Academic journal article Memory & Cognition

Effects of Instruction Presentation Mode in Comparative Judgments

Academic journal article Memory & Cognition

Effects of Instruction Presentation Mode in Comparative Judgments

Article excerpt

In each of two experiments, the comparative instructions in a symbolic comparison task were either varied randomly from trial to trial (mixed blocks) or left constant (pure blocks) within blocks of trials. In the first experiment, every stimulus was compared with every other stimulus. The symbolic distance effect (DE) was enhanced, and the semantic congruity effect (SCE) was significantly larger, when the instructions were randomized than when they were blocked. In a second experiment, each stimulus was paired with only one other stimulus. The SCE was again larger when instructions were randomized than when they were blocked. The enhanced SCE and DE with randomized instructions follow naturally from evidence accrual views of comparative judgments.

Any complete theory of the process of comparing either perceptual or remembered stimuli must provide an explanation for the semantic congruity effect (SCE). The SCE is characterized by an interaction between the particular comparative instruction required and the location of the stimulus pair to be discriminated on the underlying continuum. For example, as in the landmark psychophysical experiments of Audley and Wallis (1964) that brought the SCE to the attention of contemporary psychophysicists, the time to select the darker of two relatively dark lights is shorter than the time to select the brighter. Conversely, selection time of the brighter of two relatively bright lights is shorter than the selection time of the darker.

In Audley and Wallis's (1964) experiment, and in the replication and extension of Wallis and Audley with the pitch dimension, the comparative instructions (i.e., select the darker or select the lighter) were presented separately in counterbalanced blocks. In the large number of ensuing experiments, both in the strictly perceptual domains (e.g., Marschark & Paivio, 1981; Petrusic, 1992; Petrusic & Baranski, 1989) and in the voluminous literature with symbolic comparisons (for reviews, see, e.g., Banks, 1977; Leth-Steensen & Marley, 2000), both blocked and randomized modes of presentation of the instructions have been used. Curiously, it remains unclear whether instruction presentation mode affects the magnitude of the SCE.

Shaki and Algom (2002) have previously argued that contrasting conditions in which the instructions are blocked, as compared with when they are randomly intermixed over trials, should provide a strong test of LethSteensen and Marley's (2000) connectionist, instructional pathway interference model, because (for reasons to be detailed later) this model would almost certainly predict enhanced SCEs for randomized instructions, as compared with blocked ones. More generally, though, it is of interest to determine the theoretical implications that contrasting the SCE over instruction presentation modes have for most of the currently popular alternative theories of the SCE.

Another important and robust comparative judgment phenomenon is the symbolic distance effect (DE). This effect is characterized by longer response times (RTs) for comparisons of stimuli that are closer in magnitude than for comparisons of stimuli with larger differences in magnitude. Because DEs are invariably assumed to arise out of the same decision processes that give rise to the SCE (see Leth-Steensen & Marley, 2000, for a full discussion of theoretical accounts for the DE), it is also of interest to determine whether or not randomized and blocked instruction presentation modes have parallel effects on the sizes of both the symbolic DE and the SCE. Hence, in the present experiments, we directly examined these issues by comparing blocked versus randomized instruction presentation conditions in comparative judgments, using the classic Moyer (1973) stimuli of names of animals varying in size.




Sixteen Carleton University students participated in one 80-min session to satisfy course requirements. …

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