Knowledge that Transforms

The large literature on incidental learning relies almost exclusively on laboratory experiments. Whenever researchers have attempted to demonstrate incidental learning of real-world regularities, they have typically failed to show learning. For example, it is well established that people do not learn regularities in everyday objects, such as the left-right orientation of faces on coins, despite a very large exposure to them. In this report, we examine this apparent contradiction. We argue that most studies exploring real-life incidental learning use tests that are not as sensitive to low-confidence information as those traditionally used in laboratory tasks. Using more sensitive measures, we show that it is possible to learn regularities from British and Japanese cultural life as a direct result of exposure to these regularities. Further, confidence measures suggest that although the information may be acquired incidentally, it can be expressed with and without concomitant awareness of that knowledge.

Genetic mechanisms have been proposed to explain the pervasive representation of right-handedness in humans, whereas random, nongenetic factors have been posited to explain the lack of population-level right-handedness in nonhuman primates. We report evidence that hand preferences in chimpanzees are heritable, even among related individuals raised in different environments. Furthermore, we report that the degree of heritability is modified by factors associated with developmental instability, notably, offspring parity. The data are interpreted to reconcile both genetic models for handedness and hypotheses suggesting that developmental instability influences variation in handedness.

Handbook of Research Methods in Social and Personality Psychology, edited by H.T. Reis and C.M. Judd. London: Cambridge University Press, 2000. 558 pp. Cloth, $69.95; paper, $34.95.

What are the memory processes that produce coherent representations of temporally discontinuous experiences? In this article, we describe the memory process of resonance, a process that provides renewed access to long-term memory information that is relevant to cues in working memory. Our experiments demonstrate c parallel waxing and waning of information as a function of relevance to a current episode, a pattern of accessibility of information that contributes to the achievement of continuity across experiences.

Practicing simple visual tasks induces substantial improvement. We investigated whether increased efficiency is accompanied by automaticity and immunity to across-task interference. We found that although practice speeds orientation feature detection, it does not abolish susceptibility to interference from introduction of concurrent central-letter identification, which takes priority. Yet following training with each task observers successfully managed to perform the tasks concurrently. The effectiveness of separate training implies that the role of improved intertask coordination in achieving concurrent performance was minor. Indeed, even when initial training was concurrent, improvement on the two tasks was sequential, and the higher-priority (central) task was learned first. However, automatic processing was not accomplished either, because increasing the difficulty of the higher-priority task interfered with performance of both tasks. What appears to be orchestrated posttraining performance is actually mainly an emergent property of speeded initial processes rather than either eliminated bottlenecks or improved central executive management.

We investigated the possibility that implicit memory, like explicit memory, can be disrupted by proactive interference. Participants first viewed a list of words, with nontargets in the first half of the list and targets in the second. Nontargets were either similar in structure (e.g., "ANALOGY") or unrelated (e.g., "URGENCY") to the targets (e.g., "ALLERGY"). After several filler tasks, participants completed an implicit fragment-completion test (e.g., "A_L_ _ GY") for the target items. Participants who viewed similar nontargets completed fewer fragments with target items and made more intrusions than did participants who viewed unrelated nontargets. Together with previous findings, these results suggest that similar nontargets can compete with target items to produce interference in implicit memory.

A wealth of research has shown that observers can bias visual processing toward specific locations, but the role of object-based selection is less clear In support of object-based selection, previous research has shown that when two objects are presented simultaneously, observers are better at reporting two attributes from one of the objects than one attribute from each object. However there has been controversy over whether this effect is best explained by object-based selection or spatial selection. Our work suggests that there are two separate components of selection in this task: (Ca) a spatial component that is observed when the relevant targets are cued for observers before the onset of the stimulus display and (b) an object-based component that can still be observed when the first component has been eliminated. The latter effect replicates the initial evidence in favor of object-based selection, and can be demonstrated even when the relevant targets are cued after the offset of the target stimuli.

This study develops a new theory of long-term retrograde amnesia that encompasses episodic and semantic memory, including word knowledge. Under the theory, retrograde amnesia in both normal individuals and hippocampal amnesics reflects transmission deficits caused by aging, nonrecent use of connections, and infrequent use of connections over the life span. However, transmission deficits cause severe and irreversible retrograde amnesia only in amnesics who (unlike normal persons) cannot readily form new connections to replace nonfunctioning ones. The results of this study are consistent with this theory: For low-frequency but not high-frequency words, a famous "hippocampal amnesic" (H.M.) at age 71 performed worse than memory-normal control participants in a lexical decision experiment and a meaning-definition task (e.g., What does squander mean?). Also as predicted, H.M.'s lexical decision performance declined dramatically between ages 57 and 71 for low-frequency words, but was age-invariant for high-frequency words.

Many common activities rely on spatial knowledge acquired from nonvisual modalities. We investigated the nature of this knowledge by having people look at a collection of objects on a desktop and manually reconstruct their arrangement, without vision, as though the display had been rotated by 0 degrees 45 degrees 90 degrees 135 degrees or 180 degrees relative to the view they could see. Performance on several measures of visual-spatial memory showed that participants had better visual memory for the view they had manually reconstructed than for the view they had studied visually for several minutes. These findings provide compelling new evidence that visual-spatial knowledge of very high fidelity can be acquired from nonvisual modalities, and reveal how, visual and nonvisual spatial information may even be confused in the brain.

A critical step toward object recognition is the segmentation of a scene into relevant regions. One of the most important cues for segmentation is that of common fate: Elements that move together are grouped together Here we describe a new instantiation of common fate, in which elements move together not through physical space, but through luminance space. Experiment I shows that when elements of a scene become brighter together or darker together, observers group those elements together Experiments 2 and 3 show that this effect is not due to the availability of fixed luminance differences between target and background regions, but requires common changes within each region in the direction of luminance over time. The effect is differentiated from the recently discovered grouping cue of temporal synchrony, and is considered instead to be an extension of Wertheimer's original grouping factor of common fate. Common fate for luminance, or generalized common fate, is an extremely strong cue for the segmentation of a scene, yielding a tremendous advantage over grouping by fixed luminance cues.