The effects of isolation and generation on memory for order were investigated in 4 experiments. Experiments 1 and 2 examined the effect of isolation on order retention. Previous investigations in this area have yielded equivocal results. Experiments 1 and 2 revealed that isolation enhances memory for order: Isolated items were repositioned more accurately than comparable items in control lists. Experiments 3 and 4 investigated the effect of generation on order retention. These experiments revealed that generation can enhance, disrupt, or have no effect on memory for order, depending on the relative number of generated items appearing within a list. Implications of these results for general theoretical accounts of isolation effects in memory are discussed. A simplified version of the feature model (J. S. Nairne, 1990) is shown to provide a general account of isolation effects.

No abstract

The phonological similarity effect-poor retention of order for lists of similar-sounding items-is a benchmark finding in the short-term memory literature. In our first two experiments, we show that the effect actually reverses following relatively brief periods of distraction, yielding better order retention for similar than for dissimilar lists, provided that different items are used on every trial. In Experiment 3, the same items were used on every trial and similar lists produced poorer performance across all three retention intervals. The results are interpreted from a general discrimination framework: Items are viewed as occupying positions in a multidimensional space defined by list and within-list dimensions.In immediate serial recall, lists composed of similarsounding items "ire typically remembered less well than lists of dissimilar items (Baddeley, 1966;Conrad, 1964;Conrad & Hull, 1964;Hintzman, 1967). Increasing the phonological similarity among the members of a to-berecalled set results in more omission errors at test, as well as more item-to-item transpositions in the output order (Coltheart, 1993;Conrad, 1965;Hintzman, 1965). The disruptive effects of phonological similarity are robust and have been replicated with a wide variety of experimental designs and materials, including the use of letters (Conrad, 1964), words (Baddeley, 1966), pictures (Hitch & Halliday, 1983), visual presentation (Baddeley, 1968, auditory presentation (Longoni, Richardson, & Aiello, 1993;Posner & Konick, 1966), and RSVP (Coltheart & Langdon, 1998). It is fair to say that the phonological similarity effect has achieved the status of a "benchmark" finding in the immediate memory literature, and most theories of short-term memory include mechanisms that are specifically designed to account for the phenomenon (e.g., Baddeley, 1986Baddeley, , 1992Burgess & Hitch, 1992;Drewnowski, 1980;Nairne, 1990a;Schweickert, Guentert, & Hersberger, 1990;Shiffrin & Cook, 1978).Nairne's (1990a) feature model, for example, is a member of a class of models that places the locus ofthe effect primarily at the point ofretrieval, where the memory trace is interpreted or "deblurred," Confusions are thought to arise when degraded primary memory traces are compared with candidate members of a secondary memory search set. If list items sound similar (i.e., they share common vowel and/or consonant sounds), it is assumed that their mnemonic representations contain many overlapping features. Feature overlap, in tum, means that the representation of a given item in the sequence is apt to be confused with other list items, leading to incorrect trace interpretations at retrieval. Models that place the locus ofsuch simCorrespondence should be addressed to 1. S. Nairne, Department of Psychological Sciences, Purdue University, West Lafayette, IN 47907-1364 (e-mail: nairne@psych.purdue.edu). 45ilarity effects during the trace interpretation stage have been shown to mimic the empirical data quite well (Nairne, 1990a; see also Lewandowsky & Murdock, 1989).The phon...

Many current models of memory are specified with enough detail to make predictions about patterns of errors in memory tasks. However, there are often not enough empirical data available to test these predictions. We report two experiments that examine the relative frequency of fill-in and infill errors. In immediate serial recall tasks, subjects sometimes incorrectly recall item N too soon, placing it in position N-1. The error of interest is which item is recalled after this initial mistake. A fill-in error is the tendency to recall item N-1 next, whereas an infill error is the tendency to recall item N+1 next. Both experiments reveal more fill-in than infill errors, not only overall but at each possible error location throughout the list. The overall ratio is approximately 2:1. We conclude that none of the currently existing models adequately accounts for fill-in and infill errors.

Mononuclear [Ir{ArNC(NR(2))NAr}(C(8)H(12))] complexes (where R = Me or Et; Ar = Ph, 4-MeC(6)H(4), or 2,6-Me(2)C(6)H(3); and C(8)H(12) = 1,5-cyclooctadiene) were synthesized from the neutral N,N-dialkyl-N',N''-diarylguanidines via deprotonation and transmetalation. As confirmed by single-crystal structure determinations, the guanidinato(1-) ligands coordinate the low-valent d(8) Ir(I) center in an N,N'-chelating binding mode, and the (13)C NMR chemical shifts of the alkene carbon atoms establish that these ligands function as stronger donors than related monoanionic, bidentate nitrogen-based ligands. In the reactions of the complexes with O(2), the observed reactivity trends correlate with the electronic and steric influences of the substituents of the guanidinato ligands.