Alzheimer’s disease (AD) patients underperform on a range of tasks requiring semantic processing, but it is unclear whether this impairment is due to a generalised loss of semantic knowledge or to issues in accessing and selecting such information from memory. The objective of this eye-tracking visual search study was to determine whether semantic expectancy mechanisms known to support object recognition in healthy adults are preserved in AD patients. Furthermore, as AD patients are often reported to be impaired in accessing information in extra-foveal vision, we investigated whether that was also the case in our study. Twenty AD patients and 20 age-matched controls searched for a target object among an array of distractors presented extra-foveally. The distractors were either semantically related or unrelated to the target (e.g., a car in an array with other vehicles or kitchen items). Results showed that semantically related objects were detected with more difficulty than semantically unrelated objects by both groups, but more markedly by the AD group. Participants looked earlier and for longer at the critical objects when these were semantically unrelated to the distractors. Our findings show that AD patients can process the semantics of objects and access it in extra-foveal vision. This suggests that their impairments in semantic processing may reflect difficulties in accessing semantic information rather than a generalised loss of semantic memory.

阿尔茨海默病 (AD) 患者在一系列需要语义处理的任务上表现不佳，但尚不清楚这种损害是由于语义知识的普遍丧失还是由于从记忆中访问和选择此类信息的问题。这项眼球追踪视觉搜索研究的目的是确定已知支持健康成人物体识别的语义预期机制是否在 AD 患者中保留。此外，据报道 AD 患者在获取中心凹外视力信息方面经常受到损害，我们调查了我们研究中是否也是这种情况。20 名 AD 患者和 20 名年龄匹配的对照者在中心凹外的一系列干扰物中搜索目标对象。干扰项要么在语义上与目标相关，要么与目标无关（例如，与其他车辆或厨房用品成排排列的汽车）。结果表明，与语义无关的对象相比，两组语义相关对象的检测难度更大，但 AD 组更显着。当关键对象在语义上与干扰物无关时，参与者会更早、更长时间地观察关键对象。我们的研究结果表明，AD 患者可以处理对象的语义并在中心凹外视觉中访问它。这表明他们在语义处理方面的损害可能反映了访问语义信息的困难，而不是语义记忆的普遍损失。当关键对象在语义上与干扰物无关时，参与者会更早、更长时间地观察关键对象。我们的研究结果表明，AD 患者可以处理对象的语义并在中心凹外视觉中访问它。这表明他们在语义处理方面的损害可能反映了访问语义信息的困难，而不是语义记忆的普遍损失。当关键对象在语义上与干扰物无关时，参与者会更早、更长时间地观察关键对象。我们的研究结果表明，AD 患者可以处理对象的语义并在中心凹外视觉中访问它。这表明他们在语义处理方面的损害可能反映了访问语义信息的困难，而不是语义记忆的普遍损失。