Empirical evaluation and justification of methodologies in psychological science.

The purpose of this article is to describe a relatively new movement in the history and philosophy of science, naturalism, a form of pragmatism emphasizing that methodological principles are empirical statements. Thus, methodological principles must be evaluated and justified on the same basis as other empirical statements. On this view, methodological statements may be less secure than the specific scientific theories to which they give rise. The authors examined the feasibility of a naturalistic approach to methodology using logical and historical analysis and by contrasting theories that predict new facts versus theories that explain already known facts. They provide examples of how differences over methodological issues in psychology and in science generally may be resolved using a naturalistic, or empirical, approach.

Determinants of right-left and top-bottom prevalence for two-dimensional spatial compatibility.

When stimulus and response sets vary along horizontal and vertical dimensions, the horizontal dimension is more dominant than the vertical one, an effect called right-left prevalence. Three accounts have been proposed that attribute the effect to a reduced ability to code vertical locations when horizontal codes are also present, the use of right-left effectors, or a difference in salience of the 2 dimensions. The accounts differ in terms of whether the ability to code and process the 2 dimensions is of limited capacity and whether the prevalence effect is a consequence of the effectors used for responding. The authors report 4 experiments that evaluated these issues. Results indicate that use of right-left effectors is important to the right-left prevalence effect because it increases the salience of the horizontal dimension. However, a top-bottom prevalence effect can be obtained if the vertical dimension is made more salient.

The up-right/down-left advantage occurs for both participant- and computer-paced conditions: an empirical observation on Adam, Boon, Paas, and Umiltà (1998).

When up and down stimuli are mapped to left and right keypresses or "left" and "right" vocalizations in a 2-choice reaction task, performance is often better with the up-right/down-left mapping than with the opposite mapping. J. J. Adam, B. Boon, F. G. W. C. Paas, and C. Umiltà (1998) presented evidence that the up-right/down-left advantage is obtained when trials are participant paced but not when they are computer paced. In all, 3 experiments are reported that show no difference in magnitude of the up-right/down-left advantage between computer-paced and participant-paced conditions. The advantage was eliminated, however, in Experiment 3 when a response deadline was imposed. Response speed, rather than participant or computer pacing of trials, is crucial.

Effect of an initiating action on the up-right/down-left advantage for vertically arrayed stimuli and horizontally arrayed responses.

When up and down stimuli are mapped to left and right keypresses or "left" and "right" vocalizations in a 2-choice reaction task, performance is often better with the up-right/down-left mapping than with the opposite mapping. This study investigated whether performance is influenced by the type of initiating action. In all, 4 experiments showed the up-right/down-left advantage to be reduced when the participant's initiating action was a left response compared with when it was a right response. This reduction occurred when the initiating action and response were both keypresses, both were spoken location names, and one was a spoken location name and the other a keypress. The results are consistent with the view that the up-right/down-left advantage is due to asymmetry in coding the alternatives on each dimension, and a distinction between categorical and coordinate spatial codes seems to provide the best explanation of the advantage.

Influence of irrelevant information on human performance: effects of S-R association strength and relative timing.

Six experiments examined effects of stimulus-response (S-R) association strength and relative timing on the magnitude of consistency effects for irrelevant information in Stroop-like tasks. Keypresses were made to two-dimensional stimuli (a colour or location word surrounded by a coloured rectangle or arrow), with the irrelevant information presented simultaneously with or prior to the relevant information. With simultaneous presentation, irrelevant information affected performance regardless of whether its S-R association was weak or strong, if the relevant S-R association was weak (e.g., colour word to keypress). However, a weak irrelevant S-R association (location word to keypress) had little effect when paired with a strong relevant S-R association (arrow direction to keypress), except when the stimulus onset asynchrony (SOA) between the irrelevant and relevant information was 300 ms. When the relevant information was colour, the effect of an irrelevant colour word persisted at a 500-ms SOA but that of an irrelevant physical colour did not, reflecting different decay functions for irrelevant verbal and non-verbal information. The persisting effect of an irrelevant colour word was reduced by articulatory suppression and eliminated at extended SOAs of 3 s. The results indicate that whether the consistency effect patterns are symmetric or asymmetric is determined by the relative strengths of the relevant and irrelevant S-R associations, as specified by the criteria of conceptual and mode similarity. The magnitude of the consistency effect is also a function of the temporal overlap of the resulting response activation, which is determined primarily by mode similarity.

Mixing incompatible mapped location-relevant trials with location-irrelevant trials: effects of stimulus mode on the reverse Simon effect.

When location-relevant trials with an incompatible spatial stimulus-response mapping are mixed with location-irrelevant trials, responses on the latter trials are faster when stimulus and response locations do not correspond than when they do. Experiments 1 and 2 showed that this reverse "Simon effect" also occurs when the location information is presented verbally or symbolically on both location-relevant and location-irrelevant trials. The reversal was absent, however, in conditions of Experiments 1-3 in which the mode of presentation was different on the location-relevant trials than on the location-irrelevant trials. Experiment 4 demonstrated that differences in physical characteristics between the location-relevant and location-irrelevant stimuli were not sufficient to eliminate the reverse Simon effect. These findings imply that the short-term associations between stimulus location information and responses defined for the location-relevant task are relatively mode specific.

Vertical versus horizontal spatial compatibility: right-left prevalence with bimanual responses.

For two-choice tasks in which stimulus and response locations vary along horizontal and vertical dimensions, the spatial compatibility effect is often stronger on the horizontal than vertical dimension. Umiltà and Nicoletti [(1990) Spatial stimulus-response compatibility (pp. 89-116). Amsterdam: North-Holland] attributed this right-left prevalence effect to an inability to code vertical location when horizontal codes are present simultaneously. Hommel [(1996) Perception & Psychophysics, 43, 102-110] suggested instead that it reflects a voluntary strategy. This study reports four experiments that examine this issue. Experiment 1 was a conceptual replication of Hommel's Experiment 1, with responses made on a numeric key-pad and subjects instructed in terms of the vertical or horizontal dimension. The results replicated Hommel's findings that showed a right-left advantage with horizontal instructions; however, with vertical instructions, we found a benefit of vertical compatibility alone that he did not. This benefit for vertical compatibility alone was eliminated in Experiment 2 using a varied practice schedule similar to that used by Hommel. Experiment 3 showed right-left prevalence and a benefit of vertical compatibility alone, even with varied practice and vertical instructions, when subjects responded on perpendicularly arranged hand-grips. These benefits were eliminated in Experiment 4 using Hommel's method of urging subjects to respond only in terms of the instructed dimension. With bimanual responses, right-left prevalence is a robust phenomenon that is evident when comparing across vertical and horizontal instructions and, when the right-left distinction is relatively salient, within the vertical instructions condition alone.

Mixing location-relevant and location-irrelevant choice-reaction tasks: influences of location mapping on the Simon effect.

The Simon effect refers to the finding that reaction times are faster when stimulus and response locations correspond than when they do not in tasks where stimulus location is defined as irrelevant. The authors examined the Simon effect for situations in which location-irrelevant trials were intermixed with trials for which stimulus location was relevant. Compatible mapping of the location-relevant trials enhanced the Simon effect relative to an unmixed condition, whereas incompatible mapping reversed the Simon effect. The reversal with incompatible mapping remained evident when task uncertainty was removed by use of a precue and was larger than the reversed effect produced by making incongruent trials more frequent than congruent trials. This result suggests that both attentional biases and task-defined associations contribute to the reversal of the Simon effect.

Laudan's normative naturalism: a useful philosophy of science for psychology.

Logical positivism, widely regarded as the received epistemology of psychology in the first half of the 20th century, was supplanted in the 1960s by various postpositivistic, relativistic philosophies of science, most notably that of Kuhn. Recently, Laudan, a major figure in the philosophy of science, developed a novel approach called normative naturalism that provides an alternative to positivism and relativism. His central thesis is that the two are not always on opposite ends of a continuum but rather have many assumptions in common. This article brings Laudan's important views to the attention of psychologists and describes some of the unique implications of these views for the conduct of research and theory in psychology. These implications, which follow from a number of closely reasoned pragmatic arguments, include more realistic and appropriate evaluation of theory and methodology than has been suggested by logical positivism or relativism.

Auditory stimulus-response compatibility: is there a contribution of stimulus-hand correspondence?

Simon, Hinrichs, and Craft found that when subjects responded to a tone in the left or right ear with a left or right keypress, both ear-response-location correspondence and ear-hand correspondence affected reaction time. This outcome is in contrast to results obtained for auditory and visual Simon tasks (i.e., tasks in which stimulus location is irrelevant) as well as results obtained in visual stimulus-response (S-R) compatibility studies, which show only an effect of spatial S-R correspondence. Experiment 1 was a replication of Simon et al.'s experiment in which spatial mapping and hand placement (uncrossed, crossed) were varied. The results were inconsistent with those of Simon et al., showing no ear-hand compatibility effect. Experiment 2 was a second replication with an additional condition examined in which the stimuli were visual locations. The results showed no contribution of stimulus-hand correspondence for either auditory or visual stimuli. Experiment 3 was a replication of another experiment by Simon et al. in which tone pitch was relevant and tone location irrelevant. Like Simon et al.'s data, our results showed no indication that stimulus-hand correspondence is a significant factor. Overall, our results imply that regardless of whether tone location is relevant or irrelevant, ear-response-location correspondence is the only factor that contributes to S-R compatibility in auditory two-choice reaction tasks.

Multiple spatial correspondence effects on dual-task performance.

Three dual-task experiments were conducted to examine whether the underadditive interaction of the Simon effect and stimulus onset asynchrony (SOA) on Task 2 performance is due to decay. The experiments tested whether the reverse Simon effect obtained with an incompatible stimulus-response (S-R) mapping would show an overadditive interaction with SOA, as predicted by R. De Jong, C.-C. Liang, and E. Lauber's (1994) dual-process model. Tone or letter identification tasks with vocal or keypress responses were used as Task 1. Task 2 was keypresses to arrow direction (or letter identity in Experiment 1). For all experiments, the normal Simon effect showed an underadditive interaction with SOA, but the reverse Simon effect did not show an overadditive interaction. The results imply that the dual-process model is not applicable to the dual-task context. Multiple correspondence effects across tasks implicate an explanation in terms of automatic S-R translation.

A comparison of two response time models applied to perceptual matching.

Two models, a Poisson race model and a diffusion model, are fit to data from a perceptual matching task. In each model, information about the similarity or the difference between two stimuli accumulates toward thresholds for either response. Stimulus variables are assumed to influence the rate at which information accumulates, and response variables are assumed to influence the level of the response thresholds. Three experiments were conducted to assess the performance of each model. In Experiment 1, observers performed under different response deadlines; in Experiment 2, response bias was manipulated by changing the relative frequency of same and different stimuli. In Experiment 3, stimulus pairs were presented at three eccentricities: foveal, parafoveal, and peripheral. We examined whether the race and diffusion models could fit the response time and accuracy data through changes only in response parameters (for Experiments 1 and 2) or stimulus parameters (for Experiment 3). Comparisons between the two models suggest that the race model, which has not been studied extensively, can account for perceptual matching data at least as well as the diffusion model. Furthermore, without the constraints on the parameters provided by the experimental conditions, the diffusion and the race models are indistinguishable. This finding emphasizes the importance of fitting models across several conditions and imposing logical psychological constraints on the parameters of models.

Deconstructing Marilyn: robust effects of face contexts on stimulus-response compatibility.

Hommel and Lippa (1995) found a left-right spatial compatibility effect with respect to a background context of Marilyn Monroe's face, rotated 90 degrees clockwise or counterclockwise from upright, when subjects responded to up or down stimuli by pressing a left or a right key. They interpreted their results as providing evidence for object-based coding of stimulus location. We conducted four experiments in order to evaluate the reliability of this face context effect, to control for possible artifacts and evaluate alternative explanations, and to establish generalizability to other face contexts. This was accomplished by using not only the original photograph, but also a mirror-reversed image, chimeric faces composed from the left or the right sides of the original photograph, an outline drawing face, and a circle with markings for facial features. Our results were much stronger than those of Hommel and Lippa, and the face context effect was found for all of the face variations. Our experiments also provided evidence to suggest that asymmetric coding of the up and down locations contributes to performance in the face context as well.

Processing irrelevant location information: practice and transfer effects in choice-reaction tasks.

Left or right keypresses to a relevant stimulus dimension are faster when the stimulus location, although irrelevant, corresponds with that of the response than when it does not. This phenomenon, called the Simon effect, persisted across 1,800 trials of practice, although its magnitude was reduced. Practice with the relevant stimulus dimension presented at a centered location had little influence on the magnitude of the Simon effect when irrelevant location was varied subsequently, and practice with location irrelevant prior to performing with location relevant slowed responses. After practice responding to stimulus location with an incompatible spatial mapping, the Simon effect was reversed (i.e., responses were slower when stimulus location corresponded with response location) when location was made irrelevant. When the response keys were labeled according to the relevant stimulus dimension (the Hedge and Marsh [1975] task variation), this reversal from practice with a spatially incompatible mapping was found for both the congruent and the incongruent relevant stimulus-response mappings. Thus, task-defined associations between stimulus location and response location affect performance when location is changed from relevant to irrelevant, apparently through producing automatic activation of the previously associated response.

Index of norms and ratings published in the Psychonomic Society journals.

The journals of the Psychonomic Society have served as outlets for numerous stimulus norms and ratings. Such norms are useful to researchers in a variety of areas for manipulating and controlling stimulus attributes. This article presents an index of 142 norms published in the Society's journals, categorized according to the types of materials and ratings that are included in each.

Translating between orthogonally oriented stimulus and response arrays in four-choice reaction tasks.

Three experiments examined performance of four-choice reaction tasks using stimulus and response arrays oriented along parallel or orthogonal axes. All used a procedure in which pairs of locations were precued in advance of the target stimulus. Responses were slower for orthogonal than for parallel stimulus-response sets, but the pattern of relative precuing benefits was similar. Complete transfer occurred when the stimulus array was changed from an orthogonal to a parallel orientation with respect to the response array after three sessions of practice. Transfer was also evident when the orientation of the response array was changed from orthogonal to parallel with respect to the stimulus array, as long as the assignment of stimulus locations to fingers was not altered. The results suggest that coding in the four-choice task is by relative location regardless of whether the stimulus and response sets are oriented orthogonally, and that an additional transformation operation to align the frames of reference is performed for orthogonal orientations.

Scheduling processes in working memory: instructions control the order of memory search and mental arithmetic.

Humans must often use working memory to execute processes one at a time because of its limited capacity. Two experiments tested where limits in access to working memory occur. Subjects searched a short-term memory set for one stimulus digit and performed mental arithmetic with another stimulus digit. In one experiment, they were told to carry out the mental arithmetic before the memory search and to make the arithmetic response first. In the other, they were instructed to perform the tasks in the opposite order. The overt responses were executed in the prescribed order. Moreover, the covert working memory processes were executed in the prescribed order, as revealed by a critical path network analysis of reaction times. Results are explained in terms of a double-bottleneck model in which central processes and responses are constrained to be carried out for one task at a time.

Set- and Element-Level Stimulus-Response Compatibility Effects for Different Manual Response Sets.

In a previous study of two-choice reactions, pairings of spatial stimuli with bimanual presses made on a keyboard and verbal stimuli with unimanual aimed movements made on a display screen showed higher set-level compatibility than the opposite pairings; element-level compatibility (i.e., mapping) effects were also larger for the conditions with high set-level compatibility than for those whose set-level compatibility was low. In the 4 experiments described here, the relevant factors were isolated, allowing the determinants of those compatibility differences to be evaluated in more detail. Forty-eight students participated in Experiment 1, and 24 each in Experiments 2, 3, and 4. The primary determinant of the set-level compatibility variation was whether the response alternatives involved 1 or 2 effectors, but the differences in element-level compatibility effects were determined primarily by the distinction between responding on the screen as opposed to on the keyboard. Implications for models of stimulus-response compatibility are examined.

Cross-task cross talk in memory and perception.

The application of the additive factors method depends on finding factors that selectively influence processing stages. When all the processes for a task are in series, a factor directly influencing a process might change its output and thereby have indirect influence on succeeding processes. We investigate whether such indirect influence is possible between processes associated with different tasks being performed together. In two dual-task memory scanning and arithmetic experiments with digits as the stimuli for both tasks, information relevant for only one of the tasks nonetheless affected performance of the other. When the same digit was relevant for the two tasks, cross-task facilitation and interference were observed in some cases. Displaying the same digit for both tasks led to relatively fast response times, paralleling the effect of flankers in the response competition paradigm. But repetition of digits in memory slowed responses. It is suggested that the need for control processes to keep task information segregated is responsible for the pattern of effects.

Stimulus-response compatibility for vertically oriented stimuli and horizontally oriented responses: evidence for spatial coding.

It has previously been shown that, when stimuli positioned above or below a central fixation point ("up" and "down" stimuli) are assigned to left and right responses, the stimulus-response mapping up-left/down-right is more compatible than the mapping up-right/down-left for responses executed by the left hand in the left hemispace, but this relation is reversed for responses executed by the right hand in the right hemispace. In Experiment 1, each hand responded at locations in both hemispaces to dissociate the influence of hand identity from response location, and response location was found to be the determinant of relative compatibility. In Experiment 2 responses were made at the sagittal midline, and an inactive response switch was placed to the left or right to induce coding of the active switch as right or left, respectively. This manipulation of relative location had an effect similar to, although of lesser magnitude than, that produced by physically changing location of the response switch in Experiment 1. It is argued that these results are counter to predictions of a movement-preference account and consistent with the view that spatial coding underlies compatibility effects for orthogonally oriented stimulus and response sets.