This study is concerned with recent claims that subjective measures ofword frequency are more suitable than are standard word frequency counts as indices of actual frequency of word encounter. A multiple regression study is reported, which shows that the major predictor offamiliarity ratings is word learning age. Objective measures of spoken and written word frequency made independent contributions to the variance. It is concluded that rated familiarity is not an appropriate substitute for objective frequency measures. A multiple regression study of word naming latency is reported, and shows that rated word learning age is a better predictor ofword naming latency than are spoken word frequency, written word frequency, rated familiarity, and other variables. Possible theoretical explanations for age-of-acquisition effects are discussed and it is concluded that early-learned words have a more complete representation in a phonological output lexicon. This conclusion is related to relevant developmental literature.

J. Pratt and R.A. Abrams (1995) reported that the inhibition of return of attention is found only for the most recently attended of 2 cued locations. This study does not dispute their findings, but suggests that a more ecologically valid experiment would have more than 2 possible target locations. Twelve male students participated in an experiment in which the target may occur in 1 of 4 possible locations, after 3 of those locations have been cued exogenously in sequence. Inhibition of return was found for each of the cued locations. This result suggests that inhibition may be an important mechanism for aiding visual search in complex environments.

Wereport two experiments that examine the effects of practice on object-based, location-based, and static-display inhibition of return (IOR). The results are clear: All three effects get smaller with practice. These findings are at odds with the results of Muller and von Miihlenen (1996), who failed to observe object-based IORand detected no effect of practice on static-display IOR. However,their subjects were more practiced than ours prior to data collection. Wesuggest, therefore, that the reducing effect of practice on IOR might have occurred in their unrecorded practice sessions. Wealso discuss a twoprocess model in which IORis seen as the net effect of underlying inhibitory and excitatory processes. In such models (e.g., Solomon & Corbit, 1974),practice often results in a reduction of the net effect of the two processes.In what has become a classic chapter, Posner and Cohen (1984) reported the results of a seemingly very simple attentional cuing paradigm. In one version of the task, three horizontally aligned boxes appeared on the screen (see Figure lA). Either the left or the right peripheral box was then cued by a briefbrightening of its outline ( Figure IB). Shortly afterwards, the central box was cued in the same manner ( Figure 1C). On some trials, a target appeared in either the left or the right peripheral box ( Figure ID): Half of the targets appeared in the same box as the peripheral cue, and half appeared in the uncued box. The stimulus onset asynchrony (SOA) from peripheral cue to target was either 100 or 650 msec. On "catch" trials, no target appeared. The task was to indicate detection ofthe target by pressing a key as quickly as possible.The results of this experiment were very clear: Responses to cued targets were faster than responses to uncued targets at the shorter SOA, but were slower at the longer SOA (see Figure 2). Other experiments reported by Posner and Cohen (1984) confirmed this result, and indicated that responding to cued targets is facilitated for about 150 msec after presentation of the cue and impaired for SOAs between 300 and 1,500 msec.Posner, Rafal, Choate, and Vaughan (1985) referred to the slowed responding in the cued condition as inhibition Some ofthis research was funded by Grant AP92-24228372 awarded to the second author by the Spanish Ministerio de Educaci6n y Ciencia. We thank Steve Tipper, Ray Klein, Hermann Muller, and an anonymous reviewer for commenting on an earlier draft of this article. Correspondence should be addressed to either 8. Weaver or 1.Lupiafiez. B. Weaver is now at the Father Sean O'Sullivan Research Centre, 50 Charlton Avenue West, Hamilton, ON, L8N 4A6, Canada (e-mail: bw 1960@yahoo. corn). 1. Lupiaiiez is now at Deparlamento de Psicologia Experimental y Fisiologia del Cornportamiento, Facultad de Psicologia, Campus Universitario de Cartuja, Universidad de Granada, l8071-Granada, Spain (e-mail: jlupiane@platon.ugr.es).ofreturn (IOR). This name for the effect gives a good clue as to Posner and Cohen's (1984) theoretical interpretation of it. They s...

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The cognitive and subjective effects of sub-anaesthetic doses of ketamine on healthy volunteers were examined. Twelve healthy volunteers received 25 mg ketamine, 10 mg ketamine and saline placebo, i.m. in a double-blind, Latin square design. A cognitive, perceptual and self-report test battery was administered over 45 min. The order of tests was rotated to control for timing effects. Ketamine (25 mg) significantly affected verbal learning and memory, parallel visual search, some measures of psychomotor performance, measures of arousal, subjective mood ratings and visual perception. Measures of attention and frontal lobe functioning were relatively unaffected. Thus, low doses of ketamine had selective, dose-related effects on memory, perceptual and psychomotor functions. The disruption of memory and perceptual processes may help to explain the unique subjective state induced by ketamine.