On the process of recognizing inverted words: does it rely only on orientation-invariant cues?

Following a demonstration by Parks (1983) of failure to notice the reflection of a letter of an inverted word, two experiments were conducted to test a hypothesis about the process of recognizing inverted words that is termed here invariant cues only (ICO)-a letter-by-letter identification process based only on orientation-invariant letter features. In Experiment 1, subjects were presented with whole strings-words and nonwords, either upright or inverted-in which either all the letters were normal or one of the letters was reflected, and they were asked to make lexical decisions. In Experiment 2, subjects made a reflection judgment about an upright or inverted letter within a string immediately after they had been presented with the other, nonreflected string letters, again either upright or inverted. The results do not support the ICO hypothesis: Lexical decisions were greatly affected by the reflection of a letter in upright and inverted stimuli alike. Reflection judgments were considerably facilitated by word context in the upright and the inverted modes alike. The results are accommodated better by the notion that recognition of disoriented words requires some correction used to restore orientation-sensitive features.