Yang Seok Cho

Polarity Correspondence: A General Principle for Performance of Speeded Binary Classification Tasks.

Differences in performance with various stimulus-response mappings are among the most prevalent findings for binary choice reaction tasks. The authors show that perceptual or conceptual similarity is not necessary to obtain mapping effects; a type of structural similarity is sufficient. Specifically, stimulus and response alternatives are coded as positive and negative polarity along several dimensions, and polarity correspondence is sufficient to produce mapping effects. The authors make the case for this polarity correspondence principle using the literature on word-picture verification and then provide evidence that polarity correspondence is a determinant of mapping effects in orthogonal stimulus-response compatibility, numerical judgment, and implicit association tasks. The authors conclude by discussing implications of this principle for interpretation of results from binary choice tasks and future model development.

Stimulus and response representations underlying orthogonal stimulus-response compatibility effects

One of the most important findings in recent years regarding response selection is that stimulus-response compatibility (SRC) effects occur for situations in which stimulus and response sets vary along orthogonal dimensions. For two-choice tasks, two types of orthogonal SRC effects are found: an overall advantage for the up-right/down-left mapping, and mapping preferences that vary as a function of position of the response apparatus and responding hand. We review evidence regarding the nature of both types of orthogonal SRC effects. Only asymmetric coding accounts have been proposed for the up-right/down-left advantage, and the evidence indicates that this asymmetry is a property of both verbal and spatial codes. Motoric and coding accounts, as well as a hybrid account based on end-state comfort, have been proposed for the second type of orthogonal SRC effect. In this case, the effects of responseapparatus position, hand, and hand posture conform more closely to predictions of the asymmetric coding accounts than to those of the motoric accounts. We also evaluate the mechanisms proposed by the alternative accounts in terms of related literature on the properties of spatial and verbal codes. Evidence indicates that spatial information is represented in categorical and coordinate codes, and both categorical spatial codes and verbal codes are asymmetric. Experiments on mental rotation suggest that it is unlikely that the direction of rotation is determined automatically by movement constraints, as the end-state comfort hypothesis suggests. An explanation in terms of salient features and referential coding can accommodate the range of orthogonal SRC effects.

Influences of hand posture and hand position on compatibility effects for up-down stimuli mapped to left-right responses: Evidence for a hand referent hypothesis

Unimanual left-right responses to up-down stimuli show a stimulus-response compatibility (SRC) effect for which the preferred mapping varies as a function of response eccentricity.Responses made in the right hemispace and, to a lesser extent, at a midline position, are faster with the up-right/ down-left mapping than with the up-left/down-right mapping, but responses made in the left hemispace are faster with the up-left/down-right mapping.Also, for responses at the midline position, the preferred mapping switches when the hand is placed in a supine posture instead of the more usual prone posture.The response eccentricity effect can be explained in terms of correspondence of asymmetrically coded stimulus and response features, but it is not obvious whether the hand posture effect can be explained in a similar manner.The present study tested the implications of a hypothesis that the body of the hand provides a frame of reference with respect to which the response switch is coded as left or right.As was predicted by this hand referent hypothesis, Experiment 1 showed that the influence of hand posture (prone and supine) on orthogonal SRC was additive with that of response location. In Experiment 2, the location of the switch relative to the hand was varied by having subjects use either a normal grip in which the switch was held between the thumb and the index finger or a grip in which it was held between the little and the ring fingers.The magnitudes of the mapping preferences varied as a function of the grip and hand posture in a manner consistent with the hand referent hypothesis.

When Is an Odd Number Not Odd? Influence of Task Rule on the MARC Effect for Numeric Classification.

When classifying numbers as odd or even with left-right keypresses, performance is better with the mapping even-right/odd-left than with the opposite mapping. This linguistic markedness association of response codes (MARC) effect has been attributed to compatibility between the linguistic markedness of stimulus and response codes. In 2 experiments participants made keypresses to the Arabic numerals or number words 3, 4, 8, and 9 using the odd-even parity rule or a multiple-of-3 rule, which yield the same keypress response for each stimulus. For both stimulus modes, the MARC effect was obtained with the odd-even rule, but tended to reverse with the multiple-of-3 rule. The reversal was complete for the right response, but task rule had little influence on the left response. The results are consistent with the view that the MARC effect and its reversal are caused by correspondence of the stimulus code designated as positive by the task rule with the positive-polarity right response code.

Transfer of magnitude and spatial mappings to the SNARC effect for parity judgments.

Left-right keypresses to numerals are faster for pairings of small numbers to left response and large numbers to right response than for the opposite pairings. This spatial numerical association of response codes (SNARC) effect has been attributed to numbers being represented on a mental number line. We examined this issue in 3 experiments using a transfer paradigm. Participants practiced a number magnitude-judgment task or spatial stimulus-response compatibility task with parallel or orthogonal stimulus-response dimensions prior to performing a parity-judgment task. The SNARC effect was enhanced following a small-left/large-right magnitude mapping but reversed following a small-right/large-left mapping, indicating that associations between magnitude and response defined for the magnitude-judgment task were maintained for the parity-judgment task. The SNARC effect was unaffected by practice with compatible or incompatible spatial mapping for the parallel spatial task but was larger following up-right/down-left mapping than up-left/down-right mapping for the orthogonal spatial task. These results are inconsistent with the SNARC effect being due to a horizontal number line representation but consistent with a view that correspondence of stimulus and response code polarities contributes to the effect.

Influence of color word availability on the Stroop color-naming effect

Three experiments tested whether the Stroop color-naming effect is a consequence of word recognitions being automatic or of the color words capturing visual attention. In Experiment 1, a color bar was presented at fixation as the color carrier, with color and neutral words presented in locations above or below the color bar; Experiment 2 was similar, except that the color carrier could occur in one of the peripheral locations and the color word at fixation. The Stroop effect increased as display duration increased, and the Stroop dilution effect (a reduced Stroop effect when a neutral word is also present) was an approximately constant proportion of the Stroop effect at all display durations, regardless of whether the color bar or color word was at fixation. In Experiment 3, the interval between the onsets of the to-be-named color and the color word was manipulated. The Stroop effect decreased with increasing delay of the color word onset, but the absolute amount of Stroop dilution produced by the neutral word increased. This studys results imply that an attention shift from the color carrier to the color word is an important factor modulating the size of the Stroop effect.

Referential Coding Contributes to the Horizontal SMARC Effect.

The present study tested whether coding of tone pitch relative to a referent contributes to the correspondence effect between the pitch height of an auditory stimulus and the location of a lateralized response. When left-right responses are mapped to high or low pitch tones, performance is better with the high-right/low-left mapping than with the opposite mapping, a phenomenon called the horizontal SMARC effect. However, when pitch height is task irrelevant, the horizontal SMARC effect occurs only for musicians. In Experiment 1, nonmusicians performed a pitch discrimination task, and the SMARC effect was evident regardless of whether a referent tone was presented. However, in Experiment 2, for a timbre-judgment task, nonmusicians showed a SMARC effect only when a referent tone was presented, whereas musicians showed a SMARC effect that did not interact with presence/absence of the referent. Dependence of the SMARC effect for nonmusicians on a reference tone was replicated in Experiment 3, in which judgments of the color of a visual stimulus were made in the presence of a concurrent high- or low-pitched pure tone. These results suggest that referential coding of pitch height is a key determinant for the horizontal SMARC effect when pitch height is irrelevant to the task.

Influences of response position and hand posture on the orthogonal Simon effect

When lateralized responses are made to the locations of vertically arrayed stimuli, two types of mapping effect have been reported: an overall up–right/down–left advantage and mapping preferences that vary with response position. According to Cho and Proctors (2003) multiple asymmetric codes account, these orthogonal stimulus–response compatibility effects are due to the correspondence of stimulus polarity and response polarity, as determined by the positions relative to multiple frames of reference. The present study examined these two types of orthogonal compatibility for situations in which participants made left–right responses to the colours of a vertically arrayed stimulus set, and stimulus location was irrelevant. Although a significant orthogonal Simon effect was not evident when responding at a centred, neutral response position, the effect was modulated by response eccentricity (Experiment 2) and hand posture (Experiment 3). These effects are qualitatively similar to those obtained when stimulus location is task relevant. The results imply that, as Proctor and Chos (2006) polarity correspondence principle suggests, the stimulus polarity code activates the response code of corresponding polarity even when stimulus location is irrelevant to the task.

Influences of multiple spatial stimulus and response codes on orthogonal stimulus—response compatibility

When up-down stimuli are mapped to left-right responses, an up-right/down-left mapping advantage is found that is modified by response eccentricity and hand posture. These effects can be attributed to correspondence of asymmetric stimulus and response codes formed relative to multiple reference frames. We examined the influence of stimulus-set location on these orthogonal stimulus-response compatibility (SRC) effects. In Experiment 1, the stimulus set appeared in the upper or lower display positions. A spatial code for stimulus-set location was formed, producing Simon-type response eccentricity and hand posture effects, but this code had no influence on the coding of the relevant stimuli. In Experiment 2, the stimulus set appeared in the left, center, or right positions relative to the response location, which also varied, to dissociate the effects of response location, relative to the stimulus display and body midline. The former factor influenced the orthogonal SRC effect for both unimanual switch movements and bimanual keypresses, and the latter factor influenced the effect for only unimanual switch movements. Stimulus-set location causes orthogonal Simon-type effects when varied along the stimulus dimension and provides a referent for response coding when varied along the response dimension.

Representing response position relative to display location: Influence on orthogonal stimulus–response compatibility

Two types of stimulus–response compatibility (SRC) effect occur with orthogonal stimulus and response sets, an overall up–right/down–left advantage and mapping preferences that vary with response position. Researchers agree that the former type is due to asymmetric coding of the stimulus and response alternatives, but disagree as to whether the latter type requires a different explanation in terms of the properties of the motor system. This issue is examined in three experiments. The location of the stimulus set influenced orthogonal SRC when it varied along the same dimension as the responses (Experiments 1 and 2), with the pattern predicted by the hypothesis that the stimulus set provides a referent relative to which response position is coded. The effect of stimulus-set location on orthogonal SRC was independent of the stimulus onset asynchrony (SOA) for a marker that indicated stimulus-set side and the imperative stimulus. In contrast, a spatial correspondence effect for the irrelevant stimulus-set location and response was a decreasing function of SOA. Experiment 3 showed that the orthogonal SRC effect was determined by response position relative to the stimulus-set location and not the body midline. The results support the view that both types of orthogonal SRC effects are due to asymmetric coding of the stimuli and responses.