Positive effect of heterogeneity of difference on thesame-different disparity in letter matching

Subjects judged whether two adjacent letters were identical or different.Different pairs were similar, for example HM, DO, VY, or dissimilar, for example DY, HV,MO. According to the noisy-operator theory, increasing the heterogeneity of difference (external noise) by intermixing similar and dissimilardifferent pairs ought to produce faster but less accurate responses ondifferent trials. As predicted, the tendency to make more false-different responses (i.e., errors on same pairs) decreased when the similar and dissimilardifferent pairs were intermixed rather than presented in separate blocks. The fast-same effect did not change, however, seemingly due to criterion misadjustment. Proctor and Rao apparently found no effect of heterogeneity of difference on RT and errors because they used a less sensitive procedure (between-subjects design; different set of letters for more and less heterogeneous conditions). Consistent with the internal-noise principle, but not with the response-competition model of Eriksen, O’Hara, and Eriksen, the enhanced fast-same effect on blocks containing only similar (vs. dissimilar)different pairs was accompanied by an increased preponderance of false-different errors.     

Effect of intermixed foveal and parafoveal presentation onsame-different judgments: Evidence for a criterion-inertia model

Subjects judged whether two adjacent letters, which were presented either 0.5° (foveal or near condition) or 2.0° (parafoveal or far condition) from fixation, were identical or different. The preponderance of false-different responses (i.e., errors onsame trials) over false-same ones increased, whereas the fast-same effect was eliminated, on the far pairs, but only when they were intermixed with near pairs rather than presented in separate (pure) blocks of trials. Intermixing the near and far pairs produced the opposite trends on near trials (i.e., smaller preponderance of false-different errors, larger fast-same effect). Carr et al., who presented trigrams, found a similar criterion misadjustment, which likewise depended on intermixed presentation. They proposed that their easy (familiar or orthographically regular) pairs produced a bias or criterion shift towards “same.” No obvious biasing features were present in the near or far pairs, however, so the criterion misadjustment found here was attributed to the combined effect of internal noise and criterion inertia, not to criterion shifting. Increasing the level of internal noise on far trials produced more spurious perceived mismatches, but on mixed blocks of near and far trials, subjects relied on a common, compromise criterion for responding versus rechecking (recheck moderate perceived differences), instead of the separate, more appropriate criteria for near trials (recheck small differences) and far trials (recheck large differences) used on pure blocks.     

Nominal and physical decision criteria insame-different judgments

We propose a model in which the physical and nominal dimensions of letter pairs are compared independently of whether subjects use physical (shape task) or nominal (name task) identity as the decision criterion. We attempt to explain the fast-same effect, the preponderance of false-different errors, and thenominal-physical disparity as results of congruent and incongruent outputs of physical and nominal comparison devices that function in both tasks. Subjects performed both tasks with and without response deadlines. The stimuli were presented foveally or unilaterally to one or the other hemisphere. With foveal presentations, thenominal-physical disparity disappeared when congruent and incongruent cells were compared, the fast-same effect occurred only in the shape task, and there was a preponderance offalse-different errors only in the name task. Response times and error patterns from centrally presented trials conformed to the predictions of the model. Performance patterns from the lateralized trials conformed only partially. The implications of the data are discussed in the context of several theoretical models ofsame/ different judgments.     

Evidence that thesame-different disparity in letter matching is not attributable to response bias

When pairs of letters or letter strings are judged assame ordifferent, correctsame responses are usually faster than correctdifferent responses. Recently, Ratcliff and Hacker (1981, 1982) have argued that thissame-different disparity is likely attributable solely to a bias to respondsame. The present article reports an experiment in which the relative bias to respondsame ordifferent was varied for matches of single-letter pairs. Bias was manipulated by having 80, 60, 40, or 20 pairs in a block of 100 besame, with the remainder beingdifferent. For both sequential and simultaneous presentation of the letters,same reaction times had an overall advantage overdifferent reaction times that could not be attributed to response bias. Moreover, consistent with Proctor’s (1981) facilitation principle, this reaction time disparity was greater with sequential presentation than with simultaneous presentation. The larger reaction time advantage forsame pairs with sequential presentation was obtained without an increase in the relative number of false-same responses, supporting the view that the facilitation is attributable to changes in sensitivity and not to changes in encoding criteria.     

On the masking and disclosure of unconscious elaborate processing. A reply to Van Opstal, Reynvoet, and Verguts (2005)

We have recently argued that unconscious numerical stimuli might activate responses by a match with prespecified action trigger codes (action trigger account) rather than by semantic prime processing (elaborate processing account). [Van Opstal, F., Reynvoet, B., and Verguts, T. (2005). How to trigger elaborate processing? A comment on Kunde, Kiesel, and Hoffmann (2003). Cognition] replicate one piece of evidence for our inference—an inefficiency of primes not presented in target format (verbal or Arabic). But this was found only with letter masks and not with hash masks. The authors conclude that letter masks block unconscious prime processing, and that elaborate processing can account for unconscious priming effects if all its (sometimes subtle) side conditions are considered. We agree that the type of mask in general is an important factor in priming studies but we note that (i) the authors' mask-blocking hypothesis is not well supported by the data, (ii) clear evidence for semantic prime processing in their study is lacking and, (iii) differences in mask efficiency (rather than mask type) might account for the conflicting results. To corroborate this inference we replicate van Opstal et al.'s results with letter masks but reduced mask efficiency. Altogether their data do not challenge the action-trigger account nor do they strongly support the elaborate processing view.     

Null effects of exposure duration and heterogeneity of difference on thesame-different disparity in letter matching

The rechecking and external-noise postulates of Krueger’s (1978) noisy-operator theory were examined in three letter-matching experiments. Rechecking was tested by varying exposure duration, both without (Experiment 1) and with (Experiment 2) a subsequent noise mask. Predictions of a decreasedsame-different reaction time disparity and an increase in falsedifferent errors at brief exposures were not borne out. The external-noise postulate was tested by varying the degree of heterogeneity of difference between letter sets. The prediction of a smallersamedifferent reaction time disparity for the more heterogeneous letter set was not obtained. Thus, the results did not support internal noise as the basis of thesame-different disparity, but were more consistent with response-inhibition accounts.     

Probing Proctor's priming principle: the effect of simultaneous and sequential presentation on same-different judgments

Three explanations (internal noise, priming, relative frequency) of the fast-same effect were examined. The internal-noise principle, which predicts more errors as well as faster correct judgments on same pairs, was consistently confirmed even with sequential presentation. More elusive was priming, that is, the facilitation of encoding from letter repetition with sequential presentation. Priming was inhibited by the presence of intertrial letter repetition. The error data indicated that priming involves an increased efficiency in encoding (d'), as Proctor claimed, rather than a criterion shift (beta), as Krueger and Shapiro claimed. An alternative to the priming explanation, based on the greater susceptibility of simultaneous presentation to analytical processing, was tested and disconfirmed. Stimulus-set size did not affect the speed advantage for same pairs, thus disconfirming the relative-frequency explanation, according to which same judgments are faster because typically there are fewer unique same than different pairs.     

Response competition effects insame-different judgments

An account ofsame-different discriminations that is based upon a continuous-flow model of visual information processing (C. W. Eriksen & Schultz, 1979) and response competition and inhibition between the responses by which the subject signifies his judgment is presented. We show that a response signifyingsame will on the average be executed faster due to less priming or incipient activation of the competing response,different. In the experiment, the subjects matched letters on the basis of physical identity. The degree of priming ofdifferent responses on same trials and ofsame responses ondifferent trials was manipulated by an extraneous noise letter placed in the display. Latency for judgments onsame trials increased as the feature overlap of noise and target letters decreased. Latencies were shorter ondifferent trials when the noise letter was dissimilar to either target letter than when the noise letter was the same as one of the targets. These results were consistent with the response-competition interpretation.     

Disruptive effects of prior information on tachistoscopic recognition

Smith, Haviland, Reder, Brownell, and Adams (1976) found tachistoscopic letter recognition to be disrupted by advance information about possible letter alternatives. An association of “before-disruption” with a bias to respond “same” in same-different judgment led Smith et al. to conclude that incidental mask features corresponding to a precued letter were erroneously incorporated into the target letter decision. Experiments 1 and 2 in the present study failed to replicate the before-disruption effect under conditions similar to those of Smith et al., although precuing produced a strong bias to respond “same.” Similarity between “same” and “different” alternatives was manipulated in Experiment 3 by selecting letter pairs differing in one critical feature (P-R, O-Q, C-G, F-E) for one group of subjects, and re-pairing the same letters (P-G, O-E, C-R, F-Q) for another group. Contrary to Smith et el., precuing interacted significantly with pair similarity, such that before-disruption occurred only with similar alternatives. In contrast, precuing produced equivalent “same-bias” in both groups. The dependence of before-disruption on pair similarity was extended to two-alternative forced-choice recognition in Experiment 4. Together with inconsistencies in the Smith et al. data and more detailed analysis of present recognition errors, the results suggest (1) the before-disruption and same-bias effects of precuing are mediated by separate mechanisms, and (2) before-disruption reflects loss of target letter information rather than direct incorporation of extraneous mask features.     

Are nominal same-different matches slower due to differences in level of processing or to response competition?

Eriksen, O’Hara, and Eriksen (1982) have proposed that the latency advantage ofsame overdifferent judgments when the match is based upon physical identity is due to differential amounts of response competition between the responses by which the judgment ofsame ordifferent is signified. Responses of “different” are slowed by a high level of priming in the competing response signifyingsame. In the present experiment, the response competition model is extended to nominal matches and in particular to what Proctor 1198D has termed the “name-physieal disparity”—a pair of letters are more rapidly judged to have the same name if they are the same ease (e.g., a a) than if they are in different eases (e.g., A a). While response competition effects were found to occur in nominal matches of this kind, the name-physieal disparity was greater than could be attributed solely to response competition. Evidence was obtained that part of the name-physieal disparity could be attributed to the subject’s having two chances to make a-nominal raatch when the letter pair was identical both physically and in name. The match could be made either on the basis of the physical or the name code. It was assumed that name and physical codes were processed at least partially independently.     

Comparison processes on visual mental images

Three experiments were conducted to test whether visual mental images and visual perceptual representations possess equivalent structural properties and undergo functionally equivalent comparison processes. In Experiment 1, subjects were required to perform asame-different letter classification in which the two letters were shown in succession. The first letter in the pair either was actually presented (perceptual condition) or had to be actively generated (imaginal condition). Both conditions showed that (1) response latencies fordifferent decisions decreased as a function of the degree of difference (segment effect), and (2) same decisions were faster than the fastestdifferent ones (fast same effect). In Experiment 2, the imaginal condition only was employed, but no imagery instructions were given and very strict time constraints were assigned. In spite of these restrictions, subjects apparently generated and used visual images, as attested by the fact that the results were comparable to those of the previous experiment. In Experiment 3, three experimental manipulations were introduced to prevent the use of visual images. Such manipulations proved effective, as shown by the disappearance of the segment effect. It was concluded that in the visual modality images and percepts are equivalent in structure and are processed in a very similar way.     

Task effects reveal cognitive flexibility responding to frequency and predictability: Evidence from eye movements in reading and proofreading

It is well-known that word frequency and predictability affect processing time. These effects change magnitude across tasks, but studies testing this use tasks with different response types (e.g., lexical decision, naming, and fixation time during reading; Schilling, Rayner, & Chumbley, 1998), preventing direct comparison. Recently, Kaakinen and Hyönä (2010) overcame this problem, comparing fixation times in reading for comprehension and proofreading, showing that the frequency effect was larger in proofreading than in reading. This result could be explained by readers exhibiting substantial cognitive flexibility, and qualitatively changing how they process words in the proofreading task in a way that magnifies effects of word frequency. Alternatively, readers may not change word processing so dramatically, and instead may perform more careful identification generally, increasing the magnitude of many word processing effects (e.g., both frequency and predictability). We tested these possibilities with two experiments: subjects read for comprehension and then proofread for spelling errors (letter transpositions) that produce nonwords (e.g., trcak for track as in Kaakinen & Hyönä) or that produce real but unintended words (e.g., trial for trail) to compare how the task changes these effects. Replicating Kaakinen and Hyönä, frequency effects increased during proofreading. However, predictability effects only increased when integration with the sentence context was necessary to detect errors (i.e., when spelling errors produced words that were inappropriate in the sentence; trial for trail). The results suggest that readers adopt sophisticated word processing strategies to accommodate task demands.     

Intertrial effects of same-different judgements

Specific intertrial effects (repetition effects) and general intertrial effects (refractoriness or persisting attention to the preceding trial) were studied with the same-different judgment task, which dissociates the effects of response repetition and stimulus repetition. Response repetition alone did not facilitate performance. Stimulus repetition did aid performance, but mainly when accompanied by response repetition. Subjects tended to avoid the normal comparison process by using the (invalid!) “bypass rule” (Fletcher and Rabbitt, 1978): repeat the response if the stimulus or some aspect thereof (letter contents, size, position) is repeated from the preceding trial, otherwise change the response. As to general effects, partial refractoriness was evident at response execution, but not at earlier processing stages. Mean RT increased, but errors decreased, as the response-stimulus interval (RSI) between trials decreased. Presenting a new letter pair immediately after the preceding response produced a delay, but subjects used the waiting time, while the response system recovered or was redirected to the present trial, to improve the accuracy of their decision.     

Forest before trees? It depends where you look

Because it may be deduced from the more elementary principles of visual processing, global precedence (Navon, 1977) is not a primary perceptual principle. Subjects were presented with a large letter made out of small ones and asked to make an identification response on the basis of either the large or small letter. When fixation was controlled to provide adequate stimulation from the small letter, there was no difference in reaction time (RT) between the large and small targets. Also, there was no difference in interference due to response incompatibility of the unattended letter based on target size. However, when the stimulus was presented peripherally, unpredictably to the right or left of fixation, RT was faster to the large target and interference was substantially greater for the small target. Functions for the development of associative strength and associative interference are presented. Global precedence is dependent on factors tending to degrade small stimuli more than large ones.     

Partial report, visual matching, and search as a function of cue-delay

Three experiments are reported where a cue that was varied in time indicated a letter pair (or pairs) in a circular display with six pairs. The S had either to report letters from a pair (Exp. 1) or to decide about the equality of the letter pair (Exp. 2) or to decide about the presence of a target letter given with various delays (Exp. 3). Exp. 1 shows a short-lived partial report superiority, the loss being primarily due to adjacency errors. In Exp. 2 a short loss in the correct same decisions, but almost no loss in the correct "differents" was observed. In spite of its search task character, Exp. 3 showed the same loss as Exp. 1, 2. In all experiments performance recovered with the latest ISI (1 sec). The results of Exp. 1 can be explained by post-categorical accounts of the partial report (PR-) effect (loss of positional information), those of Exp. 2 by visual confusion, i. e. a precategorical account, those of Exp. 3 by neither. The results suggest that the PR-effect might be due to non-visible persistence rather but to visible persistence. A theory of early visual processing which would also explain the PR-effect is still lacking.     

Forced serial processing of words and letter strings: A reexamination

Words and nonword strings, three and seven letters long, were displayed serially (i.e., one letter at a time) or simultaneously, with or without a backward mask following display of each letter or string. Recognition of words, and of individual letters within words, was markedly impaired in the masked serial condition relative to the unmasked serial, unmasked simultaneous, and masked simultaneous conditions. Analogous differences were smaller or nonexistent for seven-letter nonwords; however, three-letter nonwords produced relatively “wordlike” data. Implications for the issue of spatially serial vs. parallel processing in word recognition are discussed.     

Obsessive-compulsive tendencies are associated with a focused information processing strategy

The study examined the hypothesis that obsessive–compulsive (OC) tendencies are related to a reliance on focused and serial rather than a parallel, speed-oriented information processing style. Ten students with high OC tendencies and 10 students with low OC tendencies performed the flanker task, in which they were required to quickly classify a briefly presented target letter (S or H) that was flanked by compatible (e.g., SSSSS) or incompatible (e.g., HHSHH) noise letters. Participants received 4 blocks of 100 trials each, two with 50% compatible trials and two with 80% compatible trials and were informed of the probability of compatible trials before the beginning of each block. As predicted, high OC participants, as compared to low OC participants, had slower overall reaction time (RT) and lower tendency for parallel processing (defined as incompatible trials RT minus compatible trials RT). Low, more than high OC participants tended to adjust their focused/parallel processing including a shift towards parallel processing in blocks with 80% compatible trials and in trials following compatible trials. Implications of these results to the cognitive theory and therapy of OCD are discussed.     

Evidence for a parallel input serial analysis model of word processing

A parallel input serial analysis (PISA) model of word processing was developed and tested. The goal was to expand on the "critical processing duration" hypothesis of Johnson, Allen, and Strand (1989) so that both single-word and multiple-word presentation, letter detection data could be explained. In Experiments 1-3 four different word frequency categories on a single-presentation, letter detection task were used. These three experiments indicated that there was a curvilinear relationship between word frequency and letter detection reaction time (RT). That is, letter detection RTs for medium-high-frequency words were significantly longer than letter detection RTs for very-high-, low-, and very-low-frequency words. These results support the PISA model rather than the Healy, Oliver, and McNamara (1987) version of the unitization model. In Experiments 4-5 multiple-presentation (i.e., two words), letter detection tasks were used. The PISA model could also account for the results from these two experiments, but the unitization model could not.     

Response time distributional evidence for distinct varieties of number attraction

Speakers are known to make subject–verb agreement errors both when a number-mismatching noun intervenes between the head of the subject phrase and the verb (e.g., ¹The key to the cabinets are on the table) and in configurations in which there is a number-mismatching noun that does not intervene (e.g., ¹The cabinets that the key open are on the second floor). Using a two-choice response time (RT) paradigm, Staub (2009) found that correct agreement decisions were also slowed in both cases. The present article reports a new experiment designed to explore whether these two RT effects are qualitatively similar or different. Fitting of the ex-Gaussian distribution (Ratcliff, 1979) to individual subjects’ RT data, in each condition, demonstrated that the effect of an intervening number attractor on correct RT is due to both a shifting of the distribution to the right and to increased skewing, while the effect of a non-intervening attractor is almost entirely a skewing effect. A non-parametric vincentizing procedure supported these conclusions. These findings are taken to support the view that these two types of number attraction involve distinct processing mechanisms.     

Letter versus dot stimuli as tools for “splitting the normal brain with reaction time”

Filbey and Gazzaniga (1969) found simple dot-present or -absent reports averaged 35 ms slower for the left than for the right visual field. Other data suggests that verbal processing efficiency differences between the cerebral hemispheres, rather than transcallosal transfer time alone, must be tapped to obtain half-field differences as large as 35 ms. Three experiments were conducted. The first failed to show any half-field differences in vocal RT for dot detection; the second replicated previous reports of significant right field superiority of vocal RT to letter stimuli for right handers, and also showed a substantially smaller half-field difference for left handers; the third experiment, utilizing the fixation control procedure of the second experiment, again failed to show half-field differences for the dot detection paradigm. Differences between the Filbey and Gazzaniga and present results probably reflect important procedural differences. We conclude that transcallosal transfer time for simple dot information is much smaller than assumed by Filbey and Gazzaniga and that the letter report-time task taps hemispheric asymmetries of verbal processing efficiency.