It has recently been suggested that a large proportion of the age-related influences on many measures of cognitive functioning is mediated through a single common factor. This hypothesis has been supported by the discovery that much of the age-related variance in different cognitive measures is shared, and is not distinct or independent. These earlier results were replicated in this project, and it was also discovered that measures of corrected visual acuity and processing speed share a very large proportion of the age-related variance in measures of working memory, associative learning, and concept identification. The apparent implication is that the common factor that appears to contribute to age-related differences in many cognitive measures is quite broad and may reflect a relatively general reduction in central nervous system functioning.

A new procedure for evaluating symbol comprehension, the phrase generation procedure, was assessed with 52 younger and 52 older adults. Participants generated as many phrases as came to mind when viewing 40 different safety symbols (hazard alerting, mandatory action, prohibition, and information symbols). Symbol familiarity was also assessed. Comprehension rates for both groups were lower than the 85% level recommended by the American National Standards Institute. Moreover, older participants' comprehension was significantly worse than younger participants', and the older adults also generated significantly fewer phrases. Generally, prohibition symbols were comprehended best and hazard alerting symbols worst. In addition, symbol familiarity was positively correlated with symbol comprehension. These findings indicate that important safety information depicted on signs and household products may be misunderstood if presented in symbolic form. Furthermore, certain types of symbols may be better understood (e.g., prohibition symbols) than other types (e.g., hazard alerting symbols) by both younger and older individuals. These findings signify the utility of the phrase generation procedure as a method for evaluating symbol comprehension, particularly when it is not possible or desirable to provide contextual information. Actual or potential applications of this research include using the phrase generation approach to identify poorly comprehended symbols, including identification of critical confusions that may arise when processing symbolic information.

Estimates of controlled and automatic processes hypothesized to underlie performance in a memory task and in an attention task were derived for 1 15 participants from 18 to 78 years of age using the process-dissociation procedure. Participants also performed speed and neuropsychological tests that were suspected to he negatively rclated to age. Process estimates showed good reliabilfu (from .76 to .98), and the qualintive distinction between processes t'as supported by the overall pattern of conelations an ong measures. However, only estimated automatic processes exhibited unique variance, as they were either weakly related or unrelated both to performance on the other tests and to each other. Estimates of the control processes, in contrast, shared considerable variance with measures from other tests, and there were no unique, or independent, age-related effects on these measures. The results highlight the need to distinguish between process purity and the uniqueness of age-related influences in accounting for age differe nc e s in c ognition.

Two experiments were conducted to determine if age affects comprehension for explicit and implied warning information and, if so, to reveal the nature of such effects. Experiment 1 measured younger (18-23 years) and older (65-75 years) adults' comprehension for real-world warnings via a verification test presented immediately after reading the warnings or after a delay. In Experiment 2, younger (18-22 years) and older (64-76 years) participants also read fabricated warnings that were inconsistent with real-world knowledge. In both experiments, older adults frequently failed to infer the correct hazard and safety information. The older adults also had trouble understanding warning information even when it was explicitly stated (when no inferences were required), especially when memory demands were high and product-specific knowledge could not be used. That many of the older adults did not understand commonly used product warnings indicates that the wording on many household products is not conducive to being understood by everyone who uses them. Actual or potential applications of this research include the recommendation that designers of product labels, warnings, and instructions should consider minimizing memory load and maximizing opportunities for knowledge application when designing consumer warnings.

Beliefs about warnings and habits associated with reading them were assessed for 863 individuals of various ages. Information gathered for various common household products included (a) how frequently people attend to warning information, (b) the degree of risk they believe is involved during product usage, and (c) how important they believe warnings are for different product types. Also assessed were perceived helpfulness and comprehension for symbols commonly found on product labels or on signs in the environment. Respondents 55 years and older reported reading product warnings more frequently than did younger adults, although they generally perceived warnings as less important. However, no overall age-related differences were found for perceived level of risk involved in using different product types. Although older adults generally perceived symbols to be very helpful when using a particular product, their comprehension levels were poorer than those of younger adults for half of the symbols. Overall, these data suggest that adults of all ages do read warnings on a variety of product types and that they believe warning information is important. This research illustrates the importance of including older adults in usability studies during the development of warning systems, given age-related effects may be associated with some aspects of the warning processing but not others.