Born Sabine, Krüger Hannah M, Zimmermann Eckart, Cavanagh Patrick
Centre Attention & Vision, Laboratoire Psychologie de la Perception, Université Paris Descartes, Sorbonne Paris Cité, CNRS UMR 8242Paris, France; Equipe Cognition Visuelle, Faculté de Psychologie et des Sciences de l'Education, Université de GenèveGenève, Switzerland.
Centre Attention & Vision, Laboratoire Psychologie de la Perception, Université Paris Descartes, Sorbonne Paris Cité, CNRS UMR 8242 Paris, France.
Front Syst Neurosci. 2016 Mar 10;10:21. doi: 10.3389/fnsys.2016.00021. eCollection 2016.
Stimuli briefly flashed just before a saccade are perceived closer to the saccade target, a phenomenon known as perisaccadic compression of space (Ross et al., 1997). More recently, we have demonstrated that brief probes are attracted towards a visual reference when followed by a mask, even in the absence of saccades (Zimmermann et al., 2014a). Here, we ask whether spatial compression depends on the transient disruptions of the visual input stream caused by either a mask or a saccade. Both of these degrade the probe visibility but we show that low probe visibility alone causes compression in the absence of any disruption. In a first experiment, we varied the regions of the screen covered by a transient mask, including areas where no stimulus was presented and a condition without masking. In all conditions, we adjusted probe contrast to make the probe equally hard to detect. Compression effects were found in all conditions. To obtain compression without a mask, the probe had to be presented at much lower contrasts than with masking. Comparing mislocalizations at different probe detection rates across masking, saccades and low contrast conditions without mask or saccade, Experiment 2 confirmed this observation and showed a strong influence of probe contrast on compression. Finally, in Experiment 3, we found that compression decreased as probe duration increased both for masks and saccades although here we did find some evidence that factors other than simply visibility as we measured it contribute to compression. Our experiments suggest that compression reflects how the visual system localizes weak targets in the context of highly visible stimuli.
在扫视之前短暂闪现的刺激会被感知为更靠近扫视目标，这一现象被称为扫视周围空间压缩（罗斯等人，1997年）。最近，我们已经证明，即使在没有扫视的情况下，短暂的探测刺激在被掩蔽跟随之后也会被吸引到视觉参考点上（齐默尔曼等人，2014年a）。在这里，我们要问空间压缩是否取决于由掩蔽或扫视引起的视觉输入流的短暂中断。这两者都会降低探测刺激的可见性，但我们表明，仅低探测刺激可见性在没有任何干扰的情况下也会导致压缩。在第一个实验中，我们改变了由短暂掩蔽覆盖的屏幕区域，包括没有呈现刺激的区域和无掩蔽条件。在所有条件下，我们调整探测刺激的对比度以使探测刺激同样难以检测。在所有条件下都发现了压缩效应。为了在没有掩蔽的情况下获得压缩，探测刺激必须以比有掩蔽时低得多的对比度呈现。通过比较在掩蔽、扫视以及无掩蔽或扫视的低对比度条件下不同探测刺激检测率时的定位错误，实验2证实了这一观察结果，并表明探测刺激对比度对压缩有很大影响。最后，在实验3中，我们发现对于掩蔽和扫视，随着探测刺激持续时间的增加，压缩效应会降低，尽管在这里我们确实发现了一些证据，表明除了我们所测量的简单可见性之外的其他因素也对压缩有贡献。我们的实验表明，压缩反映了视觉系统在高可见性刺激背景下如何定位弱目标。
