Resource allocation and the attentional demands of letter encoding.

Abstract

The idea that familiar events can be encoded automatically has gained general acceptance in cognitive psychology since Posner and Boies (1971) first reported that reaction times to a secondary probe were not interfered with by letter encoding. More recently, Ogden, Martin, and Paap (1981) used a more valid control for estimating baseline probe performance and found secondary task interference, suggesting that letter encoding does require attentional resources. The present series of experiments began with the aim of evaluating Ogden et al's evidence against automaticity when the first letter was not terminated after a brief exposure, as was done in their study. In the first set of experiments we found evidence of encoding interference when the interval between the two letters was varied (50 to 1,000 msec), but this interference disappeared when there was a constant 1,000-msec interval between the letters. On the basis of these findings, we hypothesized that changes in the primary task (e.g., the exposure duration of the first letter or the interval between the two letters) may influence the momentary allocation of resources between the primary and secondary tasks. More specifically, we hypothesized that any momentary reduction in the resources demanded by the primary tasks results in a reallocation of resources to the secondary task, which in turn reduces the sensitivity of the secondary task to the demands of the primary task, that is, probe performance is moved into the data-limited region of processing (Norman & Bobrow, 1975). This idea was tested by reducing resource allocation to the probe task at the time of encoding by reducing the expectancy (i.e., the probability) of probes in the temporal proximity of the first letter. The results showed that this manipulation produced a large and significant increase in encoding interference. Moreover, when the intensity of the tone (probe) was decreased from 70 to 60 dB, the magnitude of encoding interference was further increased. In regard to the specific issue of automaticity, the findings suggest that encoding familiar events does require resources, which will result in secondary task interference given that the secondary task is in the resource-limited region of processing. More important, the findings suggest that the magnitude of secondary task interference is dependent on within-trial changes in resource allocation between the primary and secondary tasks. This possibility has general implications for dual-task methodology and the measurement of attentional demands.

Attention and Short-Term Memory in Normal Children, Aggressive Children, and Non-Aggressive Children with Attention-Deficit Disorder

“…Under such circumstances, the secondary task would fail to receive any allocation of attentional space (or it could be performed in the articulatory loop without causing decrements in executive functioning). Similar findings have been reported previously (Johnson, Forester, Calderwood, & Weisberger, 1983). It would be interesting to see the effects with more difficult secondary tasks.…”

Attentional costs of mental operations in young and old adults

“…The experimental tasks followed the paradigm developed by Posner and Boies (1971) and refined by subsequent investigators (Johnson et al, 1983). There were three task conditions, two single-task and one dual-task.…”

“…Subsequent studies (Comstock, 1973;Johnson, Forester, Calderwood, & Weisgerber, 1983;McLeod, 1978;Millar, 1975;Ogden, Martin, & Paap, 1980;Posner & Klein, 1973;Proctor & Fisicaro, 1977;Proctor & Proctor, 1979;Shwartz, 1976) have also demonstrated that matching and response selection are effortful, attention-demanding operations. However, these studies have not unequivocally demonstrated that letter encoding is an attention-free automatic operation.…”

“…However, these studies have not unequivocally demonstrated that letter encoding is an attention-free automatic operation. In fact, several of these studies have demonstrated that letter encoding does require attention when the first letter is only briefly exposed (Comstock, 1973;Ogden et al, 1980) or when the time interval between the two letters is occasionally very short (Johnson et al, 1983, Experiments 1 and 2). By contrast, letter encoding does appear to be automatic when the first letter is not briefly exposed or when the time interval between the two letters is constant and relatively long (Johnson et al,Experiments 3 and 4).…”

Dependence and independence in responding to double stimulation: A comparison of stop, change, and dual-task paradigms.

“…The results from the change paradigm also have important implications for studies that use responses to auditory probes to assess the resource demands of visual tasks (e.g., Britton & Tesser, 1982;Posner& Boies, 1971), especially when probe reaction times are compared with control conditions in which there is no overt response to the visual task (e.g., the no-letter "control" of Johnson, Forester, Calderwood, &Weisgerber, 1983, andof Ogden, Martin, &Paap, 1980). The present experiments suggest that those results may reflect response competition more than competition for more central resources, contrary to what the authors of those studies concluded.…”