The processing of coherent global form and motion patterns without visual awareness

Charles Y L Chung,Sieu K Khuu

doi:10.3389/fpsyg.2014.00195

Abstract

In the present study we addressed whether the processing of global form and motion was dependent on visual awareness. Continuous flash suppression (CFS) was used to suppress from awareness global dot motion (GDM) and Glass pattern stimuli. We quantified the minimum time taken for both pattern types to break suppression with the signal coherence of the pattern (0, 25, 50, and 100% signal) and the type of global structure (rotational, and radial) as independent variables. For both form and motion patterns increasing signal coherence decreased the time required to break suppression. This was the same for both rotational and radial global patterns. However, GDM patterns broke suppression faster than Glass patterns. In a supplementary experiment, we confirmed that this difference in break times is not because of the temporal nature of GDM patterns in attracting attention. In Experiment 2, we examined whether the processing of dynamic Glass patterns were similarly dependent on visual awareness. The processing of dynamic Glass patterns is involves both motion and form systems, and we questioned whether the interaction of these two systems was dependent on visual awareness. The suppression of dynamic Glass patterns was also dependent on signal coherence and the time course of suppression break resembled the detection of global motion and not global form. In Experiment 3 we ruled out the possibility that faster suppression break times was because the visual system is more sensitive to highly coherent form and motion patterns. Here contrast changing GDM and Glass patterns were superimposed on the dynamic CFS mask, and the minimum time required for them to be detected was measured. We showed that there was no difference in detection times for patterns of 0 and 100% coherence. The advantage of highly coherent global motion and form patterns in breaking suppression indicated that the processing and interaction of global motion and form systems occur without visual awareness.

Highlights

It has been well established that the visual system analyses information in the scene in at least two computationally distinct steps in which local scene statistics are first extracted before being integrated to detect global image properties such as the overall shape and motion of objects (e.g., Marr, 1983)
The time taken for Static Glass and global dot motion (GDM) patterns for radial and rotational structure to break suppression as a function of stimulus coherence is plotted in Figures 2A,B respectively
GENERAL DISCUSSION In the present study we investigated the degree to which global form and motion patterns were processed without visual awareness

Summary

Introduction

It has been well established that the visual system analyses information in the scene in at least two computationally distinct steps in which local scene statistics (representing basic visual features such as orientation, contrast, and color) are first extracted before being integrated to detect global image properties such as the overall shape and motion of objects (e.g., Marr, 1983). Neurons in V1 are restricted in their spatial extent of analysis, and only obtain an estimate of local motion, before outputting to higher cortical areas located along the dorsal pathway, such as middle temporal (MT) and medial superior temporal (MST; e.g., Adelson and Movshon, 1982; Newsome and Pare, 1988; Duffy and Wurtz, 1991a,b; Orban et al, 1995) Cells in these areas have large receptive fields and function by pooling the responses of local motion detectors to derive an estimate of the global or overall direction and speed of objects. In particular local form information, such as orientation, is extracted by orientation-tuned cells in V1, before their outputs are combined www.frontiersin.org

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