3. An awareness that they were being experimented upon seemed to be enough to alter workers's behavior by itself.

【分析】复合句。句子主干为 。An awareness...seemed to be enough to alter...。 that 引导同位语从句补充说明 awareness， 其中 they 指代后面的 workers。be enough to do “足以...”。

【译文】只要意识到她们在接受实验，这一意识本身似乎就足以改变工人们的行为。

4. Contrary to the description on record, no systematic evidence was found that levels of productivity were related to changes in lighting.

【分析】复合句。句子主干为 no systematic evidence was found...。 Contrary to 作句子状语，that 引导的从句作 evidence 的同位语，为避免句子头重脚轻，此同位语从句与先行词被谓语分离。

【译文】与有记载的描述相反，没有找到系统的证据来说明劳动生产率的水平与光照的变化有关。