Intentional fixation of behavioural learning,or how R-O learning blocks S-R learning

Four experiments deal with the acquisition of knowledge for the control of voluntary behaviour. Subjects had to accomplish a computer-controlled learning task that required them to learn which one of four actions (R) had to be performed in order to attain a certain one of four outcomes (O) in the presence of one of four situational contexts (S). Reinforcements were assigned to actions according to two schedules: In the S-R condition each of the four actions was consistently reinforced in the presence of a certain situation, whereas in the R-O condition each of the actions was either always (Experiments 1-3) or mostly (Experiment 4) reinforced if a certain outcome was required. Furthermore, the type of feedback was varied. In Experiment 1, only positive or negative reinforcements were fed back, whereas in Experiments 2-4 the actions resulted in outcomes that had to be compared with the required outcomes in order to determine successes and failures. The results indicate a preference for learning R-O contingencies over learning S-R contingencies. Most subjects were so fixated on learning R-O relations that they remained completely blind to the consistent reinforcement of S-R mappings. The data suggest that, in line with the ideomotor principle, the acquisition of behavioural competence is based primarily on the formation of bidirectional action-outcome relations. Specifications of the underlying learning mechanisms are discussed.     

Associative relations in instrumental learning: The eighteenth Bartlett memorial lecture

Instrumental learning involves three primary events: a stimulus (S), a response (R), and an outcome (O). Evidence is reviewed indicating the presence of binary associations among those events, as well as a hierarchical structure of the form S-(R-O). Experiments examining the conditions that produce learning, the content of the learning once it has occurred, and the way learning maps into performance all suggest the presence of such a hierarchical structure.     

Differential outcomes effect in children: Demonstration and mechanisms

The present paper reports three experiments that examine the role of sample stimulus-outcome (S-O) and of comparison or choice response stimulus-outcome (R-O) relations in the differential outcomes discrimination learning of five-year-old children. In these experiments, S-O relations or R-O relations were maintained or removed across two different conditional discrimination tasks. The results indicated that only children who received training in either S-O or R-O relations showed positive transfer between the conditional discriminations. These data support a two-process (‘outcome expectancy’) account of differential outcomes phenomena in which each sub-problem in a discriminative conditional choice task has its own unique reinforcer, but they also indicate that both unique sample-outcome associations and unique choice-outcome associations are important contributing features to enhanced discriminative learning under differential outcomes procedures in humans. Comparison to a control in Experiments 2 and 3 indicated that merely having had previous experience with the stimuli or having previously discriminated the stimuli did not contribute to cross-discrimination transfer in the absence of prior explicit association between those stimuli and the specific differential outcomes.     

On recognizing proper names: the orthographic cue hypothesis

Five experiments investigated the recognition of proper names and common nouns using the lexical decision paradigm. In Experiments 1-3 the case of the initial letter of written stimuli was systematically varied. An advantage was consistently found for proper names written with the first letter in capital. Crucially, response times to proper names with the first letter in lowercase and to common nouns irrespective of the case of the first letter did not differ from each other. No difference between proper names and common nouns emerged in Experiment 4 where the stimuli were presented auditorily, and in Experiment 5 where a visual lexical decision task was performed with illegal non-words. The pattern of results shows that the proper name advantage is orthographic in nature and rules out an account in terms of semantic, morphological or other lexical variables. A model is proposed in which information about the case of the first letter is specified in the abstract multidimensional orthographic representation mediating written word recognition.     

Recollection and familiarity for words and faces: a study comparing Remember–Know judgements and the Process Dissociation Procedure

Measures of recollection and familiarity often differ depending on the paradigm utilised. Remember–Know (R–K) and Process Dissociation Procedure (PDP) methods have been commonly used but rarely compared within a single study. In the current experiments, R–K and PDP were compared by examining the effect of attention at study and time to respond at test on recollection and familiarity using the same experimental procedures for each paradigm. We also included faces in addition to words to test the generality of the findings often obtained using words. The results from the R–K paradigm revealed that recollection and familiarity were similarly affected by attention at study and time to respond at test. However, in the case of PDP, the measures of recollection and familiarity showed a different pattern of results. The effects observed for recollection were similar to those obtained with the R–K method, whereas familiarity was affected by time to respond but not by attention at study. These results are discussed in relation to the controlled-automatic processing distinction and the contribution of each paradigm to research on recognition memory.     

Stimulus generalization following extradimensional and intradimensional training in educable retarded children

Five related experiments investigating stimulus generalization following go/no-go discrimination training of educable retarded children are reported. Experiment 1 employed an Extradimensional paradigm in which generalization testing was on the hue dimension following training on an independent (orientation) dimension. Following True discrimination training only 25% of children showed a decremental stimulus generalization gradient on the hue dimension, though all children exhibited flat gradients in Pseudodiscrimination and S+ only control groups. An increase in difficulty of the orientation discrimination in Experiment 2 did not increase the number of decremental gradients. In Experiment 3, children who exhibited decremental gradients in Experiments 1 and 2 underwent further generalization testing with modified stimuli to establish a symmetrical gradient peaked at a hue S+ to be employed in Experiments 4 and 5. In these experiments an Intradimensional paradigm was employed with S+ and S? stimuli drawn from the hue dimension. Excitatory control by S+ and inhibitory control by S? were demonstrated, as were inhibitory consequences of S? such as peak and area shift.     

Categorization processes in mental comparisons

Five experiments explore categorization and category-based congruity effects in mental comparisons. The first 4 experiments concentrate on categorization of infinite-set small items. The experiments vary the additional items presented and whether those items appear once (Experiments 1-2) or repeatedly (Experiments 3-4). Additional items include other small items (Experiment 1), relatively large items (Experiments 2-4), and items involving nonsize dimensions (Experiment 4). The critical small items show a complete congruity effect only in Experiments 1 and 3. Results suggest that categorization of infinite-set items may be based on range information alone (Experiment 1) but that multiple categorizations based on multiple ranges (Experiment 2) may require attentional effort. Results implicate categorization as a central process in mental comparison, despite differences in ease of categorization across paradigm.     

Infant perceptual and conceptual categorization: the roles of static and dynamic stimulus attributes

Infants' categorization of animals and vehicles based on static vs. dynamic attributes of stimuli was investigated in five experiments (N=158) using a categorization habituation-of-looking paradigm. In Experiment 1, 6-month-olds categorized static color images of animals and vehicles, and in Experiment 2, 6-month-olds categorized dynamic point-light displays showing only motions of the same animals and vehicles. In Experiments 3, 4, and 5, 6- and 9-month-olds were tested in an habituation-transfer paradigm: half of the infants at each age were habituated to static images and tested with dynamic point-light displays, and the other half were habituated to dynamic point-light displays and tested with static images. Six-month-olds did not transfer. Only 9-month-olds who were habituated to dynamic displays showed evidence of category transfer to static images. Together the findings show that 6-month-olds categorize animals and vehicles based on static and dynamic information, and 9-month-olds can transfer dynamic category information to static images. Transfer, static vs. dynamic information, and age effects in infant categorization are discussed.     

Early locus of a linguistic variable in a fast priming task

The syllable and the morpheme are known to be important linguistic variables, but is such information involved in the early stages of word recognition? Syllable‐morpheme information was manipulated in the early stage of word naming by means of the fast priming paradigm. The letters in the prime were printed in a mixture of lower‐ and upper‐case letters. The change from lower to upper case occurred either at a syllable‐morpheme boundary, before the boundary, or after it (e.g., reTAKE, rETAKE, or retAKE) creating either an intact pair or a broken one. The target was always in lower case (e.g., retake). The results of Experiments 1 and 2 revealed that intact syllable and morpheme information facilitated word naming at a short Stimulus Onset Asynchrony (below awareness) but not at a long SOA, suggesting that the use of such information is automatic. A second set of experiments attempted to determine if syllable information alone could facilitate word processing. In Experiments 3 and 4, monomorphemic words were divided either at, before, or after the syllable boundary (e.g., rePEL, rEPEL, or repEL). The primes were all pseudomorphemic in the sense that the initial syllables could appear as a morpheme in other words (e.g., restate) but were not morphemic in the target words (e.g., repel). The second syllable was neither morphemic nor pseudomorphemic. Using the same SOAs as in Experiments 1 and 2, intact syllables were found to be facilitative at the short SOA, but not at the long SOA. Thus, the syllable plays a role in an early stage of word recognition. Whether morphemes that are not syllables are facilitative is still to be determined in this paradigm.     

Selective attention modulates implicit learning

The effect of selective attention on implicit learning was tested in four experiments using the "contextual cueing" paradigm (Chun & Jiang, 1998, 1999). Observers performed visual search through items presented in an attended colour (e.g., red) and an ignored colour (e.g., green). When the spatial configuration of items in the attended colour was invariant and was consistently paired with a target location, visual search was facilitated, showing contextual cueing (Experiments 1, 3, and 4). In contrast, repeating and pairing the configuration of the ignored items with the target location resulted in no contextual cueing (Experiments 2 and 4). We conclude that implicit learning is robust only when relevant, predictive information is selectively attended.     

Conceptual and physical object qualities contribute differently to motor affordances

Priming studies have demonstrated that an object’s intrinsic and extrinsic qualities (size, orientation) influence subsequent motor behavior thus suggesting that these object qualities ‘afford’ actions that are congruent with the prime. We present four experiments that aim to evaluate the relative effect of conceptual and physical object qualities on action priming. In Experiment 1 equally graspable known and unknown tools are presented as primes. In Experiment 2 the primes depict high versus low graspable unfamiliar tools, and in Experiments 3 and 4 we present simple graspable shapes versus high graspable unfamiliar or familiar tools respectively. In all experiments the (unrelated) task consists of a timed motor response to the direction of a centrally placed arrow that is superimposed on the prime. Whereas tool familiarity reveals no significant difference on reaction time (Exp 1), responses to high graspable unfamiliar tools (Exp 2) and simple graspable shapes (Exps 3 and 4) are significantly faster. We conclude that motor affordances are most readily determined by object qualities that depend on the object’s physical appearance provided by visual information. Conceptual information about the stimuli, such as semantic category or stored knowledge about its function and associated movements, does not appear to produce detectable effects of action priming in this paradigm.     

On the nature of interactions between the past and the present.

We conceptualize the past and the present as dimensions of experience and ask whether past processing must affect decisions about the present and whether present processing must affect decisions about the past. The paradigm is speeded classification: Ss classified a stimulus's past spatial position and tried to ignore information about present position (Experiments 1-4), or classified present position, while attempting to ignore past position (Experiments 5-6). We found that in classifying the past, Ss were unable to ignore present position, unless it was processed apart from the retrieval cue. In classifying the present, subjects could ignore past position completely. We conclude that a processing asymmetry exists, reflecting perhaps a logical asymmetry in the information required to make past or present decisions.     

Attention in humans and animals: is there a capacity limitation at the time of encoding?

Investigators have suggested that pigeons have a limited capacity input channel and that as a result performance suffers when information load is great. This information overload hypothesis is based on converging findings from experiments using the matching-to-sample paradigm. Fundamental among these findings are that (a) performance improves as sample duration increases, (b) performance is better when the sample contains one relevant feature (elements) than when it contains two (compounds), and (c) this element superiority effect can be reduced by making the relevant feature of compound samples predictable. Experiments 1 and 2 show that these effects occur for humans as well. However, Experiments 3, 4, and 5 show that in humans at least some of these effects do not result from information overload at the time of encoding. Thus, the assertion that these effects do reflect such a limitation in pigeons must be reevaluated.     

Perceiving circular heading in noncanonical flow fields

Five experiments examined circular heading perception with optical flows that departed from the canonical form. Noncanonicity was achieved through nonrigidity of the environment (Experiments 1 and 2), oscillations of the point of observation (Experiment 3), and the bending of light (Experiments 4 and 5). In Experiments 1 and 2, perception was impaired more by nonrigidity of the ground plane than by nonrigidity of the medium. In Experiment 3, perception was unimpaired by noncanonical flows induced by the bounce and sway of observer locomotion. In Experiments 4 and 5, perception was not impaired when light paths were distorted by a spherical projection, but perception was impaired when they were distorted by a sine function. Results are discussed in relation to the hypothesis that the information for perceiving heading is the ordinal pattern of optical flow.     

Adult age differences in memory in relation to availability and accessibility of knowledge-based schemas

Three experiments investigated whether, over adulthood, the use of schemas to process and remember new information increases (developmental shift hypothesis), decreases (production deficiency hypothesis) or remains constant (age-invariance hypothesis). Effects of schema access were studied by having young, middle-aged, and old music experts and nonexperts recall information that was relevant or irrelevant to music (Experiment 1) and by comparing young and old participants' memory for prose passages when they knew or did not know the subject of the passage (Experiments 2 and 3). In each case, schema access facilitated memory equally across age levels, supporting the age-invariance hypothesis and implying that the basic structures and operations of memory do not necessarily change with age. Possible limits on the independence of age and schema utilization were considered in relation to the conditions under which each of the two alternative hypotheses might hold.     

Visual search does not remain efficient when executive working memory is working

Working memory (WM) has been thought to include not only short-term memory stores but also executive processes that operate on the contents of memory. The present study examined the involvement of WM in search using a dual-task paradigm in which participants performed visual search while manipulating or simply maintaining information held in WM. Experiments 1a and 2a involved executive WM tasks that required counting backward from a target digit and sorting a string of letters alphabetically, respectively. In both experiments, the search slopes in the dual-task condition were significantly steeper than those in a search-alone condition, indicating that performing the WM manipulation tasks influenced the efficiency of visual search. In contrast, when information was simply maintained in WM (Experiments 1b and 2b), search slopes did not differ between the single- and dual-task conditions. These results suggest that WM resources related to executive functions may be required in visual search.     

Toddlers' use of metric information and landmarks to reorient

Mobile organisms can keep track of spatial location (both their own location and that of objects in the environment) using either an external referent system or one centered on the self and updated by information about movement through space. When the latter system is disabled (e.g., by rapid turning), aspects of the external world must be used to reestablish orientation. Recently, it has been claimed that, both for rats and for human toddlers, reorientation is achieved using a geometric module that accepts only information about the metric properties of the environment (C. R. Gallistel, 1990; L. Hermer & E. S. Spelke, 1994, 1996). In a series of experiments, this paper confirms that geometric information is used for reorientation by young children, but gives reason to doubt that the use of this information is achieved using a module impenetrable to nongeometric information.     

Discriminating preexperimental (semantic) from learned (episodic) associations: A speed-accuracy study

This research investigates the process by which people discriminate preexperimental (semantic) from experimental (episodic) associations. Subjects were instructed to recognize (reply old) only to experimentally studied materials. The questions are how is context information used to select relevant memories, and how successful is the exclusion of irrelevant information? The recognition accuracy and the retrieval speed (rate of approach to asymptotic accuracy) are jointly measured using a speed-accuracy trade-off (SAT) paradigm, with collateral reaction time (RT) experiments. Experiment 1 presented both semantically related and unrelated pairs for study. In Experiment 3, semantically related pairs were never presented for study and preexperimentally related lures could be rejected by rule. Semantically related lures in both of these SAT experiments showed evidence for elevated false alarm rates early in retrieval, followed by late suppression of false alarms (at about 1 s). When related pairs were studied in the experiment, suppression was incomplete; when related pairs were never studied, rule-based supersuppression obtained. Results from collateral reaction time studies (Experiments 2 and 4) showed points that corresponded to the pattern of results in Experiments 1 and 3 near asymptote, although the RT data by themselves would have been interpreted quite differently. These results are compatible with a single-store, two-phase retrieval model in which context information, or recall-like information about correct pair mates, is used to correct spurious false alarms resulting from the incomplete filtering of semantic information.     

Inertia tensor and weight-percept models of length perception by static holding

S. J. Lederman, S. R. Ganeshan, and R. E. Ellis (1996) reported an experiment demonstrating that for occluded rods of equal mass and length but different diameters length perception by static holding was larger for rods of smaller diameter. They concluded that participants inferred length from illusory weight percepts. However, rods of equal mass and length that differ in diameter also differ in the eigenvalues of their respective inertia tensors. In the present experiments, the authors manipulated the diameters (Experiment 1) and the inertial eigenvalues (Experiments 4 and 5) of statically held objects. As has been shown with wielded objects, perceived length was a function of the eigenvalues. Additional experiments failed to confirm the expectation from the weight-percept model that perceived length maps to the estimated weight (Experiments 2 and 3). Physical quantities, not psychological quantities, seem to explain length perception by static holding.     

Biased retellings of events yield biased memories

When people retell events, they take different perspectives for different audiences and purposes. In four experiments, we examined the effects of this postevent reorganization of events on memory for the original events. In each experiment, participants read a story, wrote a biased letter about one of the story characters, and later remembered the original story. Participants' letters contained more story details and more elaborations relevant to the purpose of their retellings. More importantly, the letter perspective affected the amount of information recalled (Experiments 1, 3, and 4) and the direction of the errors in recall (Experiments 1 and 3) and recognition (Experiment 2). Selective rehearsal plays an important role in these bias effects: retelling involves selectively retrieving and using story information, with consequent differences in memory. However, biased memory occurred even when the biased letters contained little, if any, specific information (Experiment 4) or contained the same amount and kinds of story information as a neutral control condition (Experiment 3). Biased memory is a consequence of the reorganizing schema guiding the retelling perspective, in addition to the effects of rehearsing specific information in retelling.