Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany.
Faculty for Biology, University of Freiburg, Freiburg im Breisgau, Germany.
Sci Rep. 2024 Oct 18;14(1):24486. doi: 10.1038/s41598-024-74693-x.
During visual imagination, a perceptual representation is activated in the absence of sensory input. This is sometimes described as seeing with the mind's eye. A number of physiological studies indicate that the brain uses more or less the same neural resources for visual perception of sensory information and visual imagination. The intensity of visual imagination is typically assessed with questionnaires, while more objective measures are missing. Aim of the present study was, to test a new experimental paradigm that may allow to objectively quantify imagination. For this, we used priming and adaptation effects during observation of ambiguous figures. Our perception of an ambiguous stimulus is unstable and alternates spontaneously between two possible interpretations. If we first observe an unambiguous stimulus variant (the conditioning stimulus), the subsequently presented ambiguous stimulus can either be perceived in the same way as the test stimulus (priming effect) or in the opposite way (adaptation effect) as a function of the conditioning time. We tested for these conditioning effects (priming and adaptation) using an ambiguous Necker Cube and an ambiguous Letter /Number stimulus as test stimuli and unambiguous variants thereof as conditioning stimuli. In a second experimental condition, we tested whether the previous imagination of an unambiguous conditioning stimulus variant - instead of its observation - can have similar conditioning effects on the subsequent test stimulus. We found no systematic conditioning effect on the group level, neither for the two stimulus types (Necker Cube stimuli and Letter /Number stimuli) nor for the two conditions (Real and Imaginary). However, significant correlations between effects of Real and Imaginary Condition were observed for both stimulus types. The absence of conditioning effects at the group level may be explained by using only one conditioning time, which may fit with individual priming and adaptation constants of some of our participants but not of others. Our strong correlation results indicate that observers with clear conditioning effects have about the same type (priming or adaptation) and intensity of imaginary conditioning effects. As a consequence, not only past perceptual experiences but also past imaginations can influence our current percepts. This is further confirmation that the mechanisms underlying perception and imagination are similar. Our post-hoc qualitative observations from three self-defined aphantasic observers indicate that our paradigm may be a promising objective measure to identify aphantasia.
在视觉想象中，即使没有感官输入，也会激活知觉表象。这有时被描述为用“心灵之眼”看。许多生理学研究表明，大脑在感知感官信息和视觉想象时使用的神经资源或多或少是相同的。视觉想象的强度通常通过问卷进行评估，而缺乏更客观的测量方法。本研究的目的是测试一种新的实验范式，该范式可能允许客观地量化想象。为此，我们在观察模糊图形时使用了启动和适应效应。我们对模糊刺激的感知是不稳定的，会自发地在两种可能的解释之间交替。如果我们先观察到一个明确的刺激变体（条件刺激），那么随后呈现的模糊刺激可以以与测试刺激相同的方式被感知（启动效应），或者以相反的方式被感知（适应效应），这取决于条件时间。我们使用模糊的 Necker 立方体和模糊的字母/数字刺激作为测试刺激，以及它们的明确变体作为条件刺激，来测试这些条件效应（启动和适应）。在第二个实验条件下，我们测试了先前对明确条件刺激变体的想象 - 而不是观察 - 是否可以对随后的测试刺激产生类似的条件效应。我们在组水平上没有发现系统的条件效应，无论是对于两种刺激类型（Necker 立方体刺激和字母/数字刺激）还是对于两种条件（真实和想象）。然而，对于两种刺激类型，我们观察到真实和想象条件之间的效应存在显著相关性。在组水平上没有条件效应可能是由于只使用了一个条件时间，这可能与我们一些参与者的个体启动和适应常数相匹配，但与其他人的不匹配。我们的强相关结果表明，具有明显条件效应的观察者具有大致相同类型（启动或适应）和强度的想象条件效应。因此，不仅是过去的感知经验，还有过去的想象，都会影响我们当前的感知。这进一步证实了感知和想象的机制是相似的。我们从三个自我定义的失认症观察者的事后定性观察表明，我们的范式可能是一种有前途的客观测量方法，可以识别失认症。
