Harris J P, Fahle M
Department of Psychology, University of Reading, Whiteknights, England.
Vision Res. 1995 Jan;35(1):51-8. doi: 10.1016/0042-6989(94)e0082-v.
By detection of spatial offsets is meant the ability to indicate whether or not a given (vernier) stimulus has a spatial offset. Discrimination, on the other hand, implies that the direction of offset has been correctly identified. We compared vernier thresholds for these two tasks and found a consistent difference by a factor of around 2 in favour of discrimination. This is to say that observers are able to correctly indicate the direction of offsets that are too small to be reliably detected by the same observers. This apparent paradox can be explained on the assumptions that one single, bipolar mechanism is involved in both tasks, and that observers use a direction selective cue such as the orientation difference of the implicit lines through the vernier stimuli. The implications for estimates of the sensitivity of hyperacuity are discussed.
通过空间偏移检测是指能够指示给定（游标）刺激是否存在空间偏移的能力。另一方面，辨别意味着偏移方向已被正确识别。我们比较了这两项任务的游标阈值，发现辨别任务的阈值始终比检测任务小约2倍。也就是说，观察者能够正确指示偏移方向，而这些偏移太小以至于同一观察者无法可靠地检测到。这种明显的悖论可以基于以下假设来解释：这两项任务都涉及单一的双极机制，并且观察者使用方向选择性线索，例如通过游标刺激的隐线的方向差异。文中还讨论了对超敏锐度敏感性估计的影响。
