Second-order change blindness

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In recent talks in Warsaw (IACAP) and Krakow (ASSC), I sketched some experimental designs that would allow us to see whether visual experience is backward-looking or forward-looking (do we experience things as they were, or as they will be? Or neither?).  When I shared the early form of these designs with Matt Jaquiery a few years back, he pointed out that they assumed an affirmative answer to a question which had not yet been answered (or asked) in the experimental literature: do people suffer from change blindness with respect to second-order spatio-temporal visual properties?  Specifically, will the usual distractors (white flash, “mud splashes”, etc) result in subjects failing to notice a change of trajectory of a visual object?  Matt then designed and conducted a web-based experiment to answer this question.  Nora Andermane helped out by running a lab-based version.  The answer is yes.  A paper presenting our results is now under review with PLoS ONE.  The bioRxiv preprint (“Trajectory changes are susceptible to change blindness manipulations”) is available now (comments welcome!):

Here’s the abstract:

People routinely fail to notice that things have changed in a visual scene if they do not perceive the changes in the process of occurring, a phenomenon known as ‘change blindness’. The majority of lab-based change blindness studies use static stimuli and require participants to identify simple changes such as alterations in stimulus orientation or scene composition. This study uses a ‘flicker’ paradigm adapted for dynamic stimuli which allowed for both simple orientation changes and more complex trajectory changes. Participants were required to identify a moving rectangle which underwent one of these changes against a background of moving rectangles which did not. The results demonstrated that participants’ ability to correctly identify the target deteriorated with the presence of a visual mask and a larger number of distractor objects, consistent with findings in previous change blindness work. The study provides evidence that the flicker paradigm can be used to induce change blindness with dynamic stimuli, and that changes to predictable trajectories are detected or missed in the similar way as orientation changes.

Multi-sensory integration without consciousness

This morning, Tad Zawidzki drew my attention to the publication on Tuesday of this paper: Multisensory Integration in Complete Unawareness. What Faivre et al report there is exactly the kind of phenomenon that Ryan Scott, Jason Samaha, Zoltan Dienes and I have been investigating. In fact, we have been aware of Faivre et al’s study and cite it in our paper (that is currently under review).

Their work is good, but ours goes further. Specifically, we show that:

  • a) Cross-modal associations can be learned when neither of the stimuli in the two modalities are consciously perceived (whereas the Faivre et al study relies on previously learned associations between consciously perceived stimuli).
  • b) Such learning can occur with non-linguistic stimuli.

Together, a) and b) really strengthen the case against accounts that assert that consciousness is required for multi-sensory integration (e.g., Global Workspace Theory). Some defenders of such theories might try to brush aside results like that of Faivre et al by revising their theories to say that consciousness is only required for higher-level cognition, such as learning; and/or by setting aside linguistic stimuli as a special case of (consciously) pre-learned cross-modal associations which can be exploited by unconscious processes to achieve the appearance of multi-sensory integration. Our results block both of these attempts to save (what we refer to as) integration theories.