Attention, Perception, & Psychophysics

Sequence-dependent sensitivity explains the accuracy of decisions when cues are separated with a gap Abstract Most decisions require information gathering from a stimulus presented with different gaps. However, the neural mechanism underlying this integration is ambiguous. Recently, it has been claimed that humans can optimally integrate the information of two discrete pulses independent of the temporal gap between them. Interestingly, subjects’ performance on such a task, with two discrete pulses, is superior to what a perfect accumulator can predict. Although numerous neuronal and descriptive models have been proposed to explain the mechanism of perceptual decision-making, none can explain human behavior on this two-pulse task. In order to investigate the mechanism of decision-making on the noted tasks, a set of modified drift-diffusion models based on different hypotheses were used. Model comparisons clarified that, in a sequence of information arriving at different times, the accumulated information of earlier evidence affects the process of information accumulation of later evidence. It was shown that the rate of information extraction depends on whether the pulse is the first or the second one. Moreover, our findings suggest that a drift diffusion model with a dynamic drift rate can also explain the stronger effect of the second pulse on decisions as shown by Kiani et al. (Journal of Neuroscience, 33 (42), 16483-16489, 2013).

How the deployment of visual attention modulates auditory distraction Abstract Classically, attentional selectivity has been conceptualized as a passive by-product of capacity limits on stimulus processing. Here, we examine the role of more active cognitive control processes in attentional selectivity, focusing on how distraction from task-irrelevant sound is modulated by levels of task engagement in a visually presented short-term memory task. Task engagement was varied by manipulating the load involved in the encoding of the (visually presented) to-be-remembered items. Using a list of Navon letters (where a large letter is composed of smaller, different-identity letters), participants were oriented to attend and serially recall the list of large letters (low encoding load) or to attend and serially recall the list of small letters (high encoding load). Attentional capture by a single deviant noise burst within a task-irrelevant tone sequence (the deviation effect) was eliminated under high encoding load (Experiment 1). However, distraction from a continuously changing sequence of tones (the changing-state effect) was immune to the influence of load (Experiment 2). This dissociation in the amenability of the deviation effect and the changing-state effect to cognitive control supports a duplex-mechanism over a unitary-mechanism account of auditory distraction in which the deviation effect is due to attentional capture whereas the changing-state effect reflects direct interference between the processing of the sound and processes involved in the focal task. That the changing-state effect survives high encoding load also goes against an alternative explanation of the attenuation of the deviation effect under high load in terms of the depletion of a limited perceptual resource that would result in diminished auditory processing.

On the Neurocircuitry of Grasping: The influence of action intent on kinematic asymmetries in reach-to-grasp actions Abstract Evidence from electrophysiology suggests that nonhuman primates produce reach-to-grasp movements based on their functional end goal rather than on the biomechanical requirements of the movement. However, the invasiveness of direct-electrical stimulation and single-neuron recording largely precludes analogous investigations in humans. In this review, we present behavioural evidence in the form of kinematic analyses suggesting that the cortical circuits responsible for reach-to-grasp actions in humans are organized in a similar fashion. Grasp-to-eat movements are produced with significantly smaller and more precise maximum grip apertures (MGAs) than are grasp-to-place movements directed toward the same objects, despite near identical mechanical requirements of the two subsequent (i.e., grasp-to-eat and grasp-to-place) movements. Furthermore, the fact that this distinction is limited to right-handed movements suggests that the system governing reach-to-grasp movements is asymmetric. We contend that this asymmetry may be responsible, at least in part, for the preponderance of right-hand dominance among the global population.

Holistic word context does not influence holistic processing of artificial objects in an interleaved composite task Abstract Holistic processing, a hallmark of expert processing, has been shown for written words, signaled by the word composite effect, similar to the face composite effect: fluent readers find it difficult to focus on just one half of a written word while ignoring the other half, especially when the two word halves are aligned rather than misaligned. This effect is signaled by a significant interaction between alignment and congruency of the two word parts. Face and visual word recognition, however, involve different neural mechanisms with an opposite hemispheric lateralization. It is then possible that faces and words can both involve holistic processing in their own separate face and word processing systems, but by using different mechanisms. In the present study, we replicated with words a previous study done with faces (Richler, Bukach, & Gauthier, 2009, Experiment 3). In a first experiment we showed that in a composite task with aligned artificial objects, no congruency effects are found. In a second experiment, using an interleaved task, a congruency effect for Ziggerins was induced in trials in which a word was first encoded, but more strongly when it was aligned. However, in a stricter test, we found no differences between the congruency effect for Ziggerins induced by aligned words versus pseudowords. Our results demonstrate that different mechanisms can underlie holistic processing in different expertise domains.

How feature integration theory integrated cognitive psychology, neurophysiology, and psychophysics Abstract Anne Treisman’s Feature Integration Theory (FIT) is a landmark in cognitive psychology and vision research. While many have discussed how Treisman’s theory has fared since it was first proposed, it is less common to approach FIT from the other side in time: to examine what experimental findings, theoretical concepts, and ideas inspired it. The theory did not enter into a theoretical vacuum. Treisman’s ideas were inspired by a large literature on a number of topics within visual psychophysics, cognitive psychology, and visual neurophysiology. Several key ideas developed contemporaneously within these fields that inspired FIT, and the theory involved an attempt at integrating them. Our aim here was to highlight the conceptual problems, experimental findings, and theoretical positions that Treisman was responding to with her theory and that the theory was intended to explain. We review a large number of findings from the decades preceding the proposal of feature integration theory showing how the theory integrated many ideas that developed in parallel within neurophysiology, visual psychophysics, and cognitive psychology. Our conclusion is that FIT made sense of many preceding findings, integrating them in an elegant way within a single theoretical account.

Pitch-specific contributions of auditory imagery and auditory memory in vocal pitch imitation Abstract Vocal imitation guides both music and language development. Despite the developmental significance of this behavior, a sizable minority of individuals are inaccurate at vocal pitch imitation. Although previous research suggested that inaccurate pitch imitation results from deficient sensorimotor associations between pitch perception and vocal motor planning, the cognitive processes involved in sensorimotor translation are not clearly defined. In the present research, we investigated the roles of basic cognitive processes in the vocal imitation of pitch, as well as the degree to which these processes rely on pitch-specific resources. In the present study, participants completed a battery of pitch and verbal tasks to measure pitch perception, pitch and verbal auditory imagery, pitch and verbal auditory short-term memory, and pitch imitation ability. Information on participants’ music background was collected, as well. Pitch imagery, pitch short-term memory, pitch discrimination ability, and musical experience were unique predictors of pitch imitation ability. Furthermore, pitch imagery was a partial mediator of the relationship between pitch short-term memory and pitch imitation ability. These results indicate that vocal imitation recruits cognitive processes that rely on at least partially separate neural resources for pitch and verbal representations.

How to correctly put the “subsequent” in subsequent search miss errors Abstract Visual search, finding targets among distractors, is theoretically interesting and practically important as it involves many cognitive abilities and is vital for several critical industries (e.g., radiology, baggage screening). Unfortunately, search is especially error prone when more than one target is present in a display (a phenomenon termed the satisfaction of search effect or the subsequent search miss effect). The general effect is that observers are more likely to miss a second target if a first was already detected. Unpacking the underlying mechanisms requires two key aspects in analysis and design. First, to speak to the “subsequent” nature of the effect, the analyses must compare performance on single-target trials to performance for a second target in dual-target displays after a first has been found. Second, the design must include single-target displays that are matched in difficulty to each dual-target display to enable fair comparisons. However, it is not clear that prior research has met these two standards simultaneously. Work from academic radiology has primarily used designs with well-matched single- and dual-target trials, but most employed analyses that do not focus solely on performance after a first target has been detected. Work from cognitive psychology has generally performed the correct analyses, but relied on unmatched single- and dual-target trials, introducing a confound that could distort the results. In the current paper, we demonstrate the impact of this confound in empirical data and provide a roadmap for proper study design and analyses.

Medium versus difficult visual search: How a quantitative change in the functional visual field leads to a qualitative difference in performance Abstract The dominant theories of visual search assume that search is a process involving comparisons of individual items against a target description that is based on the properties of the target in isolation. Here, we present four experiments that demonstrate that this holds true only in difficult search. In medium search it seems that the relation between the target and neighbouring items is also part of the target description. We used two sets of oriented lines to construct the search items. The cardinal set contained horizontal and vertical lines, the diagonal set contained left diagonal and right diagonal lines. In all experiments, participants knew the identity of the target and the line set used to construct it. In difficult search this knowledge allowed performance to improve in displays where only half of the search items came from the same line set as the target (50% eligibility), relative to displays where all items did (100% eligibility). However, in medium search, performance was actually poorer for 50% eligibility, especially on target-absent trials. This opposite effect of ineligible items in medium search and difficult search is hard to reconcile with theories based on individual items. It is more in line with theories that conceive search as a sequence of fixations where the number of items processed during a fixation depends on the difficulty of the search task: When search is medium, multiple items are processed per fixation. But when search is difficult, only a single item is processed.

The second number-estimation elbow: Are visual numbers greater than 20 evaluated differently? Abstract Numerosity perception has long been understood to be divided between subitizing and estimation. In a series of three experiments (total N = 113), a new number “elbow” point in the estimation of visual number for numerosities of about 20 dots is confirmed. Below 20, mean estimates are linear with a slope of about 1 and power-function exponents for numerosity estimation approximate unity, though estimate variance increases dramatically above about 6 elements. For numerosities above 20, estimates become increasingly compressed, such that power function exponents are much lower (e.g., 0.7) and are lower still when both ranges are estimated within the same experimental procedure. The experiments described here show that the location of the inflection point appears insensitive to the range of numbers estimated and to differences in density.

Order versus chaos: The impact of structure on number-space associations Abstract The Spatial-Numerical Association of Response Codes (SNARC) effect has been observed with different stimuli, beside Arabic numerals, such as written/spoken number words, sequences of acoustic stimuli, and groups of elements. Here we investigated how the enumeration of sets of elements can be affected by the spatial configuration of the displayed stimuli with regard to the emergence of the SNARC effect. To this aim, we asked participants to perform a magnitude comparison task with structured (i.e., dice-like) and unstructured (i.e., random) patterns of rectangles. With this manipulation, we sought to explore the presence of the SNARC effect in relation to the structure of the displayed visual stimuli. The results showed that the spatial arrangement of rectangles does not impact visual enumeration processes leading to the SNARC effect. An unexpected reversal of the size effect for unstructured stimuli was also observed. We speculate that the presence of a similar SNARC effect, both with structured and unstructured stimuli, indicates the existence of a common access to the mental number line.