means that an observer experiences continual switches in perceptual state, despite observing an unchanging stimulus (Leopold & Logothetis, 1999; Long & Toppino, 2004). Importantly, the balance between the relative dominance of the different perceptual interpretations is not fixed. Rather the observer's perceptual state appears to depend heavily on the combined influence of the current stimulus properties (Long & Toppino, 2004) and temporal context in which it is experienced, both in respect to previous stimulus exposure (Brascamp, Knapen, Kanai, van Ee, & van den Berg, 2007; Kanai & Verstraten, 2005; Maloney, Dal Martello, Sahm, & Spillmann, 2005) and perceptual history (for a review, see Pearson & Brascamp, 2008). These effects of prior stimulus exposure and prior perceptual interpretations provide valuable insights into the mechanisms that determine one's current conscious experience.

In a series of experiments, we used the auditory stream segregation paradigm to explore the influence of past experience on an observer's subsequent perceptual grouping in audition (Snyder, Carter, Hannon, & Alain, 2009; Snyder, Carter, Lee, Hannon, & Alain, 2008; Snyder, Holder, Weintraub, Carter, & Alain, 2009). This paradigm involves the presentation of low tones (A), high tones (B), and silences (-) in a repeating ABApattem (Bregman & Campbell, 1971; Van Noorden, 1975). …

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