Categorical implicit learning in real-world scenes: evidence from contextual cueing

The present study examined the extent to which learning mechanisms are deployed on semantic-categorical regularities during a visual searching within real-world scenes. The contextual cueing paradigm was used with photographs of indoor scenes in which the semantic category did or did not predict the target position on the screen. No evidence of a facilitation effect was observed in the predictive condition compared to the nonpredictive condition when participants were merely instructed to search for a target T or L (Experiment 1). However, a rapid contextual cueing effect occurred when each display containing the search target was preceded by a preview of the scene on which participants had to make a decision regarding the scene's category (Experiment 2). A follow-up explicit memory task indicated that this benefit resulted from implicit learning. Similar implicit contextual cueing effects were also obtained when the scene to categorize was different from the subsequent search scene (Experiment 3) and when a mere preview of the search scene preceded the visual searching (Experiment 4). These results suggested that if enhancing the processing of the scene was required with the present material, such implicit semantic learning can nevertheless take place when the category is task irrelevant.     

Integrating spatial context learning over contradictory signals: Recency effects in contextual cueing

Contextual cueing is a visual search phenomenon in which memory of global visual context guides spatial attention towards task-relevant portions of the search display. Recent work has shown that the learning processes underlying contextual cueing exhibit primacy effects; they are more sensitive to early experience than to later experience. These results appear to pose difficulties for associative accounts which typically predict recency effects; behaviour being most strongly influenced by recent experience. The current study utilizes trial sequences that consist of two contradictory sets of regularities. In contrast to previous results, robust recency effects were observed. In a second study it is demonstrated that this recency effect can be minimized, but not reversed by systematically manipulating task-irrelevant features of the search display. These results provide additional support for an associative account of contextual cueing and suggest that contextual cueing may, under some circumstances, be more sensitive to recent experience.     

Intertrial interval as a contextual stimulus: further analysis of a novel asymmetry in temporal discrimination learning

Four experiments investigated discrimination learning when the duration of the intertrial interval (ITI) signaled whether or not the next conditional stimulus (CS) would be paired with food pellets. Rats received presentations of a 10-s CS separated half the time by long ITIs and half the time by short ITIs. When the long ITI signaled that the CS would be reinforced and the short interval signaled that it would not be (Long+/Short-), rats learned the discrimination readily. However, when the short ITI signaled that the CS would be reinforced and the long interval signaled that it would not (Short+/Long-), discrimination learning was much slower. Experiment 1 compared Long+/Short- and Short+/Long- discrimination learning with 16-min/4-min or 4-min/1-min ITI combinations. Experiment 2 found no evidence that Short+/Long- learning is inferior because the temporal cue corresponding to the short interval is ambiguous. Experiment 3 found no evidence that Short+/Long- learning is poor because the end of a long ITI signals a substantial reduction in delay to the next reinforcer. Long+/Short- learning may be faster than Short+/Long-because elapsing time involves exposure to a sequence of hypothetical stimulus elements (e.g., A then B), and feature-positive discriminations (AB+/A-) are learned quicker than feature-negative discriminations (A+/AB-). Consistent with this view, Experiment 4 found a robust feature-positive effect when sequentially presented CSs played the role of elements A and B.     

Testing the limits of statistical learning for word segmentation

Past research has demonstrated that infants can rapidly extract syllable distribution information from an artificial language and use this knowledge to infer likely word boundaries in speech. However, artificial languages are extremely simplified with respect to natural language. In this study, we ask whether infants’ ability to track transitional probabilities between syllables in an artificial language can scale up to the challenge of natural language. We do so by testing both 5.5‐ and 8‐month‐olds’ ability to segment an artificial language containing four words of uniform length (all CVCV) or four words of varying length (two CVCV, two CVCVCV). The transitional probability cues to word boundaries were held equal across the two languages. Both age groups segmented the language containing words of uniform length, demonstrating that even 5.5‐month‐olds are extremely sensitive to the conditional probabilities in their environment. However, neither age group succeeded in segmenting the language containing words of varying length, despite the fact that the transitional probability cues defining word boundaries were equally strong in the two languages. We conclude that infants’ statistical learning abilities may not be as robust as earlier studies have suggested.     

Time to guide: Evidence for delayed attentional guidance in contextual cueing

Contextual cueing experiments show that, when displays are repeated, reaction times (RTs) to find a target decrease over time even when the observers are not aware of the repetition. Recent evidence suggests that this benefit in standard contextual cueing tasks is not likely to be due to an improvement in attentional guidance (Kunar, Flusberg, Horowitz, & Wolfe, 2007). Nevertheless, we ask whether guidance can help participants find the target in a repeated display, if they are given sufficient time to encode the display. In Experiment 1 we increased the display complexity so that it took participants longer to find the target. Here we found a larger effect of guidance than in a condition with shorter RTs. Experiment 2 gave participants prior exposure to the display context. The data again showed that with more time participants could implement guidance to help find the target, provided that there was something in the search stimuli locations to guide attention to. The data suggest that, although the benefit in a standard contextual cueing task is unlikely to be a result of guidance, guidance can play a role if it is given time to develop.     

Invited commentary: Differential learning is different from contextual interference learning

There has been renewed interest in the detailed structure of what is learned and the boundary conditions that foster motor learning. The accompanying article by Hossner et al. (2016), particularly their findings about augmented feedback in the context of different levels of additional noise, is consistent with this focus. Unfortunately, the findings from Hossner and colleagues appear to be based on incorrect interpretations of the differential learning (DL) approach. Essential discrepancies in the experimental conditions suggest the basis for the deviating results obtained in comparison to those of the original DL experiments. In this comment, it is also shown that the author’s assumptions and interpretations underlying CI and the DL approaches obscure crucial problems and contradictions of classical learning theory.     

When being narrow minded is a good thing: Locally biased people show stronger contextual cueing

Repeated contexts allow us to find relevant information more easily. Learning such contexts has been proposed to depend upon either global processing of the repeated contexts, or alternatively processing of the local region surrounding the target information. In this study, we measured the extent to which observers were by default biased to process towards a more global or local level. The findings showed that the ability to use context to help guide their search was strongly related to an observer's local/global processing bias. Locally biased people could use context to help improve their search better than globally biased people. The results suggest that the extent to which context can be used depends crucially on the observer's attentional bias and thus also to factors and influences that can change this bias.     

Hippocampal differentiation without recognition: an fMRI analysis of the contextual cueing task

A central role of the hippocampus is to consolidate conscious forms of learning and memory, while performance on implicit tasks appears to depend upon other structures. Recently, considerable debate has emerged about whether hippocampal-dependent tasks necessarily entail task awareness. In the contextual cueing task, repetition facilitation is implicit, but impaired in patients with amnesia. Whether the hippocampus alone or other MTL structures are required is unclear. Event-related functional magnetic resonance imaging revealed hippocampal activity that differentiates novel from repeated arrays. This pattern of results was observed without recognition of the repeating arrays. This finding provides support for the claim that the hippocampus is involved in processes outside the domain of conscious learning and memory.     

Independence of long-term contextual memory and short-term perceptual hypotheses: Evidence from contextual cueing of interrupted search

Observers are able to resume an interrupted search trial faster relative to responding to a new, unseen display. This finding of rapid resumption is attributed to short-term perceptual hypotheses generated on the current look and confirmed upon subsequent looks at the same display. It has been suggested that the contents of perceptual hypotheses are similar to those of other forms of memory acquired long-term through repeated exposure to the same search displays over the course of several trials, that is, the memory supporting “contextual cueing.” In three experiments, we investigated the relationship between short-term perceptual hypotheses and long-term contextual memory. The results indicated that long-term, contextual memory of repeated displays neither affected the generation nor the confirmation of short-term perceptual hypotheses for these displays. Furthermore, the analysis of eye movements suggests that long-term memory provides an initial benefit in guiding attention to the target, whereas in subsequent looks guidance is entirely based on short-term perceptual hypotheses. Overall, the results reveal a picture of both long- and short-term memory contributing to reliable performance gains in interrupted search, while exerting their effects in an independent manner.     

Instrumental to Pavlovian transfer: Learning about response-reinforcer contingencies affects subsequent learning about stimulus-reinforcer contingencies

Two experiments examined the interaction between response-reinforcer (R-S) and stimulus-reinforcer (S-S) learning. In both experiments, three groups of rats were exposed to escapable, yoked inescapable, or no shocks. All groups were then exposed to either two or four sessions of truly random control (TRC) conditioning (Experiment 1) or to an excitatory conditioning procedure (Experiment 2) in which the shock US occurred with either moderate or low probability. Excitatory strength of the CS was assessed during extinction by a conditioned emotional response (CER) test. Inescapably shocked rats conditioned less than did their escapably shocked and nonshocked partners under all TRC conditions of Experiment 1, but only conditioned less than their partners in Experiment 2 when exposed to the moderate CS-US contingency for four sessions. These results provide a clear demonstration of transfer between instrumental training and Pavlovian excitatory conditioning and thus, support the influence of learning about R-S contingencies upon subsequent learning about S-S contingencies. Both a contextual blocking interpretation and an expansion of the learned helplessness theory were discussed as possible explanations of this transfer.     

Reward modulation of contextual cueing: Repeated context overshadows repeated target location

Contextual cueing can be enhanced by reward. However, there is a debate if reward is associated with the repeated target–distractor configurations or with the repeated target locations that occur in both repeated and new displays. Based on neuroimaging evidence, we hypothesized that reward becomes associated with the target location only in new displays, but not in repeated displays, where the repeated target location is overshadowed by the more salient repeated target–distractor configuration. To test this hypothesis, we varied the reward value associated with the same target location in repeated and new displays. The results confirmed the overshadowing hypothesis in that search facilitation in repeated target–distractor configurations was modulated by the variable value associated with the target location. This effect was observed mainly in early learning.     

The role of meaning in contextual cueing: Evidence from chess expertise

In contextual cueing, the position of a search target is learned over repeated exposures to a visual display. The strength of this effect varies across stimulus types. For example, real-world scene contexts give rise to larger search benefits than contexts composed of letters or shapes. We investigated whether such differences in learning can be at least partially explained by the degree of semantic meaning associated with a context independently of the nature of the visual information available (which also varies across stimulus types). Chess boards served as the learning context as their meaningfulness depends on the observer's knowledge of the game. In Experiment 1, boards depicted actual game play, and search benefits for repeated boards were 4 times greater for experts than for novices. In Experiment 2, search benefits among experts were halved when less meaningful randomly generated boards were used. Thus, stimulus meaningfulness independently contributes to learning context–target associations.     

The role of meaning in contextual cueing: evidence from chess expertise

In contextual cueing, the position of a search target is learned over repeated exposures to a visual display. The strength of this effect varies across stimulus types. For example, real-world scene contexts give rise to larger search benefits than contexts composed of letters or shapes. We investigated whether such differences in learning can be at least partially explained by the degree of semantic meaning associated with a context independently of the nature of the visual information available (which also varies across stimulus types). Chess boards served as the learning context as their meaningfulness depends on the observer's knowledge of the game. In Experiment 1, boards depicted actual game play, and search benefits for repeated boards were 4 times greater for experts than for novices. In Experiment 2, search benefits among experts were halved when less meaningful randomly generated boards were used. Thus, stimulus meaningfulness independently contributes to learning context-target associations.     

Two (or three) is one too many: testing the flexibility of contextual cueing with multiple target locations

Visual search for a target object is facilitated when the object is repeatedly presented within an invariant context of surrounding items ("contextual cueing"; Chun & Jiang, Cognitive Psychology, 36, 28-71, 1998). The present study investigated whether such invariant contexts can cue more than one target location. In a series of three experiments, we showed that contextual cueing is significantly reduced when invariant contexts are paired with two rather than one possible target location, whereas no contextual cueing occurs with three distinct target locations. Closer data inspection revealed that one "dominant" target always exhibited substantially more contextual cueing than did the other, "minor" target(s), which caused negative contextual-cueing effects. However, minor targets could benefit from the invariant context when they were spatially close to the dominant target. In sum, our experiments suggest that contextual cueing can guide visual attention to a spatially limited region of the display, only enhancing the detection of targets presented inside that region.     

Attention modulates the learning of multiple contingencies

We employed a novel version of the serial reaction time task to test the idea that human implicit learning allows the simultaneous learning of multiple independent contingencies and that this learning may proceed in the absence of attention. Using probabilistic sequences, we showed that both a primary sequence (the focus of the experimental task) and a statistically independent secondary sequence could be learned across 4,800 target localization trials, provided the perceptual load of the primary task was low. However, learning of the secondary sequence was abolished under conditions of high perceptual load. These findings suggest that there are attentional limitations on the learning of multiple contingencies.     

On the cognitive processes underlying contextual interference and observational learning

The main goal of the present study was to determine whether observation of an unskilled model learning a timing task enables the observer to develop a cognitive representation of the task similar to the one acquired through physical practice (Adams, 1986; Bandura, 1977; Lee & White, 1990). To reach that goal, we tested whether a contextual interference effect would be obtained in a retention test of subjects who had observed an individual practicing three variations of a timing task under a random or a blocked schedule of practice. Similar patterns of results in an immediate retention test were found following observation and physical practice. This suggests that observation indeed engaged the observers in the same type of cognitive activities as did physical practice. Moreover, a schedule of practice made up of 100% physical practice led to improved learning compared with a schedule of practice made up of 50% observation followed by 50% physical practice. This suggests that learning is enhanced more by numerous implementations of a motor program than by its mere construction or retrieval.     

Implicit statistical learning in language processing: Word predictability is the key

Fundamental learning abilities related to the implicit encoding of sequential structure have been postulated to underlie language acquisition and processing. However, there is very little direct evidence to date supporting such a link between implicit statistical learning and language. In three experiments using novel methods of assessing implicit learning and language abilities, we show that sensitivity to sequential structure – as measured by improvements to immediate memory span for structurally-consistent input sequences – is significantly correlated with the ability to use knowledge of word predictability to aid speech perception under degraded listening conditions. Importantly, the association remained even after controlling for participant performance on other cognitive tasks, including short-term and working memory, intelligence, attention and inhibition, and vocabulary knowledge. Thus, the evidence suggests that implicit learning abilities are essential for acquiring long-term knowledge of the sequential structure of language – i.e., knowledge of word predictability – and that individual differences on such abilities impact speech perception in everyday situations. These findings provide a new theoretical rationale linking basic learning phenomena to specific aspects of spoken language processing in adults, and may furthermore indicate new fruitful directions for investigating both typical and atypical language development.     

A configural dominant account of contextual cueing: Configural cues are stronger than colour cues

Previous work has shown that reaction times to find a target in displays that have been repeated are faster than those for displays that have never been seen before. This learning effect, termed “contextual cueing” (CC), has been shown using contexts such as the configuration of the distractors in the display and the background colour. However, it is not clear how these two contexts interact to facilitate search. We investigated this here by comparing the strengths of these two cues when they appeared together. In Experiment 1, participants searched for a target that was cued by both colour and distractor configural cues, compared with when the target was only predicted by configural information. The results showed that the addition of a colour cue did not increase contextual cueing. In Experiment 2, participants searched for a target that was cued by both colour and distractor configuration compared with when the target was only cued by colour. The results showed that adding a predictive configural cue led to a stronger CC benefit. Experiments 3 and 4 tested the disruptive effects of removing either a learned colour cue or a learned configural cue and whether there was cue competition when colour and configural cues were presented together. Removing the configural cue was more disruptive to CC than removing colour, and configural learning was shown to overshadow the learning of colour cues. The data support a configural dominant account of CC, where configural cues act as the stronger cue in comparison to colour when they are presented together.     

Implicit statistical learning is directly associated with the acquisition of syntax

This article reports on an individual differences study that investigated the role of implicit statistical learning in the acquisition of syntax in children. One hundred children ages 4 years 5 months through 6 years 11 months completed a test of implicit statistical learning, a test of explicit declarative learning, and standardized tests of verbal and nonverbal ability. They also completed a syntactic priming task, which provided a dynamic index of children's facility to detect and respond to changes in the input frequency of linguistic structure. The results showed that implicit statistical learning ability was directly associated with the long-term maintenance of the primed structure. The results constitute the first empirical demonstration of a direct association between implicit statistical learning and syntactic acquisition in children.