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In the negative compatibility effect (NCE) a masked prime arrow, pointing left or right, is followed by an unmasked (visible) target arrow. The task is to press the left or right switch corresponding to the visible arrow. Surprisingly, reaction time is longer (slowed) when the prime and target indicate the same, rather than different, responses. By contrast, the effect of an unmasked prime is positive-opposite to the NCE. This indicates that the NCE is not attributable to incomplete masking; to the extent that the prime is visible, the NCE would be reduced by this positive influence. Thus, the NCE appears to result from unconscious processing of the prime and, in that sense, may be a form of subliminal perception. Additional findings show that the NCE is due to inhibition of a response code, that it is automatic in that it occurs even if the information in the prime and target could be ignored, and that it also influences response selection.

Four experiments tested the necessity of extended practice in producing automaticity in an alphabet-arithmetic task in which subjects verified equations of the form A + 2 = C, asking whether C was two letters down the alphabet from A. Experiment 1 trained subjects on 40 alphabet-arithmetic facts for 12 sessions, demonstrating that extended practice was sufficient to produce automaticity. Experiment 2 produced the same degree of automaticity in a single session by having subjects rote memorize 6 facts, suggesting that extended practice is not necessary. Experiments 3 and 4 explored procedural differences between Experiments 1 and 2 to determine what was responsible for the large difference in the time required to develop automaticity. Experiment 3 compared learning rates with different numbers of facts (6, 12. and 18), and found learning rate to depend on the number of presentations of individual items, not on the number of items to be learned. Experiment 4 compared learning by performing the task (as in Experiment 1) with learning by remembering the facts (as in Experiment 2) and found no important differences between them. The results of all 4 experiments cannot be predicted by approaches that define automaticity in terms of resources or by listing properties, although they are readily predictable from theories that assume memory retrieval is the process that underlies automaticity. Is extended practice necessary to produce automaticity? Can automaticity to be produced without it? Extended practice is certainly sufficient. Many of the properties of automaticity can be produced by extended practice (e.g., Logan, 1978; Shiffrin & Schneider, 1977) or by using materials such as familiar words that have a history of extended practice outside the laboratory (e.g., Neely, 1977). However, sufficiency does not imply necessity. Existing data provide no answer. Common theoretical approaches to automaticity provide no answer either. Approaches that define atuomaticity in terms of manifest properties, such as speed, effortlessness, and autonomy (property-list approaches), are stipulative or descriptive but not predictive (e.g., Hasher & Zacks, 1979; LaBerge & Samuels, 1974; Shiffrin & Schneider, 1977). They provide no underlying mechanism from which predictions about the properties of automaticity or necessity of extended practice can be deduced.

Reaction time (RT) prior to speech articulation increased as a function of response complexity. The RT findings formed 2 patterns, each of which was a different Response Complexity x Paradigm (choice RT vs. simple RT) interaction. That result extends previous findings from manual button-pressing tasks (S. T. Klapp, 1995) to a different action modality. Two different types of response programming, INT and SEQ, are assumed in the interpretation. Whereas INT can be identified with response programming within a word, SEQ fits a different interpretation related to timing of onsets of speech units. A critical assumption is that a long response is represented as a sequence of chunks; that organization is subject to manipulation. New findings suggest some modifications of the previous theory.

A. Lleras and J. T. Enns demonstrated a negative influence of a masked arrow that is attributable to the perceptual interaction between the arrow and the mask when these have properties in common (in this case diagonal lines). Although the present analysis is in agreement that this type of perceptual interaction can occur, it also demonstrates that this is not the only way a masked arrow can produce a negative influence. The most critical finding is that a negative influence occurred even when the arrow and mask did not share the common properties that would be needed for this type of perceptual interaction. This illustrates the version of the negative compatibility effect that was studied by S. T. Klapp and L. B. Hinkley (2002) and others.