Long-term response-stimulus associations can influence distractor-response bindings

Binding of the feature stimulus duration in the auditory domain: S-R or S-S binding; or both?

Perceiving and reacting to multidimensional objects creates so-called event files via feature binding. Bogon, Thomaschke, and Dreisbach provided the first evidence for the integration of the feature stimulus duration into such event files. However, their paradigm did not allow for differentiation between stimulus-stimulus and stimulus-response binding. This study used a classification task with many-to-one mappings to examine the integration of stimulus and response features independently. Experiment 1 used a pitch classification task. Participants had to respond with a left keypress to a low and a very low sine tone and with a right keypress to a high and very high sine tone. The four sine tones were presented for either a short or long duration, resulting in a total of eight stimuli. As an indicator of binding, we used partial repetition costs (better performance when both pitch/response and duration repeat or shift relative to partial repetitions). Results of Experiment 1 indicate stimulus-response binding and no stimulus-stimulus binding. In Experiment 2, instead of classifying the pitch of artificial sine tones, participants had to classify the type of musical instruments that produced the stimulus tones. Results replicated evidence for stimulus-response binding but also provided indications for stimulus-stimulus binding. Potential reasons for this result pattern and the relevance of duration in a musical context as one potential moderator of stimulus-stimulus bindings are discussed.

Binding time: Investigations on the integration of visual stimulus duration

The perception of and reaction to objects creates bindings of (object) features and responses, also called event files. In this context, time is a so far understudied feature. We conducted four experiments to investigate whether the duration of visual stimuli is also integrated into such event files. Experiments 1, 2, and 4 used a simple colour classification task and in Experiment 3 the location of a stimulus had to be classified. In all Experiments, the presentation duration of the stimuli (coloured circles) was either short (20 ms) or long (300 ms). We expected partial repetition costs as an indicator of binding. That is, performance should be better when both colour (Experiment 3: location) and duration repeat or alternate relative to partial repetitions. Results showed no partial repetition costs in Experiments 1 and 3, indicating no integration of duration into visual event files. Experiments 2 and 4 revealed partial repetition costs. Performance was better when Colour and Duration repeated compared with a partial repetition. What distinguishes the latter two experiments from the former is that the coloured stimuli could change their presentation location. The results of all four experiments show a pattern that duration can be integrated into visual event files depending on two criteria: The experimental context holds the possibility of a location change of the target stimulus (Experiments 2 and 4) and the location itself is not response relevant (Experiment 3). The role of location changes for the integration of temporal stimulus features into visual event files is discussed.

The official soundtrack to "Five shades of grey": Generalization in multimodal distractor-based retrieval

When responding to two events in a sequence, the repetition or change of stimuli and the accompanying response can benefit or interfere with response execution: Full repetition leads to benefits in performance while partial repetition leads to costs. Additionally, even distractor stimuli can be integrated with a response, and can, upon repetition, lead to benefits or interference. Recently it has been suggested that not only identical, but also perceptually similar distractors retrieve a previous response (Singh et al., Attention, Perception, & Psychophysics, 78(8), 2307-2312, 2016): Participants discriminated four visual shapes appearing in five different shades of grey, the latter being irrelevant for task execution. Exact distractor repetitions yielded the strongest distractor-based retrieval effect, which decreased with increasing dissimilarity between shades of grey. In the current study, we expand these findings by conceptually replicating Singh et al. (2016) using multimodal stimuli. In Experiment 1 (N=31), participants discriminated four visual targets accompanied by five auditory distractors. In Experiment 2 (N=32), participants discriminated four auditory targets accompanied by five visual distractors. We replicated the generalization of distractor-based retrieval - that is, the distractor-based retrieval effect decreased with increasing distractor-dissimilarity. These results not only show that generalization in distractor-based retrieval occurs in multimodal feature processing, but also that these processes can occur for distractors perceived in a different modality to that of the target.

David and Goliath-size does matter: size modulates feature-response binding of irrelevant features

Stimulus and response features are integrated together in episodic traces. A repetition of any of the features results in the retrieval of the entire episodic trace, including the response features. Such S-R bindings have been suggested to account for different priming effects like repetition priming, negative priming and so on. Previous studies on repetition priming have found priming effects to be size invariant. The present study examines whether the size invariance in previous priming studies was due to the absence of size-response binding. In two experiments, size was varied orthogonally to the response, either without varying any other stimulus features (Experiment 1) or while varying another stimulus feature (Experiment 2). A significant size-response binding effect was observed in Experiment 1 but not in Experiment 2. The results suggest that size is involved in feature-response binding and can retrieve the response upon repetition. However, this retrieval is extinguished if another stimulus feature is varied simultaneously. The results are discussed against the background of S-R binding as the mechanism underlying repetition priming.

Evidences for better recall of congruent items in episodic memory

A focus of recent research is to understand the role of our own response goals in the selection of information that will be encoded in episodic memory. For example, if we respond to a target in the presence of distractors, an important aspect under study is whether the distractor and the target share a common response (congruent) or not (incongruent). Some studies have found that congruent objects tend to be grouped together and stored in episodic memory, whereas other studies found that targets in the presence of incongruent distractors are remembered better. Our current research seems to support both views. We used a Tulving-based definition of episodic memory to differentiate memory from episodic and non-episodic traces. In this task, participants first had to classify a blue object as human or animal (target) which appeared in the presence of a green one (distractor) that could belong to the same category as the target (congruent); to the opposite one (incongruent); or to an irrelevant one (neutral). Later they had to report the identity (What), location (Where) and time (When) of both target objects (which had been previously responded to) and distractors (which had been ignored). Episodic memory was inferred when the three scene properties (identity, location and time) were correct. The measure of non-episodic memory consisted of those trials in which the identity was correctly remembered, but not the location or time. Our results show that episodic memory for congruent stimuli is significantly superior to that for incongruent ones. In sharp contrast, non-episodic measures found superior memory for targets in the presence of incongruent distractors. Our results demonstrate that response compatibility affects the encoding of episodic and non-episodic memory traces in different ways.

The Role of Congruency for Distractor-Response Binding: A Caveat

Responding in the presence of stimuli leads to an integration of stimulus features and response features into event files, which can later be retrieved to assist action control. This integration mechanism is not limited to target stimuli, but can also include distractors (distractor-response binding). A recurring research question is which factors determine whether or not distractors are integrated. One suggested candidate factor is target-distractor congruency: Distractor-response binding effects were reported to be stronger for congruent than for incongruent target-distractor pairs. Here, we discuss a general problem with including the factor of congruency in typical analyses used to study distractor-based binding effects. Integrating this factor leads to a confound that may explain any differences between distractor-response binding effects of congruent and incongruent distractors with a simple congruency effect. Simulation data confirmed this argument. We propose to interpret previous data cautiously and discuss potential avenues to circumvent this problem in the future.

The Law of Recency: An Episodic Stimulus-Response Retrieval Account of Habit Acquisition

A habit is a regularity in automatic responding to a specific situation. Classical learning psychology explains the emergence of habits by an extended learning history during which the response becomes associated to the situation (learning of stimulus-response associations) as a function of practice ("law of exercise") and/or reinforcement ("law of effect"). In this paper, we propose the "law of recency" as another route to habit acquisition that draws on episodic memory models of automatic response regulation. According to this account, habitual responding results from (a) storing stimulus-response episodes in memory, and (b) retrieving these episodes when encountering the stimulus again. This leads to a reactivation of the response that was bound to the stimulus (c) even in the absence of extended practice and reinforcement. As a measure of habit formation, we used a modified color-word contingency learning (CL) paradigm, in which irrelevant stimulus features (i.e., word meaning) were predictive of the to-be-executed color categorization response. The paradigm we developed allowed us to assess effects of global CL and of an instance-based episodic response retrieval simultaneously within the same experiment. Two experiments revealed robust CL as well as episodic response retrieval effects. Importantly, these effects were not independent: Controlling for response retrieval effects eliminated effects of CL, which supports the claim that habit formation can be mediated by episodic retrieval processes, and that short-term binding effects are not fundamentally separate from long-term learning processes. Our findings have theoretical and practical implications regarding (a) models of long-term learning, and (b) the emergence and change of habitual responding.

Dissecting stimulus-response binding effects: Grouping by color separately impacts integration and retrieval processes

In selection tasks, target and distractor features can be encoded together with the response into the same short-lived memory trace, or event file (see Hommel, 2004), leading to bindings between stimulus and response features. The repetition of a stored target or distractor feature can lead to the retrieval of the entire episode, including the response-so-called "binding effects." Binding effects due to distractor repetition are stronger for grouped than for nongrouped target and distractor stimulus configurations. Modulation of either of two mechanisms that lead to the observed binding effects might be responsible here: Grouping may influence either stimulus-response integration or stimulus-response retrieval. In the present study we investigated the influences of grouping on both mechanisms independently. In two experiments, target and distractor letters were grouped (or nongrouped) via color (dis)similarity separately during integration and retrieval. Grouping by color similarity affected integration and retrieval mechanisms independently and in different ways. Color dissimilarity enhanced distractor-based retrieval, whereas color similarity enhanced distractor integration. We concluded that stimulus grouping is relevant for binding effects, but that the mechanisms that contribute to binding effects should be carefully separated.

May I have your attention please: Binding of attended but response-irrelevant features

The feature codes of stimuli and responses can be integrated, and if a stimulus is repeated it can retrieve the previously integrated response. Furthermore, even irrelevant features can be integrated and, upon repetition, retrieve the response. Yet the role of attention in feature integration and retrieval is not clearly understood. Some theories assume a central role of attention (e.g., Logan, 1988; Treisman & Gelade, 1980), but other studies have shown no influence of attention on feature binding (e.g., Hommel, 2005). In the present experiments the effect of attention on the integration of two different response-irrelevant features of the same stimulus was examined. In two experiments, participants responded to the color (response feature) of word stimuli, while two irrelevant features of the words (word type and valence) were systematically varied. Participants' attention was directed to either one or the other of the response-irrelevant features by asking participants to report that feature at the end of the trial. Feature-response binding effects in the color task were observed to be stronger for the attended response-irrelevant feature. These results indicate that feature binding is not only very flexible but also sensitive to the distribution of attention. It is also automatic, in the sense that as long as attention is available, feature binding occurs irrespective of the task-specific demands.

Repetition priming in amnesia: Distinguishing associative learning at different levels of abstraction

Learned associations between stimuli and responses make important contributions to priming. The current study aimed to determine whether medial temporal lobe (MTL) binding mechanisms mediate this learning. Prior studies implicating the MTL in stimulus-response (S-R) learning have not isolated associative learning at the response level from associative learning at other levels of representation (e.g., task sets or decisions). The current study investigated whether the MTL is specifically involved in associative learning at the response level by testing a group of amnesic patients with MTL damage on a priming paradigm that isolates associative learning at the response level. Patients demonstrated intact priming when associative learning was isolated to the stimulus-response level. In contrast, their priming was reduced when associations between stimuli and more abstract representations (e.g., stimulus-task or stimulus-decision associations) could contribute to performance. These results provide novel neuropsychological evidence that S-R contributions to priming can be supported by regions outside the MTL, and suggest that the MTL may play a critical role in linking stimuli to more abstract tasks or decisions during priming.

Dissociation of binding and learning processes

A single encounter of a stimulus together with a response can result in a short-lived association between the stimulus and the response [sometimes called an event file, see Hommel, Müsseler, Aschersleben, & Prinz, (2001) Behavioral and Brain Sciences, 24, 910-926]. The repetition of stimulus-response pairings typically results in longer lasting learning effects indicating stimulus-response associations (e.g., Logan & Etherton, (1994) Journal of Experimental Psychology: Learning, Memory, and Cognition, 20, 1022-1050]. An important question is whether or not what has been described as stimulus-response binding in action control research is actually identical with an early stage of incidental learning (e.g., binding might be seen as single-trial learning). Here, we present evidence that short-lived binding effects can be distinguished from learning of longer lasting stimulus-response associations. In two experiments, participants always responded to centrally presented target letters that were flanked by response irrelevant distractor letters. Experiment 1 varied whether distractors flanked targets on the horizontal or vertical axis. Binding effects were larger for a horizontal than for a vertical distractor-target configuration, while stimulus configuration did not influence incidental learning of longer lasting stimulus-response associations. In Experiment 2, the duration of the interval between response n - 1 and presentation of display n (500 ms vs. 2000 ms) had opposing influences on binding and learning effects. Both experiments indicate that modulating factors influence stimulus-response binding and incidental learning effects in different ways. We conclude that distinct underlying processes should be assumed for binding and incidental learning effects.

On the efficiency of instruction-based rule encoding

Instructions have long been considered a highly efficient route to knowledge acquisition especially compared to trial-and-error learning. We aimed at substantiating this claim by identifying boundary conditions for such an efficiency gain, including the influence of active learning intention, repeated instructions, and working memory load and span. Our experimental design allowed us to not only assess how well the instructed stimulus-response (S-R) rules were implemented later on, but also to directly measure prior instruction encoding processes. This revealed that instruction encoding was boosted by an active learning intention which in turn entailed better subsequent rule implementation. As should be expected, instruction-based learning took fewer trials than trial-and-error learning to reach a similar performance level. But more importantly, even when performance was measured relative to the identical number of preceding correct implementation trials, this efficiency gain persisted both in accuracy and in speed. This suggests that the naturally greater number of failed attempts in the initial phase of trial-and-error learning also negatively impacted learning in subsequent trials due to the persistence of erroneous memory traces established beforehand. A single instruction trial was sufficient to establish the advantage over trial-and-error learning but repeated instructions were better. Strategic factors and inter-individual differences in WM span - the latter exclusively affecting trial-and-error learning presumably due to the considerably more demanding working memory operations - could reduce or even abolish this advantage, but only in error rates. The same was not true for response time gains suggesting generally more efficient task automatization in instruction-based learning.

A common mechanism behind distractor-response and response-effect binding?

Short-term bindings between responses and events in the environment ensure efficient behavioral control. This notion holds true for two particular types of binding: bindings between responses and response-irrelevant distractor stimuli that are present at the time of responding, and also for bindings between responses and the effects they cause. Although both types of binding have been extensively studied in the past, little is known about their interrelation. In three experiments, we analyzed both types of binding processes in a distractor-response binding design and in a response-effect binding design, which yielded two central findings: (1) Distractor-response binding and response-effect binding effects were observed not only in their native, but also in the corresponding "non-native" design, and (2) a manipulation of retrieval delay affected both types of bindings in a similar way. We suggest that a general and unselective mechanism is responsible for integrating own responses with a large variety of stimuli.

Binding abstract concepts

Binding theories assume that a stimulus and the response made to it are bound together in an event file (Hommel et al., Behav Brain Sci 24(05):849-937, 2001). Such bindings can occur even after single encounters. If the stimulus or parts of its features are repeated within the time frame in which the event file is still intact, the previously integrated response is retrieved. Stimulus-response binding can exist at a perceptual, conceptual or a response selection level (Henson et al., Trends Cogn Sci 18(7):376-384, 2014). The current experiments test whether the observed binding of concepts with responses can be extended from concrete to abstract concepts (detailedness) and whether abstract concepts can retrieve the previous response, in the absence of perceptual repetition. In the present experiment participants responded to a target feature (colour) while the detailedness of the stimulus was irrelevant to the task. The results showed a significant interaction of response relation and detailedness relation, even in the absence of perceptual repetition. This interaction is interpreted as evidence for response-retrieval due to abstract concept repetition. Thus, our data suggest a broader impact of binding mechanism on performance as even abstract concepts can be integrated into event-files and later modulate behaviour.

The effect of gamma-enhancing binaural beats on the control of feature bindings

Binaural beats represent the auditory experience of an oscillating sound that occurs when two sounds with neighboring frequencies are presented to one’s left and right ear separately. Binaural beats have been shown to impact information processing via their putative role in increasing neural synchronization. Recent studies of feature-repetition effects demonstrated interactions between perceptual features and action-related features: repeating only some, but not all features of a perception–action episode hinders performance. These partial-repetition (or binding) costs point to the existence of temporary episodic bindings (event files) that are automatically retrieved by repeating at least one of their features. Given that neural synchronization in the gamma band has been associated with visual feature bindings, we investigated whether the impact of binaural beats extends to the top-down control of feature bindings. Healthy adults listened to gamma-frequency (40 Hz) binaural beats or to a constant tone of 340 Hz (control condition) for ten minutes before and during a feature-repetition task. While the size of visuomotor binding costs (indicating the binding of visual and action features) was unaffected by the binaural beats, the size of visual feature binding costs (which refer to the binding between the two visual features) was considerably smaller during gamma-frequency binaural beats exposure than during the control condition. Our results suggest that binaural beats enhance selectivity in updating episodic memory traces and further strengthen the hypothesis that neural activity in the gamma band is critically associated with the control of feature binding.

Distractor-based stimulus-response bindings retrieve decisions independent of motor programs

Research on the distractor response binding (DRB) effect (Frings, Rothermund, & Wentura, 2007) suggests that distractors are integrated with target responses into an event file or stimulus-response (SR) episode. The whole event file is retrieved when the distractor is repeated and as a consequence distractors can retrieve previous responses. Nett, Bröder, and Frings (2015) argued that even decisions under uncertainty are integrated into event files and can later on be retrieved by distractors. However, their paradigm did not allow disentangling the retrieval of decisions from the retrieval of motor programs. Here we disentangled the retrieval of decisions and motor programs by assuring that retrieved decisions were not confounded by the repetitions of motor programs. In particular, in two experiments using a sequential prime-probe distractor priming task participants used other keys or other effectors for prime and probe responses; nevertheless repeated task-irrelevant distractors increased the probability that participants repeated the prime decision irrespective of motor programs. Thus, decision features can become part of an event-file and directly be retrieved by irrelevant information suggesting that bindings have an even higher flexibility and ubiquity than previously assumed.

The Effects of the Amount of Information on Episodic Memory Binding

The effects of increasing the number of items to be remembered on associative recognition and cued recall were examined. Thirty participants were asked during encoding to determine whether two- and three-item stimuli contained natural objects, artificial objects, or both. In an associative recognition task, the participants indicated whether the stimuli were identical to those presented during encoding, were rearranged by exchanging one of the two-item stimuli for one of the three-item stimuli, or represented a new stimulus. The correctly identified rearranged item pairs and triads were included in a subsequent cued-recall task in which participants verbally reported the missing item. As the number of items increased, the discrimination of rearranged stimuli diminished, but that of identical trials remained the same. Furthermore, the ability to retrieve the missing item was unaffected. It was concluded that the effect of the amount of information on binding depends on how the information must be retrieved.

Memory reconsolidation may be disrupted by a distractor stimulus presented during reactivation

Memories can be destabilized by the reexposure to the training context, and may reconsolidate into a modified engram. Reconsolidation relies on some particular molecular mechanisms involving LVGCCs and GluN2B-containing NMDARs. In this study we investigate the interference caused by the presence of a distractor - a brief, unanticipated stimulus that impair a fear memory expression - during the reactivation session, and tested the hypothesis that this disruptive effect relies on a reconsolidation process. Rats previously trained in the contextual fear conditioning (CFC) were reactivated in the presence or absence of a distractor stimulus. In the test, groups reactivated in the original context with distractor displayed a reduction of the freezing response lasting up to 20 days. To check for the involvement of destabilization / reconsolidation mechanisms, we studied the effect of systemic nimodipine (a L-VGCC blocker) or intra-CA1 ifenprodil (a selective GluN2B/NMDAR antagonist) infused right before the reactivation session. Both treatments were able to prevent the disruptive effect of distraction. Ifenprodil results also bolstered the case for hippocampus as the putative brain structure hosting this phenomenon. Our results provide some evidence in support of a behavioral, non-invasive procedure that was able to disrupt an aversive memory in a long-lasting way.