What do sensory scales measure?

It is indeed an honour to have drawn Professor Stevens' fire (1964), in view of the magnitude of his research achievement in the field of sensory scaling. If I shall differ with him on certain of his conclusions, it is in full awareness of the debt we all owe him for the experimentation and thinking which has provided much of the factual basis and theoretical stimulus to further research and development in this area.

Professor Stevens (1960, 1964) advocates a psychophysical power law, while I have questioned it (Treisman, 1961, 1962, 1963a, 1963b, 1964a). I shall here examine the main points of disagreement lying behind these differing positions.     

Dyslexia: sensory deficits or inattention?

An important question in regard to dyslexia is whether or not this condition is the result of sensory deficits. A number of studies have indeed found sensory deficiencies in dyslexic readers. However, it has been proposed that these are due simply to inattention. If so, this would be expected to produce either (i) a general reduction or (ii) random reductions in performance. On the basis of published data, it seems that neither of these is in fact the case. Rather the data indicate reproducible non-random patterns of deficiencies with regard to stimulus conditions. The stimulus specificity of the deficits represents, therefore, an important issue which needs to be addressed by any attempt to account for the sensory deficiencies of dyslexic readers in terms of inattention.     

Are olfactory images sensory in nature?

We investigated the features of olfactory mental images by comparing odour images with perceptual and semantic representations. Participants who were assigned to three groups made similarity judgments about 17 common odours by smelling odours, imagining odours, or on the basis of the meaning of odour source names. In the smelling group, every pair of odours was compared. In the imagining group, imagined odours were compared twice, both before and after associative learning of the odour/name combinations. In the meaning group, the odour source names were compared in terms of general word meanings. Nonmetric multidimensional scaling analysis was applied to each group of similarity data and three-dimensional sensory, mental, and semantic spaces were composed. 17 elements in the mental and semantic spaces were superimposed onto the sensory space by Procrustes rotation. We found that the averaged distances of the 17 elements between the sensory and the mental spaces (either before or after learning) were smaller than those between the sensory and semantic spaces. We suggest that odour images have sensory features, especially after associative learning between perceived odours and their names.     

How inherently noisy is human sensory processing?

Like any physical information processing device, the human brain is inherently noisy: If a participant is presented with the same sensory stimulus multiple times and is asked to press one of two buttons in response to some property of the stimulus, the response may vary even though the stimulus did not. This response variability can be used to estimate the amount of so-called internal noise—that is, noise that is not present in the stimulus (such as random dynamic dots on the screen) but in the participant’s brain. How large is this internally generated noise? We obtained >400 independent estimates on 40 participants for a range of protocols (yes/no, two-, four-, and eight-alternative forced choice), modalities (auditory and visual), attentional state, adaptation state, stimulus types (static, moving, stereoscopic), and other parameters (timing, size, contrast). Our final estimate at ～1.3 (units of external noise standard deviation) is generally somewhat larger than that previously inferred from smaller and less varied data sets. We discuss the impact of high levels of internal noise on a number of experimental and computational efforts aimed at understanding and characterizing human sensory processing.     

Risk-induced neophobia: does sensory modality matter?

Recent studies have documented that exposure to high levels of background risk can induce neophobic predator avoidance in prey animals, whereby they respond to any novel cue with an anti-predator response. Such phenotypically plastic predator avoidance may allow prey to maximize anti-predator benefits in variable risk environments. It remains poorly understood whether risk assessment information from different sensory modalities can be integrated to induce generalized, cross-sensory system neophobic responses. Here, we directly test this hypothesis by exposing juvenile convict cichlids (Amatitlania nigrofasciata) to high- versus low-risk environments using either conspecific alarm cue (chemosensory risk) or a model avian predator (visual/mechanical risk) and testing their response to a novel chemosensory cue (Experiment 1) or visual cue (Experiment 2). Our results suggest that regardless of the sensory modality used to increased perceived risk, cichlids pre-exposed to high-risk conditions exhibited increased predator avoidance in response to any novel visual or chemical cue. As expected, cichlids pre-exposed to low-risk conditions did not display any neophobic responses. Our results suggest that induced neophobia is not cue specific; rather, it may function as a generalized response to perceived predation risk.     

Can attention be allocated to sensory modalities?

Three experiments examined the effects of attention allocation to the modalities of vision, audition, and touch. The first two experiments utilized a simultaneous-successive comparison. The simultaneous procedure involved simultaneous monitoring of all three sensory modalities for the presence of a near-threshold stimulus. The successive condition allowed S to give his full attention to each sensory modality in turn. There was no advantage for the successive condition, whether the task consisted of detection of a single stimulus (Experiment I) or detection of the absence of one of many stimuli (Experiment II). Experiment III used a different paradigm to extend these results and bridge the gap between these results, those of Eijkman and Vendrik (1965), and those of Moray (1973a, b). We concluded that selective allocation of attention to sensory modalities does not affect the early stages of perceptual processing.     

Dynamic sensory–motor oscillation and cerebral development

Drawing from Freud’s Project, the author proposes a model of cerebral development whose sensory–motor structure is defined by a frontal–occipital oscillatory dynamic with a twofold function: the oscillation explains the formation and maintenance of mother–infant attunement in cerebral growth, while, at the same time, also explaining the functioning of the projective–introjective dynamic at the basis of psychoanalytic theory. The oscillatory dynamic, according to this perspective, operates as a “bridge” between two seminal theoretical models of developments—the psychoanalytic and the infant research model—which, in turn, leads to the formulation of some neurological hypotheses on how oscillation regulates the elaboration of maternal interaction in the infant’s brain, and how the mother may act to modify it. The paper discusses how the oscillatory dynamic offers an innovative framework for the reconceptualization of the development of mentalization, the function of mirror neurons, and, most interestingly, of the development of language, explaining the non-verbal properties of ordinary linguistic communication and the function of oscillation in the regulation of information exchange processing.     

Object-based attention: sensory modulation or priority setting?

The detection of an invalidly cued target is faster when it appears within a cued object than when it appears in an uncued object equally distant from the cued location; this is a manifestation of object based attention. Five experiments are reported in which it was investigated whether early sensory enhancement (in which attention "spreads" within an attended object but stops at its borders) or a later attentional prioritization mechanism best accounts for these effects. In Experiments 1-4, subjects identified a centrally located target with a buttonpress while attempting to ignore flanking distractors that were mapped to either a compatible or an incompatible response. The flankers appeared either within the object occupied by the target or in a different object but at the same distance from the target. The well-known effect of distance between the target and the flankers on the magnitude of the compatibility effect was replicated. However, whether the target and the flankers were in the same or different objects had no effect on the magnitude of the compatibility effect. In Experiment 5, when attention could not be narrowly focused in advance, object-based modulation of the flanker effect was observed. These results suggest that object-based selection may reflect an object-specific attentional prioritization strategy, rather than object-based attentional modulation of an early sensory representation.     

Is sensory processing an issue for infants with colic?

ObjectivesTo determine the association between sensory functioning, sleep, cry/fuss, and feeding behaviors of infants with colic younger than 4 months of age.MethodsDunn’s Infant/Toddler Sensory Profile™ and a modified Barr Baby Day Diary^© were used to assess 44 breastfed infants with colic under four months of age. Colic was defined according to Wessel’s criteria.ResultsThirty-four of the 44 infants with colic (77%) scored as atypical for sensory processing. Of these, 56% scored atypical for sensory processing on quadrant one (Q1) (Low Registration), with 24%, 65%, and 18% scoring as atypical for sensory processing on Q2 (Sensory seeking), Q3 (Sensory sensitivity), and Q4 (Sensation avoiding), respectively. All infants demonstrating sensation avoiding also scored as Low Threshold. A moderate statistically significant correlation was found between sensation seeking and time spent sleeping (r = 0.31; p = 0.04). No other statistically significant associations between infant behaviors and their sensory functioning were demonstrated. Overall, infants demonstrating atypical sensory responses (in any quadrant) slept significantly more than infants demonstrating typical sensory responses (mean difference = −67.8 min/day; 95% CI = −133.6 to −2.1; p = 0.04).ConclusionVery limited associations between infant behaviors and sensory functioning were demonstrated, suggesting that sensory functioning may not be a significant factor in the multifactorial nature of infant colic. Further well-designed studies using validated tools for infants with colic are required to determine whether associations between infant behaviors and sensory functioning exist.     

A statistical decision model for sensory discrimination which predicts Weber’s law and other sensory laws: Some results of a computer simulation

A model for visual intensity threshold discrimination is described. Simplified assumptions represent the main features of the visual afferent paths. Discriminative responses are selected centrally by a statistical decision procedure, limited by the noise level. Noise arises from the irreducible physical variability of light, from spontaneous firing, and from variations in transmission in the afferent paths. These variations will tend to be positively correlated, The model was simulated on a computer: it correctly predicts the form of the Weber function (the relation between difference threshold and background intensity) and the features of spatial and temporal “summation”, It also shows that the function relating the eentral effeet of a stimulus to its physical intensity is unlikely to be logarithmic or a power function with a small exponent.     

Does temporal preparation increase the rate of sensory information accumulation?

Recent studies showed that temporal preparation, i.e., the ability to prepare for an upcoming stimulus, improves perceptual processing. The mechanisms underlying this benefit are still controversial. Based upon the theoretical framework of accumulation models, it has been proposed that the accumulation of sensory stimulus information begins earlier when participants are temporally prepared than when they are unprepared. Alternatively, however, temporal preparation might also affect the accumulation rate of sensory information. In the present study, we examined these possibilities. Specifically, in three experiments, we manipulated participants' decision criterion. This manipulation should interact with any experimental manipulation affecting the rate of information processing, but produce additive effects with any manipulation affecting the onset of information accumulation rather than its rate. We obtained additive effects on RT, irrespective of whether the decision criterion was manipulated by increasing catch trial proportion or nogo trial proportion. These results suggest that temporal preparation improves perceptual processing by operating on the onset of sensory information accumulation rather than the rate of sensory information accumulation.     

Dual-task automatization: The key role of sensory–motor modality compatibility

How do people automatize their dual-task performance through bottleneck bypassing (i.e., accomplish parallel processing of the central stages of two tasks)? In the present work we addressed this question, evaluating the impact of sensory–motor modality compatibility—the similarity in modality between the stimulus and the consequences of the response. We hypothesized that incompatible sensory–motor modalities (e.g., visual–vocal) create conflicts within modality-specific working memory subsystems, and therefore predicted that tasks producing such conflicts would be performed less automatically after practice. To probe for automaticity, we used a transfer psychological refractory period (PRP) procedure: Participants were first trained on a visual task (Exp. 1) or an auditory task (Exp. 2) by itself, which was later presented as Task 2, along with an unpracticed Task 1. The Task 1–Task 2 sensory–motor modality pairings were either compatible (visual–manual and auditory–vocal) or incompatible (visual–vocal and auditory–manual). In both experiments we found converging indicators of bottleneck bypassing (small dual-task interference and a high rate of response reversals) for compatible sensory–motor modalities, but indicators of bottlenecking (large dual-task interference and few response reversals) for incompatible sensory–motor modalities. Relatedly, the proportion of individuals able to bypass the bottleneck was high for compatible modalities but very low for incompatible modalities. We propose that dual-task automatization is within reach when the tasks rely on codes that do not compete within a working memory subsystem.

     

Matching auditory and visual signals: is sensory modality just another feature?

In order to perceive the world coherently, we need to integrate features of objects and events that are presented to our senses. Here we investigated the temporal limit of integration in unimodal visual and auditory as well as crossmodal auditory-visual conditions. Participants were presented with alternating visual and auditory stimuli and were asked to match them either within or between modalities. At alternation rates of about 4 Hz and higher, participants were no longer able to match visual and auditory stimuli across modalities correctly, while matching within either modality showed higher temporal limits. Manipulating different temporal stimulus characteristics (stimulus offsets and/or auditory-visual SOAs) did not change performance. Interestingly, the difference in temporal limits between crossmodal and unimodal conditions appears strikingly similar to temporal limit differences between unimodal conditions when additional features have to be integrated. We suggest that adding a modality across which sensory input is integrated has the same effect as adding an extra feature to be integrated within a single modality.     

Seeing with sound? exploring different characteristics of a visual-to-auditory sensory substitution device

Sensory substitution devices convert live visual images into auditory signals, for example with a web camera (to record the images), a computer (to perform the conversion) and headphones (to listen to the sounds). In a series of three experiments, the performance of one such device ('The vOICe') was assessed under various conditions on blindfolded sighted participants. The main task that we used involved identifying and locating objects placed on a table by holding a webcam (like a flashlight) or wearing it on the head (like a miner's light). Identifying objects on a table was easier with a hand-held device, but locating the objects was easier with a head-mounted device. Brightness converted into loudness was less effective than the reverse contrast (dark being loud), suggesting that performance under these conditions (natural indoor lighting, novice users) is related more to the properties of the auditory signal (ie the amount of noise in it) than the cross-modal association between loudness and brightness. Individual differences in musical memory (detecting pitch changes in two sequences of notes) was related to the time taken to identify or recognise objects, but individual differences in self-reported vividness of visual imagery did not reliably predict performance across the experiments. In general, the results suggest that the auditory characteristics of the device may be more important for initial learning than visual associations.     

Auditory sensory gating and performance on the Delis–Kaplan Executive Function System

Sensory gating is a neurological mechanism that inhibits redundant sensory information. Impaired sensory gating is not uncommon in otherwise healthy individuals, but its relationship with higher level cognitive function is poorly understood. It is plausible that cognitive fragmentation associated with poor sensory gating may affect an individual's higher level executive functioning. Fifty-one participants (Mean age?=?22.02; 24 males) were administered an electroencephalogram with a paired-tone paradigm to measure sensory gating as well as a comprehensive executive functioning battery—the Delis–Kaplan Executive Function System. Overall, better performance on the D-KEFS was related to more effective sensory gating. Also, tasks that measured cognitive flexibility predicted P50 latency as well as P200 amplitude and sensory gating. Understanding the relationship between sensory gating and cognitive processing has implications for healthy individuals and clinical groups alike.     

Understanding or feeling? Motor and sensory processes in recall of haptic experiences

Effects of learning can show in a direct, i.e., explicit way, or they can be expressed indirectly, i.e., in an implicit way. It is investigated whether hepatic information shows implicit effect, and whether implicit haptic memory effects are based primarily on motor or on sensory memory components. In the first phase blindfolded subjects had to palpate objects in order to answer questions about the objects' distinct properties as fast as possible. In the following phase this task was repeated with the same objects and additional control items. Additionally, recognition judgements were required. Results demonstrate reliable effects of implicit memory for haptic information in terms of reaction times to old vs. new objects. Subjects who had to wear plastic gloves in the first stage showed comparable effects of repetition priming. Changing the questions--and, thus, hand movements--during the palpitation of objects known from the first stage, however, abolishes implicit memory expression. It is concluded, therefore, that implicit memory for haptic information is based on motor processes. On the other hand, explicit memory is hampered in subjects wearing gloves during the first phase, as revealed in terms of recognition performance while changing the questions about objects' properties has no effect on recognition judgements. Thus, explicit memory for haptic information seems to be based on the sensory processes when touching objects.     

Are age-related changes in cognitive function driven by age-related changes in sensory processing?

Although there has been keen interest in the association among measures of sensory function and cognitive function for many years, in general, measures of sensory function have been confined to one or two senses and measures of threshold sensitivity (acuity). In this study, rigorous psychophysical measures of threshold sensitivity, temporal gap detection, temporal order identification, and temporal masking have been obtained, in hearing, vision, and touch. In addition, all subjects completed 15 subtests of the Wechsler Adult Intelligence Scale, 3rd edition (WAIS–III). Data were obtained from 245 adults (18–87 years old) for the WAIS–III and for 40 measures of threshold sensitivity and temporal processing. The focus in this report is on individual differences in performance for the entire data set. Principal-components (PC) factor analysis reduced the 40 psychophysical measures to eight correlated factors, which were reduced further to a single global sensory processing factor. Similarly, PC factor analysis of the 15 WAIS–III scores resulted in three correlated factors that were further reduced to a single global cognitive function factor. Age, global sensory processing, and global cognitive function were all moderately and significantly correlated with one another. However, paired partial correlations, controlling for the third of these three measures, revealed that the moderate correlation between age and global cognitive function went to zero when global sensory processing was controlled for; the other two partial correlations remained intact. Structural models confirmed this result. These analyses suggest that the long-standing observation of age-related changes in cognitive function may be mediated by age-related changes in global sensory processing.     

The sensory match effect in recognition memory: Perceptual fluency or episodic trace?

The sensory match effect in recognition memory refers to the finding that recognition is better when the sensory form in which an item is tested is the same as that in which it was studied. This paper examines the basis for the sensory match effect by manipulating whether a studied fragmented picture is tested with the same or a complementary set of fragments in a recognition memory test (Experiment 1) and in a fragment-identification test (Experiment 2). Assuming that fragment identification is a direct measure of perceptual fluency, we expected identical patterns of results across the two tests if perceptual fluency accounted for the sensory match effect in recognition memory. Instead, recognition memory showed a robust overall sensory match effect (the same fragmented image was recognized better than the complementary image), whereas fragment identification showed no overall sensory match effect (the same fragmented image was identified no better than the complementary fragmented image). Experiments 3 and 4 combined the two responses and showed that the basis for the sensory match effect in recognition memory was a subject’s ability to recognize the matching fragments in the absence of conceptual information (when the test stimulus could not be identified), supporting the idea that the episodic trace of the sensory code is responsible for the sensory match effect in recognition memory. Experiment 5 demonstrated that subjects are able to use this sensory code as the sole basis for recognition memory.