Generalization decrement in human contingency learning

An association between a cue and an outcome will generalize to a similar novel cue to some extent, but not completely. Learning theorists refer to the discrepancy between responding elicited by the original cue and the novel cue as a generalization decrement. Two experiments used a contingency learning task with human participants to compare the size of a generalization decrement between configurations of cues that were altered by adding or subtracting compositional elements. The results suggest that adding elements to a configuration can produce a generalization decrement, but removing elements produces a more robust generalization decrement. Furthermore, the generalization decrement caused by adding elements was not likely to be caused by competing orienting responses. The results are used to contrast Pearce's (1987, 1994) and Wagner's (2003) models of stimulus generalization.     

Asymmetry of generalization decrement in causal learning

Two experiments required volunteers to learn which of various “planes” caused high levels of pollution. Novel test items were then rated as causes of pollution. Items created by adding novel features were rated at the same level as that of the original training items but items created by removing features received reduced ratings. This asymmetry of generalization decrement was not predicted by a well-known configural model of stimulus representation (Pearce, 1987, 1994) but was predicted by a recently proposed model of stimulus representation, the replaced-elements model (Brandon, Vogel, & Wagner, 2000).     

The effects of transient attention on spatial resolution and the size of the attentional cue

It has been shown that transient attention enhances spatial resolution, but is the effect of transient attention on spatial resolution modulated by the size of the attentional cue? Would a gradual increase in the size of the cue lead to a gradual decrement in spatial resolution? To test these hypotheses, we used a texture segmentation task in which performance depends on spatial resolution, and systematically manipulated the size of the attentional cue: A bar of different lengths (Experiment 1) or a frame of different sizes (Experiments 2-3) indicated the target region in a texture segmentation display. Observers indicated whether a target patch region (oriented line elements in a background of an orthogonal orientation), appearing at a range of eccentricities, was present in the first or the second interval. We replicated the attentional enhancement of spatial resolution found with small cues; attention improved performance at peripheral locations but impaired performance at central locations. However, there was no evidence of gradual resolution decrement with large cues. Transient attention enhanced spatial resolution at the attended location when it was attracted to that location by a small cue but did not affect resolution when it was attracted by a large cue. These results indicate that transient attention cannot adapt its operation on spatial resolution on the basis of the size of the attentional cue.     

Trait Anxiety and Fear Responses to Safety Cues: Stimulus Generalization or Sensitization?

Abnormal fear responding to threat cues may contribute to the aetiology and maintenance of persistent fears and pathological anxiety. Chronic anxiety may also involve abnormal fear responding to ??safety?? cues, which do not signal danger. Yet investigations of fear responding to acquired safety cues are scarce and the basis of such responding remains unclear. Moreover, previous studies do not distinguish between stimulus generalization (an associative mechanism based on perceptual similarity between threat and safety cues) and sensitization (a non-associative mechanism whereby fear responses to any novel, intense, or fear-related stimulus are temporarily elevated). This study investigated responses to acquired safety cues in volunteers with varying trait anxiety, using a novel fear conditioning paradigm designed to distinguish between effects of trait anxiety on generalization and sensitization. The paradigm used three conditioned stimuli: a threat cue (CS+) and two safety cues (CS?), one perceptually similar to the CS+ and one perceptually dissimilar. Conditioned fear to these cues was indexed by fear potentiation of the startle blink reflex, skin conductance responses, and self-report. To examine how trait anxiety moderated responses to safety cues, participants were divided into high and low trait anxiety subgroups. Startle, skin conductance, and self-reported fear measures indicated that generalization of fear occurred for the safety cue which resembled the threat cue, but not for the perceptually dissimilar safety cue, consistent with the stimulus generalization hypothesis. There was some evidence that stimulus generalization was exaggerated in anxious individuals. The current study sheds light on the mechanism by which fear responses to safety cues arise in healthy individuals, and offers some insight into the influence of this mechanism in chronic anxiety.     

Differential effects of adding and removing components of a context on the generalization of conditional freezing

Rats were conditioned across 2 consecutive days where a single unsignaled footshock was presented in the presence of specific contextual cues. Rats were tested with contexts that had additional stimulus components either added or subtracted. Using freezing as a measure of conditioning, removal but not addition of a cue from the training context produced significant generalization decrement. The results are discussed in relation to the R. A. Rescorla and A. R. Wagner (1972), J. M. Pearce (1994), and A. R. Wagner and S. E. Brandon (2001) accounts of generalization. Although the present data are most consistent with elemental models such as Rescorla and Wagner, a slight modification of the Wagner-Brandon replaced-elements model that can account for differences in the pattern of generalization obtained with contexts and discrete conditional stimuli is proposed.     

Backward blocking: The role of within-compound associations and interference between cues trained apart

Most theoretical accounts of backward blocking place heavy stress on the necessity of the target cue having been trained in compound with the competing cue to produce a decrement in responding. Yet, other evidence suggests that a similar reduction in responding to the target cue can be observed when the outcome is later paired with a novel cue never trained in compound with the target cue (interference between cues trained apart). The present experiment shows that pairing another nonassociated cue with the same outcome may be sufficient to produce a decremental effect on the target cue, but the presence of a within-compound association between the target and the competing cue adds to this effect. Thus, both interference between cues trained apart and within-compound associations independently contribute to backward blocking.     

Backward blocking: the role of within-compound associations and interference between cues trained apart

Most theoretical accounts of backward blocking place heavy stress on the necessity of the target cue having been trained in compound with the competing cue to produce a decrement in responding. Yet, other evidence suggests that a similar reduction in responding to the target cue can be observed when the outcome is later paired with a novel cue never trained in compound with the target cue (interference between cues trained apart). The present experiment shows that pairing another nonassociated cue with the same outcome may be sufficient to produce a decremental effect on the target cue, but the presence of a within-compound association between the target and the competing cue adds to this effect. Thus, both interference between cues trained apart and within-compound associations independently contribute to backward blocking.     

The role of eye‐gaze in understanding other minds

From an early age, infants are sensitive to eye‐gaze direction. This study examined Baron‐Cohen's (1994, 1995) claim that the ability to use eye‐gaze plays a crucial role in the child's developing understanding of other minds. Children aged 3 and 4 years participated in a face‐reading task, which assessed their capacity to infer mental states from a character's direction of eye‐gaze, and in a false‐belief task. As predicted, no child passed the false‐belief task without prior success on the face‐reading task. However, contrary to a central claim within Baron‐Cohen's model of mind‐reading, presentation of an eye‐gaze cue in the false‐belief task did not enhance children's performance. Furthermore, children did not solely rely on eye‐gaze as a cue, but used another directional cue (an arrow) in inferring a character's desire and intention. These results question the special role of eye‐gaze in the child's developing ability to mind‐read.     

Selective hippocampal lesions disrupt a novel cue effect but fail to eliminate blocking in rabbit eyeblink conditioning

The classical conditioning task of blocking involves the adding of a novel but redundant stimulus to a previously trained stimulus. Both blocking and novelty detection are thought to involve the hippocampus. Previously, Solomon (1977) found that nonselective aspiration lesions of the hippocampal region eliminated blocking in rabbit eyeblink conditioning. We tested the effects of selective ibotenic acid lesions of the hippocampus on blocking, as well as on novelty detection, when training is switched from a tone conditioned stimulus (CS) to a compound tone-light CS in eyeblink conditioning. Selective hippocampal lesions did not eliminate blocking but did lead to a facilitation of conditioned response (CR) acquisition to the tone and to the light, but not to the tone-light compound. Selective hippocampal lesions disrupted a CR decrement observed in sham surgical controls when transferred from tone training to tone-light training. It appears that although selective hippocampal lesions do not eliminate blocking in eyeblink conditioning, they do disrupt novelty detection and may facilitate learning to a previously blocked cue.     

Two-Year-Olds' Appreciation of the Shared Nature of Novel Object Labels

Two-year-olds' appreciation of the shared nature of object labels versus object preferences was examined in 2 studies. A total of 128 24- to 27-month-olds played a finding game with an experimenter during which they were taught a piece of information about a target object in a nonostensive learning context. In Experiment 1, children were presented with a cue signaling the referent of a novel label. In Experiment 2, children were presented with a cue signaling the experimenter's preference for a particular object. Results indicate children appreciate that knowledge of an object's label is shared between 2 different individuals, but object preferences are not.     

Infants' Understanding of Looking,Pointing, and Reaching as Cues to Goal-Directed Action

Phillips, Wellman, and Spelke (2002) provided experimental evidence indicating that by the age of 12 months infants use information about an adult's gaze-direction and emotional expression to predict action. We investigate the generality of this ability, using Phillips et al.'s paradigm across different referential gestures. If infants have a rich concept of people as intentional agents, they should encode the person-goal relation and predict action from a variety of referential gestures (such as looking and pointing), as well as from (goal-directed) reaching and grasping actions. Results of Studies 1 and 2 (within-subjects design) and Study 3 (between-subjects design) converge in indicating that Phillips et al.'s basic finding generalizes to reach-and-gaze as cue condition. In Study 3b generalization was demonstrated for point-and-gaze as cue condition. Whereas these findings suggest a general understanding of referential intent at 12 months, a control experiment (Study 4) showed that infants' action expectations could be reversed following a psychologically inconsistent habituation phase (actor points at Object A and subsequently picks up Object B) in the point-and-gaze condition, although no such reversal was obtained in the reach-and-gaze condition. These findings indicate that 1-year-old infants have well-established expectations about action goals signaled by an actor's gaze-direction and reaching and grasping movements but that an understanding of pointing as a cue to action intentions may develop later and follow a different route of acquisition.     

Landmark use by Clark’s nutcrackers (Nucifraga columbiana): influence of disorientation and cue rotation on distance and direction estimates

Many species have been shown to encode multiple sources of information to orient. To examine what kinds of information animals use to locate a goal we manipulated cue rotation, cue availability, and inertial orientation when the food-storing Clark’s nutcracker (Nucifraga columbiana) was searching for a hidden goal in a circular arena. Three groups of birds were used, each with a different goal–landmark distance. As the distance between the goal and the landmark increased, nutcrackers were less accurate in finding the correct direction to the goal than they were at estimating the distance (Experiment 1). To further examine what cues the birds were using to calculate direction, the featural cues within the environment were rotated by 90° and the birds were either oriented when searching (Experiments 2 and 3) or disoriented (Experiment 3). In Experiment 4, all distinctive visual cues were removed (both internal and external to the environment), a novel point of entry was used and the birds were either oriented or disoriented. We found that disorienting the nutcrackers so that they could not use inertial cues did not influence the birds’ total search error. The birds relied heavily but not completely on cues within the environment, as rotating available cues caused them to systematically shift their search behavior. In addition, the birds also relied to some extent on Earth-based cues. These results show the flexible nature of cue use by the Clark’s nutcracker. Our study shows how multiple sources of spatial information may be important for extracting multiple bearings for navigation.     

Attentional shift by eye gaze requires joint attention: Eye gaze cues are unique to shift attention1

Researchers have demonstrated that attentional shift triggered by gaze direction is reflexive. However, here we show that attentional shift by gaze direction was not always reflexive, but could be modulated by another's perspective. In Experiment 1, a schematic face's line of sight to a peripheral target was obstructed by a vertical barrier located between the face and the target under two conditions. However, the line of sight of the face was clear under another two conditions, in which the barrier was located behind the line of sight by utilizing a depth cue. The gaze cue shifted attention only when the line of sight was not blocked (i.e. joint attention was attained). The arrow cue did not shift attention regardless of the obstruction conditions in Experiment 2. These results suggest that attentional shift by gaze cues, but not arrow cues, involve a higher social cognitive process such as interpretation of the gaze.     

The importance of internal facial features in learning new faces

For familiar faces, the internal features (eyes, nose, and mouth) are known to be differentially salient for recognition compared to external features such as hairstyle. Two experiments are reported that investigate how this internal feature advantage accrues as a face becomes familiar. In Experiment 1, we tested the contribution of internal and external features to the ability to generalize from a single studied photograph to different views of the same face. A recognition advantage for the internal features over the external features was found after a change of viewpoint, whereas there was no internal feature advantage when the same image was used at study and test. In Experiment 2, we removed the most salient external feature (hairstyle) from studied photographs and looked at how this affected generalization to a novel viewpoint. Removing the hair from images of the face assisted generalization to novel viewpoints, and this was especially the case when photographs showing more than one viewpoint were studied. The results suggest that the internal features play an important role in the generalization between different images of an individual's face by enabling the viewer to detect the common identity-diagnostic elements across non-identical instances of the face.     

Jules Verne's Journey to the Centre of the Earth: The Secret of Counterdepressive Narratives1

The author interprets Jules Verne's Journey to the centre of the Earth with the help of Matte Blanco's theoretical framework, which describes the principle of symmetry and the principle of generalization. The fi rst states that, from the moment an element or a proposition becomes conscious, it coexists in the unconscious with its symmetrically opposite form. The second refers to the confusion of elements once they have been apprehended by thought as containing a common point; they are put into larger and larger groups which merge into an indivisible whole. Verne's novel is built on paired elements which become symmetrized (e.g. distinct minerals vs molten lava; scientifi c rationality vs madness; the living vs the dead, etc.). These elements in turn become confused with one another, thanks largely to the novel's atmosphere of oral incorporation. This allows the fusion between subject and object, and, in particular, between the orphaned hero and his dead (Earth) mother. The novel's narrative evolution through three stages (separation, fusion and de‐fusion, which are paralleled by rational, irrational and rational thought) can thus be understood as a mourning process. Similar processes can be found in other literary works.     

The Valley task: Understanding intention from goal‐directed motion in typical development and autism

A novel paradigm investigates the ability to understand an agent's intended goal in children with autism (N = 25), typically developing children (N = 46), and adults (N = 16+12) by watching a non‐human agent's kinematic properties alone. Computer animations depict a circle at the bottom of a U‐shaped valley rolling up and down its slopes and getting closer to a target resting at the top of either side of the valley. The circle's persistent motion and improving attempts evoke the attribution of the intention to reach the target, regardless of whether the circle fails or attains its goal. Children with autism are as able as controls to infer an agent's intended‐goal, disregarding its failure to reach the target. In addition, the study showed that the perception of persistent motion is a sufficient but not a necessary cue for very young children and children with autisn to attribute intention to an agent, whereas adults consider the persistent motion cue as a sufficient and necessary cue to attribute intention to an agent.     

Adding Types,But Not Tokens,Affects Property Induction

The extent to which we generalize a novel property from a sample of familiar instances to novel instances depends on the sample composition. Previous property induction experiments have only used samples consisting of novel types (unique entities). Because real-world evidence samples often contain redundant tokens (repetitions of the same entity), we studied the effects on property induction of adding types and tokens to an observed sample. In Experiments 1–3, we presented participants with a sample of birds or flowers known to have a novel property and probed whether this property generalized to novel items varying in similarity to the initial sample. Increasing the number of novel types (e.g., new birds with the target property) in a sample produced tightening, promoting property generalization to highly similar stimuli but decreasing generalization to less similar stimuli. On the other hand, increasing the number of tokens (e.g., repeated presentations of the same bird with the target property) had little effect on generalization. Experiment 4 showed that repeated tokens are encoded and can benefit recognition, but appear to be given little weight when inferring property generalization. We modified an existing Bayesian model of induction (Navarro, Dry, & Lee, 2012) to account for both the information added by new types and the discounting of information conveyed by tokens.     

Cues-pause-point language training: Structuring trainer statements to provide students with correct answers to questions

This study assessed the applicability of Cues-Pause-Point language training procedures in teaching students to obtain information from the statements of others. Two mentally retarded subjects, one of whom was echolalic, received training on one set of stimuli but not on another. During training the subjects were encouraged to remain quiet before, during, and briefly after the presentation of statements and then verbalize (i.e., answer a question) using the verbal cue(s) that had been presented in the statement. Correct responding reached 100% to the trained stimuli and both subjects' responding improved to the untrained stimuli. Posttests revealed that subjects used the trainer's statements to answer novel questions. The results suggest that Cues-Pause-Point procedures may be useful in teaching severely retarded individuals the functional use of observing and listening to others' verbal behavior.     

Context-dependent latent inhibition in taste aversion learning

The effects of taste stimulus preexposure, either in the presence or in the absence of a specific contextual cue consisting of a specific noise-producing bottle, upon the conditioning and testing of conditioned taste aversions to the taste (saccharin) plus context (noisy-bottle) compound stimulus were investigated. Four groups of rats were given preexposure trials (latent inhibition) to either: (1) novel saccharin in novel noisy bottles, (2) novel saccharin in familiar silent bottles, (3) familiar water in novel noisy bottles, (4) familiar water in familiar silent bottles, in six trials. During conditioning, saccharin was presented in the noisy bottles followed by lithium chloride for all the groups. At testing, saccharin was presented in the noisy bottles for both one-bottle and two-bottle tests of aversion. It was indicated that the conditioning decrement produced after both saccharin and noisy bottle preexposure was overwhelmingly greater than any produced after preexposure to the elements. These results, discussed in relation to current theories of latent inhibition and perceptual learning, further underline the overwhelming significance of exteroceptive contextual elements in conditioned taste aversions.     

Subjective estimates of shock probability following classical aversive conditioning with visual and gustatory conditioned stimuli

In two recent studies (Evans and Busch, 1974; Busch and Evans, in press) designed to explore the relevance of “cue appropriateness” concepts to aversion therapy, it was found that taste was a less effective CS than color. The major limitations of these studies were that conditioning was inferred from subjective ratings (although cross-validated by an unobtrusive but equally inferential performance measure), and the taste stimuli were rated more negatively in the pre-test than the color stimuli, thus creating possible ceiling effects.Quite apart from limitations in these particular studies, almost all cue appropriateness research contains methodological flaws; obvious ones are the failure to equate stimuli in different sense modalities for subjective intensity, or salience, and the failure to equate the ISIs when visual and gustatory elements of ingestible substances are the cues of interest. One of our studies (Busch and Evans, in press) partially resolved the timing problem, but in studies of visually-oriented college students the salience problem remains acute. It therefore seemed worthwhile to investigate whether, in the paradigm used in our laboratory, subjects simply attend less to taste cues than to color cues.In order to determine cue salience, a measure other than the development of CRs must be used. If an organism comes to give a CR to a certain stimulus, that is prima facie evidence of attention to, or if one prefers it, reception of, that stimulus, although generalization studies show the elements of the stimulus actually controlling the CR may not necessarily be the ones expected by the experimenter. Animal conditioning studies have shown, however, that the failure of CRs to emerge does not inevitably mean that the stimulus was ignored and an appropriate CR may appear if performance-related variables are manipulated. Similarly, humans may or may not show a CR and yet be able to verbalize correctly the contingency experienced during the conditioning. Thus for human Ss a cognitive expectancy measure should be able to reveal cue salience independent of the actual elaboration of a CR. We therefore repeated the Evans and Busch (1974) procedure and measured, instead of attitudinal changes to the CS, the Ss' perception of the contingency they had experienced.