Harnishfeger, Katherine Kipp

The relationship between the mental effort requirement
of strategy use and the development of an organizational
strategy was investigated. 1st, 3rd, and 5th graders were
assigned to one of four conditions reflecting the orthogonal
combination of organizational instructions (training vs free
recall) and item presentation (blocked by categories vs
random). During two free recall trials of a list of 16
words, subjects' mental effort expenditure was assessed by
measuring interference on a secondary task (finger tapping).
The older children recalled more items and were more
strategic than the younger children; however, there were no
differences in interference among the grades. Training
resulted in superior recall, clustering, and mental effort
expenditure; blocked presentation led to greater recall and
clustering, but not interference. It was suggested that the
activation of items in semantic memory and the use of
categorical organization to facilitate recall become more
efficient with age, resulting in superior performance by the
older children without corresponding increases in mental
effort.

Four experiments were conducted to examine developmental differences in inhibitory processing. Experiment 1 demonstrated increasing inhibitory efficiency with age in a Stroop-type task. First graders did not show a significant inhibition effect, which was shown by all older groups. With age, greater proportional decrements in response latency were found for Stroop tasks with an inhibition component than for a standard Stroop task. Experiment 2 contrasted cued-recall performance on an unrelated list with performance on a list of scrambled high-associate pairs. Kindergartners, second and fourth graders recalled less than adults, and more of their total output during recall was composed of inappropriate intrusions. Examination of interitem response latencies revealed that kindergartners' processing did not differentiate between inappropriate intrusions and correct responses, whereas older subjects distinguished between correct responses and all errors. In Experiment 3, subjects were read lists of words, were told to forget some of the words, and then were unexpectedly asked to recall the to-be-forgotten words. Adults and fifth graders who were told to forget were able to inhibit the pre-cue items, although the words were available in a recognition task. First graders were not able to inhibit activations of pre-cue items, and they did not show the standard directed-forgetting patterns of performance. Patterns of inhibition for third grade children fell between that of first and fifth graders. In Experiment 4, an intentional/incidental contrast was added to the directed-forgetting paradigm. This experiment replicated earlier work, finding directed-forgetting effects for both incidentally and intentionally learned words. Developmental changes in performance replicated those of Experiment 3. Latencies between consecutively recalled words were also examined. Subjects who were not told to forget words showed a processing advantage, in terms of faster latencies, for primacy items. When subjects were given the forget cue, their processing was slightly quicker for second list half items. In general, results were consistent with the inefficient inhibition hypothesis, suggesting that inhibitory processing becomes more efficient over the elementary school years. Implications for the limited mental resources model, and the inefficient inhibition hypothesis, were discussed.