Are spatial selection and identity extraction separable when attention is controlled endogenously?

Visual search for a target involves two processes: spatial selection and identity extraction. Ghorashi, Enns, and Di Lollo (2008) found these processes to be independent and surmised that they were carried out along distinct visual pathways: dorsal and ventral, respectively. The two experiments that are described in the present article evaluated this hypothesis. Attentional-blink methodology was combined with voluntary spatial cuing in a visual search task: Intertarget lag was used to manipulate identity extraction; predictive cues were used to signal target locations. Central digit cues in Experiment 1 required participants to identify digits before voluntarily directing attention to a corresponding location, whereas flashed dots in Experiment 2 (indicating an opposite location) required attentional redeployment without prior cue identification. Consistent with the dual-pathway hypothesis, cuing was impaired only when the first target and the number cue competed for ventral-pathway mechanisms. Collectively, the results support the dual-pathway account of the separability of spatial selection and identity extraction.     

Evaluating the contributions of task expectancy in the testing and guessing benefits on recognition memory

Recently, we have shown that two types of initial testing (recall of a list or guessing of critical items repeated over 12 study/test cycles) improved final recognition of related and unrelated word lists relative to restudy. These benefits were eliminated, however, when test instructions were manipulated within subjects and presented after study of each list, procedures designed to minimise expectancy of a specific type of upcoming test [Huff, Balota, & Hutchison, 2016. The costs and benefits of testing and guessing on recognition memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 42, 1559–1572. doi:10.1037/xlm0000269], suggesting that testing and guessing effects may be influenced by encoding strategies specific for the type of upcoming task. We follow-up these experiments by examining test-expectancy processes in guessing and testing. Testing and guessing benefits over restudy were not found when test instructions were presented either after (Experiment 1) or before (Experiment 2) a single study/task cycle was completed, nor were benefits found when instructions were presented before study/task cycles and the task was repeated three times (Experiment 3). Testing and guessing benefits emerged only when instructions were presented before a study/task cycle and the task was repeated six times (Experiments 4A and 4B). These experiments demonstrate that initial testing and guessing can produce memory benefits in recognition, but only following substantial task repetitions which likely promote task-expectancy processes.     

Effects of binding in the identification of objects

The binding problem requires a solution at the level of individual neurons, but no definite mechanism has yet be given. Therefore, the neuronal level is as yet inadequate for modeling cognitive processes in which binding plays a crucial role. Moreover, the neuronal level involves too many details that are unlikely to be essential for understanding cognition. A general model of cognitive brain functioning is described in which cognitive tasks are represented in a network of cell assemblies. In the network, binding is functionally defined in a way that is compatible with the neuronal level. A computer simulation of the model clarifies how the binding of location and identity of a set of simultaneously presented letters takes place and how questions about the location and identity of the letters are answered. From the simulation of the task three predictions on the logistics of neural processes are derived: 1. When the cell assembly representing a letter participates in more than one temporary excitation loop, it will reach its critical threshold faster. At the behavioral level this means that as the number of identical letters in the display increases, responses will be faster. 2. In order to answer questions about the location and identity of presented letters cell assemblies representing the target location and the target identity have to become bound to their appropriate values. As a consequence the facilitatory effect of identical letters will be stronger if they involve the target location or the target identity than when identical non-targets are involved. 3. Negative identifications are more dependent on the presentation time of the letters than positive identifications because the excitation loops involved take more time to reach the critical threshold. Therefore, the facilitatory effect of identical letters is stronger when the external activation is relatively strong, i.e., when presentation time of the letters is sufficiently long. The reaction times obtained in three behavioral experiments support these hypotheses. Effects of binding can therefore be predicted on the basis of the general logistics of neural processes, without assumptions about a specific binding mechanism at the neuronal level.     

The effect of pre-cueing on spatial attention across perception and action

It is well established that processes of perception and action interact. A key question concerns the role of attention in the interaction between perception-action processes. We tested the hypothesis that spatial attention is shared by perception and action. We created a dual-task paradigm: In one task, spatial information is relevant for perception (spatial-input task) but not for action, and in a second task, spatial information is relevant for action (spatial-output task) but not for perception. We used endogenous pre-cueing, with two between-subjects conditions: In one condition the cue was predictive only for the target location in the spatial-input task; in a second condition the cue was predictive only for the location of the response in the spatial-output task. In both conditions, the cueing equally affected both tasks, regardless of the information conveyed by the cue. This finding directly supports the shared input-output attention hypothesis.     

Binding targets’ responses to distractors’ locations: Distractor response bindings in a location-priming task

Responses to target stimuli can be encoded together with distracting objects accompanying these targets into a single stimulus-response episode or a single event file. Repeating any object of such an episode can trigger the response encoded in this episode. Hence, repeating a distractor may retrieve the response given to the target that was accompanied by this distractor. In the present experiments, we analyzed whether the binding of target responses to the distractor can be generalized even to the location of a distractor. In two experiments, we used a location-based prime-probe task and found that repeating the location of a distractor triggered the response to the target that had previously been accompanied by a distractor in the repeated location, even if the identity of the distractor changed from the prime to the probe.     

Measuring facial identity and emotion integration using the redundancy gain paradigm

Early theories on face perception posit that invariant (i.e., identity) and changeable (i.e., expression) facial aspects are processed separately. However, many researchers have countered the hypothesis of parallel processes with findings of interactions between identity and emotion perception. The majority of tasks measuring interactions between identity and emotion employ a selective attention design, in which participants are instructed to attend to one dimension (e.g., identity) while the other dimension varies orthogonally (e.g., emotion), but is task irrelevant. Recently, a divided attention design (i.e., the redundancy gain paradigm) in which both identity and emotion are task relevant was employed to assess the interaction between identity and emotion. A redundancy gain is calculated by a drop in reaction time in trials in which a target from both dimensions is present in the stimulus face (e.g., “sad Person A”), compared with trials with only a single target present (e.g., “sad” or “Person A”). Redundancy gains are hypothesized to point to an interactive activation of both dimensions, and as such, could complement designs adopting a selective attention task. The initial aim of the current study was to reproduce the earlier findings with this paradigm on identity and emotion perception (Yankouskaya, Booth, & Humphreys, Attention, Perception, & Psychophysics, 74(8), 1692–1711, 2012), but our study failed to replicate the results. In a series of subtasks, multiple aspects of the design were manipulated separately in our goal to shed light on the factors that influence the redundancy gain effect in faces. A redundancy gain was eventually obtained after controlling for contingencies and stimulus presentation time.     

The "what" and "where" of object representations in infancy

Four-month-olds' memory for surface feature and location information was tested following brief occlusions. When the target objects were images of female faces or monochromatic asterisks infants showed increased looking times following a change in identity or color but not following a change in location or combinations of feature and location information. When the target objects were images of manipulable toys, the infants showed increased looking times following a change in location but not identity or the binding of location and identity information. This evidence is consistent with the idea that young infants are unable to maintain the information processed separately in both the dorsal and ventral visual streams during occlusions. Our results suggest that it is the target's affordance for action that determines whether the dorsal or ventral information is selectively maintained during occlusion.     

Feature binding in visual short term memory: A General Recognition Theory analysis

Creating and maintaining accurate bindings of elementary features (e.g., color and shape) in visual short-term memory (VSTM) is fundamental for veridical perception. How are low-level features bound in memory? The present work harnessed a multivariate model of perception – the General Recognition Theory (GRT) – to unravel the internal representations underlying feature binding in VSTM. On each trial, preview and target colored shapes were presented in succession, appearing in either repeated or altered spatial locations. Participants gave two same/different responses: one with respect to color and one with respect to shape. Converging GRT analyses on the accuracy confusion matrices provided substantial evidence for binding in the form of violations of perceptual independence at the level of the individual stimulus, such that positive correlations were obtained when both features repeated or alternated together, while negative correlations were obtained when one feature repeated and the other alternated. This “cloverleaf” GRT pattern of binding was similar whether the spatial location of the preview and target repeated or altered. The current results are consistent with: (a) the discrete memory “slots” model of VSTM, and (b) the notion that spatial location is not necessary for the formation of “object files.” The GRT approach presented here offers a viable quantitative model for testing various questions regarding feature binding in VSTM.     

What makes recognition without awareness appear to be elusive? Strategic factors that influence the accuracy of guesses

Various factors could conceivably promote the accuracy of guesses during a recognition test. Two that we identified in previous studies are forced-choice testing format and high perceptual similarity between the repeat target and novel foil. In restricted circumstances, the relative perceptual fluency of the target can be compared with that of the foil and used as a reliable cue to guide accurate responses that occur without explicit retrieval—a phenomenon we referred to as “implicit recognition.” In this issue, Jeneson and colleagues report a failure to replicate accurate guesses and also a tendency on the part of subjects to hazard guesses infrequently, even though testing circumstances were very similar to those that we used. To resolve this discrepancy, we developed a simple manipulation to encourage either guessing or confident responding. Encouraging guessing increased both the prevalence of guesses and the accuracy of guesses in a recognition test, relative to when confident responding was encouraged. When guessing was encouraged, guesses were highly accurate (as in our previous demonstrations of implicit recognition), whereas when confident responding was encouraged, guesses were at chance levels (as in Jeneson and colleagues'' data). In light of a substantial literature showing high accuracy despite low confidence in certain circumstances, we infer that both the prevalence and accuracy of guessing can be influenced by whether subjects adopt guessing-friendly strategies. Our findings thus help to further characterize conditions likely to promote implicit recognition based on perceptual fluency.In several prior experiments, we reported findings indicative of recognition without awareness (Voss et al. 2008; Voss and Paller 2009). The experiments involved recognition tests for colorful and complex geometric shapes (kaleidoscope images). Subjects attempted to discriminate repeat stimuli (targets) from novel stimuli (foils). In some of our experiments, subjects made recognition responses and also rated the quality of their recognition experience or their confidence in their decision. For example, recognition often occurred with awareness of memory retrieval and with some level of confidence. On the other hand, correct recognition of a target sometimes occurred with no discernable awareness of memory retrieval or confidence; essentially, subjects felt that their response was merely a guess—and yet they were correct.Of course, the reason that a guess might be correct in a recognition test might have nothing at all to do with the subject having retrieved relevant information; the response might be merely a “lucky guess.” Our results, however, provided evidence that processes of implicit memory were operative in producing at least a subset of the correct guesses. In recognition tests using a forced-choice format, targets and foils shared a high degree of perceptual similarity and were displayed side-by-side, and we found that, for guess responses, the repeat stimulus was correctly selected remarkably often. With no stored information (and given that the target occurred equally often on the left side and the right side, and that targets and foils were counterbalanced across subjects), the repeat stimulus should be selected correctly 50% of the time in the long run. In our original report, we found that 82% of the guess responses were correct, which was more accurate than responses when trials with high- or low-confidence responses were pooled together (56%; data combined for all study conditions) (Experiment 2 of Voss et al. 2008). We referred to this phenomenon as recognition without awareness or implicit recognition. For the present discussion, we will use the latter term.Indeed, our results provided several additional reasons for linking implicit memory with this phenomenon of implicit recognition. In one experiment, each trial was classified as either (1) a recognition experience in which subjects recollected episodic information from their initial experience with the target; (2) recognition with familiarity for the target, but no other recall of prior information concerning the target; or (3) a guess with no confidence in the accuracy of the response (Voss and Paller 2009). We found that guesses were approximately as accurate as recollection responses (73% vs. 79%, respectively, averaged across encoding conditions), and that guesses were more accurate than decisions based on familiarity (59%, averaged across encoding conditions).Another feature of these experiments was that we contrasted two types of learning conditions. In one condition, to-be-remembered stimuli were viewed while subjects simultaneously performed a verbal working memory task. This task required that the subject listen to a spoken digit on each trial and respond according to whether the digit on the prior trial was odd or even (i.e., a one-back task). In the other condition, there were no spoken digits, and attention could be allocated fully to viewing the to-be-remembered stimuli. In several different experiments, recognition accuracy was higher with divided-attention study than with full-attention study. Although this is a highly unusual outcome for recognition performance, it was clear that divided attention during the study led to relatively less confidence during the recognition test, such that guessing was more prevalent, and these guess responses were highly accurate.Notably, these two key results—highly accurate guessing, and a recognition advantage for divided over full attention at study—were not obtained when recognition was tested with a yes–no format (targets and highly similar foils randomly intermixed and shown one stimulus at a time), or when a forced-choice test was prepared such that each target was paired with a random foil rather than a highly similar foil (Voss et al. 2008). On the basis of these findings, as well as additional results from electrophysiological recordings (described below in the Discussion section), we argued that subjects were able to weigh the relative perceptual fluency of the target and the foil only for forced-choice tests with high target/foil similarity, and then they could use this fluency cue to guide accurate selection of the target (Voss and Paller 2009).We aim to develop a line of reasoning to clarify why implicit recognition might tend to operate preferentially in certain circumstances, such as when the relative perceptual fluency of targets versus foils is likely to serve as a useful cue, and when the ability to remember specific stimulus details does not provide a useful cue (as is the case when these details are largely shared between the target and the foil). In many situations, however, perceptual fluency may not be a good basis for making recognition judgments. Often, accurate recognition reflects conceptual elaboration about the meaning of an event, and the conceptual features are typically remembered more robustly than the set of stimulus features perceived during the course of the event. Thus, implicit recognition may be less likely to guide a response in a recognition test in the presence of confident memory for the target. Dividing attention during encoding resulted in lower confidence during the recognition test, and this may have been one factor that promoted reliance on signals of relative perceptual fluency. Of course, there may be other factors that also promote or inhibit this type of strategy in a recognition test.     

Threat to Parental Role: A Possible Mechanism of Altered Self-Concept Related to Carrier Knowledge

Researchers and clinicians have suggested that learning one is a carrier for a genetic disorder has the potential to alter self-concept. Concerns about self-concept have influenced the development of policies regarding the availability of carrier testing for minors and the informed-consent process. A literature review identified three mechanisms through which self-concept has been proposed to be affected: altered perception of genetic identity, diminished social identity, and an altered perception of health. This paper presents a conceptual framework developed from identity theory and the self's response to threat to propose a fourth mechanism: threat to the parental role. Clarification of the role of self-concept, the threat to self-concept related to carrier knowledge, and coping behaviors activated in response to this threat would help to target appropriate genetic counseling interventions.     

Implicitly learned suppression of irrelevant spatial locations

How do we ignore a salient, irrelevant stimulus whose location is predictable? A variety of studies using instructional manipulations have shown that participants possess the capacity to exert location-based suppression. However, for the visual search challenges we face in daily life, we are not often provided explicit instructions and are unlikely to consciously deliberate on what our best strategy might be. Instead, we might rely on our past experience—in the form of implicit learning—to exert strategic control. In this paper, we tested whether implicit learning could drive spatial suppression. In Experiment 1, participants searched displays in which one location contained a target, while another contained a salient distractor. An arrow cue pointed to the target location with 70 % validity. Also, unbeknownst to the participants, the same arrow cue predicted the distractor location with 70 % validity. Results showed facilitated RTs to the predicted target location, confirming target enhancement. Critically, distractor interference was reduced at the predicted distractor location, revealing that participants used spatial suppression. Further, we found that participants had no explicit knowledge of the cue-distractor contingencies, confirming that the learning was implicit. In Experiment 2, to seek further evidence for suppression, we modified the task to include occasional masked probes following the arrow cue; we found worse probe identification accuracy at the predicted distractor location than control locations, providing converging evidence that observers spatially suppressed the predicted distractor locations. These results reveal an ecologically desirable mechanism of suppression, which functions without the need for conscious knowledge or externally guided instructions.     

Location negative priming in identity discrimination relies on location repetition

Negative priming manifests when a previously ignored stimulus becomes a target. The contingency of identity negative priming on repeated stimuli has been demonstrated, implying a crucial role for distractor competition. In this study, a naming task was used to examine whether location negative priming also relies on the repetition of locations. In Experiment 1, location negative priming was observed only when a small set of repeated locations was used. Positive priming was found instead when a large set of nonrepeated locations was used. Experiment 2 demonstrated that target-to-distractor distance modulated location priming effects, with priming effects observed only for a far distance. Experiments 3 and 4 demonstrated that the effect of location negative priming increased as locations repeated. Like identity negative priming, location negative priming depends on location repetition.     

Saccade latency reveals episodic representation of object color

While previous studies suggest that identity, but not color, plays a role in episodic object representation, such studies have typically used tasks in which only identity is relevant, raising the possibility that the results reflect task demands, rather than the general principles that underlie object representation. In the present study, participants viewed a preview display containing one (Experiments 1 and 2) or two (Experiment 3) letters, then viewed a target display containing a single letter, in either the same or a different location. Participants executed an immediate saccade to fixate the target; saccade latency served as the dependent variable. In all experiments, saccade latencies were longer to fixate a target appearing in its previewed location, consistent with a bias to attend to new objects rather than to objects for which episodic representations are being maintained in visual working memory. The results of Experiment 3 further demonstrate, however, that changing target color eliminates these latency differences. The results suggest that color and identity are part of episodic representation even when not task relevant and that examining biases in saccade execution may be a useful approach to studying episodic representation.     

Spatial and identity negative priming in audition: Evidence of feature binding in auditory spatial memory

Two experiments are reported with identical auditory stimulation in three-dimensional space but with different instructions. Participants localized a cued sound (Experiment 1) or identified a sound at a cued location (Experiment 2). A distractor sound at another location had to be ignored. The prime distractor and the probe target sound were manipulated with respect to sound identity (repeated vs. changed) and location (repeated vs. changed). The localization task revealed a symmetric pattern of partial repetition costs: Participants were impaired on trials with identity-location mismatches between the prime distractor and probe target-that is, when either the sound was repeated but not the location or vice versa. The identification task revealed an asymmetric pattern of partial repetition costs: Responding was slowed down when the prime distractor sound was repeated as the probe target, but at another location; identity changes at the same location were not impaired. Additionally, there was evidence of retrieval of incompatible prime responses in the identification task. It is concluded that feature binding of auditory prime distractor information takes place regardless of whether the task is to identify or locate a sound. Instructions determine the kind of identity-location mismatch that is detected. Identity information predominates over location information in auditory memory.     

Visuospatial perceptual sequence learning and eye movements

We examined perceptual sequence learning by means of an adapted serial reaction time task in which eye movements were unnecessary for performing the sequence learning task. Participants had to respond to the identity of a target letter pair ("OX" or "XO") appearing in one of four locations. On the other locations, similar distractor letter pairs ("QY" or "YQ") were shown. While target identity changed randomly, target location was structured according to a deterministic sequence. To render eye movements superfluous, (1) stimulus letter pairs appeared around a fixation cross with a visual angle of 0.63°, which means that they appeared within the foveal visual area and (2) the letter pairs were presented for only 100 ms, a period too short to allow proper eye movements. Reliable sequence knowledge was acquired under these conditions, as responses were both slower and less accurate when the trained sequence was replaced by an untrained sequence. These results support the notion that perceptual sequence learning can be based on shifts of attention without overt oculomotor movements.     

Reflexive orienting by central arrows: Evidence from the inattentional blindness task

It was demonstrated that central arrows produce orienting of attention even when they are nonpredictive as to the target location. This finding was suggested to indicate reflexive orienting of attention by central arrows. However, it is not clear whether central arrows can produce an attentional effect without awareness. In two experiments, using a variation of the inattentional blindness task, we examine whether orienting of attention by a central arrow can be demonstrated without conscious perception of the arrow. We found that attention could be directed to the cued location even when the arrow was not consciously perceived.     

Object-location binding across a saccade: A retinotopic spatial congruency bias

Despite frequent eye movements that rapidly shift the locations of objects on our retinas, our visual system creates a stable perception of the world. To do this, it must convert eye-centered (retinotopic) input to world-centered (spatiotopic) percepts. Moreover, for successful behavior we must also incorporate information about object features/identities during this updating – a fundamental challenge that remains to be understood. Here we adapted a recent behavioral paradigm, the “spatial congruency bias,” to investigate object-location binding across an eye movement. In two initial baseline experiments, we showed that the spatial congruency bias was present for both gabor and face stimuli in addition to the object stimuli used in the original paradigm. Then, across three main experiments, we found the bias was preserved across an eye movement, but only in retinotopic coordinates: Subjects were more likely to perceive two stimuli as having the same features/identity when they were presented in the same retinotopic location. Strikingly, there was no evidence of location binding in the more ecologically relevant spatiotopic (world-centered) coordinates; the reference frame did not update to spatiotopic even at longer post-saccade delays, nor did it transition to spatiotopic with more complex stimuli (gabors, shapes, and faces all showed a retinotopic congruency bias). Our results suggest that object-location binding may be tied to retinotopic coordinates, and that it may need to be re-established following each eye movement rather than being automatically updated to spatiotopic coordinates.     

Continuous flash suppression and monocular pattern masking impact subjective awareness similarly

Peters and Lau (eLife, 4, e09651, 2015) found that when criterion bias is controlled for, there is no evidence for unconscious visual perception in normal observers, in the sense that they cannot directly discriminate a target above chance without knowing it. One criticism of that study is that the visual suppression method used, forward and backward masking (FBM), may be too blunt in the way it interferes with visual processing to allow for unconscious forced-choice discrimination. To investigate this question, we compared FBM directly to continuous flash suppression (CFS) in a two-interval forced-choice task. Although CFS is popular, and may be thought of as a more powerful visual suppression technique, we found no difference in the degree of perceptual impairment between the two suppression types. To the extent that CFS impairs perception, both objective discrimination and subjective awareness are impaired to similar degrees under FBM. This pattern was consistently observed across three experiments in which various experimental parameters were varied. These findings provide evidence for an ongoing debate about unconscious perception: normal observers cannot perform forced-choice discrimination tasks unconsciously.     

The effects of payoffs and prior probabilities on indices of performance and cutoff location in recognition memory

We compared the effects of payoffs and prior probability levels on indices of performance and cutoff location in recognition memory. The performance indices considered were d’ from signal-detection theory and two corrections for guessing from simple threshold models. Shifts in cutoff location of comparable size were found for changes in priors and payoffs. The existence of a memory load and the inclusion of feedback did not affect the extent of shifts in cutoff location. Priors affected the corrections for guessing but did not affect d’. These results indicate that d’ remains the preferred index of performance and that the corrections for guessing are not criterion-free measures. The problem of finding an index of recognition performance appropriate for comparing recall and recognition is discussed, as are alternative explanations for conservative cutoff placement.     

Visual memory for feature bindings: The disruptive effect of responding to new perceptual input

In the current study, we examined how short-term memory for location–identity feature bindings is influenced by subsequent cognitive and perceptual processing demands. Previous work has shown that memory performance for feature bindings can be disrupted by the presentation of subsequent visual information, particularly when this information is similar to that held in memory. The present study demonstrates that memory performance for feature bindings can be profoundly disrupted by also requiring a response to visual information presented subsequent to the visual memory array. Across five experiments, memory for a location–identity binding was substantially impaired following a localization response to a following item that matched the location but mismatched the identity of the memory target. The results point to an important role for action in the episodic integration processes that control short-term visual memory performance.