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.     

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.     

Same—differentjudgments of multiletter strings: Insensitivity to positional bias and spacing

Several recent studies of multiletter matching have included pairs of strings that have-the-same letters in different positions (rearranged pairs). The task can be defined such that these rearranged pairs are correctly classified asdifferent (i.e., subjects respond “same” only if the strings have the same letters in the same positions—the order task) or assame (i.e., subjects respond “same” if the strings have the same letters regardless of their positions—the item task). The order task produces left-to-right serial-position effects, whereas the item task produces U-shaped serial position effects. Because these differences suggest that subjects may be able to exert strategic control over the comparison process, two sets of experiments were designed to test whether or not subjects can change the relative weightings devoted to the respective serial positions. In Experiments 1 and 2, the probability that a mismatch occurred in the different positions was manipulated. In Experiments 3 and 4, the physical spacing between letters, as well as whether or not the spaces were filled with neutral noise characters, was varied. None of the manipulations had much influence on the serial-position effects. Thus, the distinct serial-position effects for the order and item tasks apparently are mandatory and not due-to-any voluntary-comparison strategy.     

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.     

Causes of young children's confusion of same and different

Three experiments are reported that explore 3-year-olds' and adults' understanding of the words, same and different. In the first, 3-year-olds selected a bead that was “the same color as” or “a different color from” a target bead. In the second, 3-year-olds selected a bead that was “the same in some way as” or “different in some way from” a target bead. Contrary to results reported previously, the majority of consistent responders chose a bead identical with the target in response to the different instruction in both experiments. The rates of both incorrect different responding and incorrect same responding were greater in Experiment II than in Experiment I. In Experiment III, adults chose objects that were “the same as” or “different from” a target; unlike the children, they never chose a target-identical object in response to different instructions. It is argued that children and adults treat same and different differently, and that children's task performance is influenced by three factors: semantic, pragmatic, and nonlinguistic.     

Masked priming effect reflects evidence accumulated by the prime

In the same–different match task, masked priming is observed with the same responses but not different responses. Norris and Kinoshita's (2008) Bayesian reader account of masked priming explains this pattern based on the same principle as that explaining the absence of priming for nonwords in the lexical decision task. The pattern of priming follows from the way the model makes optimal decisions in the two tasks; priming does not depend on first activating the prime and then the target. An alternative explanation is in terms of a bias towards responding “same” that exactly counters the facilitatory effect of lexical access. The present study tested these two views by varying both the degree to which the prime predicts the response and the visibility of the prime. Unmasked primes produced effects expected from the view that priming is influenced by the degree to which the prime predicts the response. In contrast, with masked primes, the size of priming for the same response was completely unaffected by predictability. These results rule out response bias as an explanation of the absence of masked priming for different responses and, in turn, indicate that masked priming is not a consequence of automatic lexical access of the prime.     

Prior probabilities and representational momentum

In many previous experiments on representational momentum (in which memory for the final location of a moving target is displaced in the direction of target motion), participants judged whether a probe presented after a target vanished was at the same location where that target vanished or at a different location. The experiments reported here manipulated the actual or expected prior probability a same response to such a probe would be correct. In Experiment 1, a same response was correct on 10%, 30%, 50%, 70%, or 90% of the trials, but observers were not instructed regarding these probabilities. In Experiment 2, a same response was correct on 11% of the trials, but different groups of participants were instructed that a same response would be correct on 10%, 30%, 50%, 70%, or 90% of the trials. Probabilities of a same response to different probe positions, weighted mean estimates of representational momentum, hit rates and false alarm rates, and d′ and ß are reported. Representational momentum occurred in all conditions but was not influenced by actual or expected prior probability a same response would be correct. The data suggest representational momentum does not result from changes in sensitivity, and a distinction between performance bias and competence bias is introduced.     

Evidence for a conceptual account of same-different discrimination learning in the pigeon

We trained pigeons to peck two different buttons in response to 16-iconsame arrays versus 16-icondifferent arrays. In thesame arrays, the icons were all the same as one another, whereas in thedifferent arrays, the icons were all different from one another. In Experiment 1, we upset the spatial regularities of the displays by disarranging the icons—randomly displacing each icon to reduce the degree of perceptual order. The pigeons’ discriminative performance was unaffected by disarranging. In Experiment 2, spatial regularities were disturbed by varying the rotation of the icons within a display. Again, no disruption in discriminative performance was observed. These and other findings suggest that pigeons treat the 16 icons as either the same or different despite changes in the spatial organization or orientation of the icons, thus implicating a conceptual rather than a perceptual process in same—different discrimination.     

Position effects in chunked linear orders

Summary When someone is asked which of two items from a linearly ordered set of items comes first in that order, reaction time decreases with increasing distance between the two items in the given order. This is known as thedistance effect, a very robust finding in studies on linear orders. Surprisingly, investigations onchunked linear orders show unexpected diverse results. For example, reaction times todifferent probes (i. e., probes with items from different chunks) are sometimes longer than those tosame probes (i. e., probes with items from the same chunk). But if subjects' latency depends on the discriminability of chunk labels vs. exact position information within a chunk,different probes should always yield faster order judgments thansame probes. Two experiments investigated whether position effects, including both end-of-list and end-ofchunk effects, can account for the unexpected finding that between-chunk probes are sometimes answered more slowly than within-chunk probes. Moreover, the linea-rorder paradigm was extended to complex action sequences with more than two chunks, using original cooking recipes as materials. The results showed thatchunk-position effects play a crucial role in comparative judgments. Probes from the first and the last chunk were answered faster than those from a middle chunk.Border items (i. e., items next to a chunk boundary) did not produce a significant effect. However, chunking affected subjects' reaction time, as was indicated by the absence of a distance effect fordifferent probes. Besides, action sequences that are ordered in time, as well as concept lists used previously, can be considered linear orders, thus supporting the view that linear orders reflect a basic representation schema of human memory.     

Effects of number of items on the baboon's discrimination of same from different visual displays

Three experiments explored the baboon's discrimination of visual displays that comprised 2 to 24 black-and-white computer icons; the displayed icons were either the same as (same) or different from one another (different). The baboons' discrimination of same from different displays was a positive function of the number of icons. When the number of icons was decreased to 2 or 4, the baboons responded indiscriminately to the same and different displays, exhibiting strong position preferences. These results are both similar to and different from those of pigeons that were trained and tested under comparable conditions. Accepted after revision: 23 May 2001 Electronic Publication     

Discrimination learning decreases perceived similarity according to an objective measure

Initial identification discriminations between two sizes and between two slants produced better overall performances on subsequent size and slant same-different discriminations, respectively. This size- and slant-specific transfer was due to an improvement on only the different pairs. Time-duration identification discriminations with the identical stimuli and response assignments improved neither overall same-different performances nor performances on different pairs. A good performance on different pairs relative to same pairs should indicate a low perceived similarity. The literature indicates that A-X and B-Y pairings produce a positive transfer on an A-versus-B discrimination when X and Y are relatively low in similarity, and also indicates that a low perceived (not physical) similarity improves discrimination learning. An increase in salience should have also improved performance on the same pairs. The conclusion: the initial discriminations decreased the perceived similarity of parts (size or slant). This decrease resembles perceptual contrast. A discrimination between two parts also seems to increase the extent to which each part is apprehended as a separate group. Therefore, the conclusion accords with the position that two groups are associated with contrast, including for visibility.     

Differential outcomes facilitate same/different concept learning

Commonly recognized, the training procedure one employs often affects the results they obtain. Here, we demonstrate for the first time that abstract-concept learning is affected by employing a differential-outcomes procedure. The differential-outcome effect has been shown to occur for item-specific strategies but has not been established for relational strategies. To test whether different-outcome expectancies can facilitate a relational strategy, eight pigeons were trained and tested in a two-item same/different task with pictures. After pecking an upper picture, they pecked a lower picture if the pictures were the same or a white rectangle if the pictures were different. Two groups of pigeons were rewarded with either different outcomes (sounds and food amounts) or same outcomes. Both groups were trained to criterion with successively larger picture sets (8–1,024 items) and were transfer tested with novel pictures following each acquisition. With the smallest training sets, neither group showed any novel-stimulus transfer. But after acquiring the task with 32 pictures, the different-outcomes group responded more accurately to novel pictures than the same-outcome group. As the training set-size increased, both groups’ transfer performance converged and became equivalent to training performance. These results show for the first time that training with different outcomes facilitates abstract-concept learning.     

Familiarity supports associative recognition memory for face stimuli that can be unitised: Evidence from receiver operating characteristics

According to dual-process models, associative recognition memory mainly relies on recollection without benefiting from familiarity. This study investigates the circumstances under which familiarity may support associative recognition judgements by comparing recognition memory for arbitrarily paired items (i.e., pairs of face stimuli depicting two different persons; interitem associations) with recognition memory for pairs of items that are highly overlapping and can be unitised into a coherent whole (i.e., pairs of physically different but very similar face stimuli depicting the same person; intraitem associations). Estimates of familiarity and recollection were derived from receiver operating characteristics. Consistent with the hypothesis that familiarity is able to support associative recognition memory, but only when the to-be-associated stimuli can be unitised, results from two experiments revealed higher familiarity estimates for intra- compared to interitem associations. By contrast, recollection for recombined pairs was higher for inter- compared to intraitem associations. We propose a hypothetical model on how intraitem associations may benefit from familiarity.     

Abstract-concept learning in Black-billed magpies (<Emphasis Type="Italic">Pica hudsonia</Emphasis>)

Abstract relational concepts depend upon relationships between stimuli (e.g., same vs. different) and transcend features of the training stimuli. Recent evidence shows that learning abstract concepts is shared across a variety species including birds. Our recent work with a highly-skilled food-storing bird, Clark’s nutcracker, revealed superior same/different abstract-concept learning compared to rhesus monkeys, capuchin monkeys, and pigeons. Here we test a more social, but less reliant on food-storing, corvid species, the Black-billed magpie (Pica hudsonia). We used the same procedures and training exemplars (eight pairs of the same rule, and 56 pairs of the different rule) as were used to test the other species. Magpies (n = 10) showed a level of abstract-concept learning that was equivalent to nutcrackers and greater than the primates and pigeons tested with these same exemplars. These findings suggest that superior initial abstract-concept learning abilities may be shared across corvids generally, rather than confined to those strongly reliant on spatial memory.     

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.     

Learning and transfer of relational matching-to-sample by pigeons

We trained pigeons on a relational matching-to-sample task to see whether a nonprimate species can discriminate higher-order “relations between relations.” We required the birds to relationally match arrays of 16 items that were chosen from five nonoverlapping sets of 20 colored computer icons. On each trial, randomly selected icons from one set were placed into a 4×4 grid to form a sample; onsame trials, all 16 icons were identical to each other, whereas ondifferent trials, all 16 icons were different from each other. After 10-20 pecks, 16-itemsame anddifferent testing arrays were presented that were created from an entirely different icon set. Because no icons were common to the sample and testing arrays, discriminating higher-order relations was required for success on the tests. As have primates in similar tasks, pigeons successfully learned and transferred this relational discrimination, suggesting that both birds and mammals possess the cognitive antecedents of analogical reasoning.     

Unitary classification in a comparison task

Sequential effects were used to diagnose whether elements in a two-object-comparison-task are represented as a perceptual unit or separately. The presence of sequential effects and absence of influences of individual elements on the subsequent trial in a successive comparison task favor the hypothesis that the elements in a pair are represented as a unit, and that a response is made to the perceptual unit. The patterns of responsetimes onsame anddifferent trials differed in-several ways; these suggested that the quality of the representations ofsame anddifferent trials may differ.     

Dissociating the generation stage in implicit and explicit memory tests: Incidental production can differ from strategic access

An assumption of the generate/recognize model of direct and indirect memory is that the generation stage is identical on explicit and implicit tests. Two experiments were conducted to examine the generation stage by requiring subjects to write down every word-stem solution they could generate on either an implicit test, a cued-recall test, or a generate/recognize test. In Experiment 1, the subjects studied words and anagrams; target generation was not significantly different on the three tests. However, in Experiment 2, the subjects studied the target words with a context word, and saw either thesame ordifferent context with the test stem. Now the generation stages dissociated, such that the context manipulation had no significant effect on the implicit test, but on the cued-recall test, more targets were generated with the same context words than were generated with different context words. The results argue against the claim that dissociations between implicit and explicit tests are due only to the addition of recognition processes on the explicit test, because the generation processes themselves can be dissociated.     

Discrimination and matching within and between hues measured by reaction times: some implications for categorical perception and levels of information processing

Summary Same-different reaction times (RTs) were obtained for pairs of color samples ranging perceptually from blue to green. In Experiment 1, observers responded with same if both stimuli in a pair were from the same hue category (i.e., blue-blue or green-green) or different if the two stimuli were from different hue categories (i.e., blue-green or green-blue). RT for same responses was faster for pairs of physically identical stimuli (A-A) than for pairs of physically different stimuli (A-a) belonging to the same hue. RT for different responses was faster for larger physical differences across a boundary between hues (A-B 6 step) than for smaller physical differences (A-B 2 step). Experiment 2 replicated and extended these findings: In one phase observers matched pairs of stimuli as same or different by categorical similarity as in Experiment 1, and in a second phase observers matched the same stimulus pairs, this time by physical similarity. Matching by categorical similarity replicated the pattern of results found in Experiment 1. Matching by physical similarity showed that RTs for different responses were equivalently fast independent of the physical difference between A-B pairs, but were faster for A-B than for A-a comparisons. Further, matching identity was faster under categorical match instructions than under physical match instructions. Results of the two experiments support a model of parallel processing of physical and categorical stimulus information in color perception. Further, these reaction-time data and their implications in color perception (for hues) parallel reaction-time data and their implications in speech perception (for phonemes).     

Visual pattern matching: Effects of size ratio, complexity, and similarity in simultaneous and successive matching

An experiment on mental transformation of size, in pairwise comparison of simultaneously or successively presented figures with respect to shape, is reported. Regardless of type of presentation (simultaneous vs. successive), figural complexity, and similarity within pairs of different-shaped figures, median latencies of both same and different responses were approximately linearly increasing functions of the linear size ratio between the patterns to be compared. The slopes of the functions showed significant effects of figural complexity and similarity for simultaneous but not for successive matching. The results suggest that successive matching was done by encoding a subpattern of the first stimulus in a pair as a mental image, transforming the image to the size format of the other stimulus, and then testing for a match; in simultaneous matching the process of encoding, transformation, and comparison appeared to be executed several times for each pair of figures. The interpretation was illustrated by a random walk model, which provided a good fit to the results. Received: 31 March 1998 / Accepted: 22 August 1998