Carmel A. Levitan

Response to Comment on "Estimating the reproducibility of psychological science"

Gilbert et al. conclude that evidence from the Open Science Collaboration’s Reproducibility Project: Psychology indicates high reproducibility, given the study methodology. Their very optimistic assessment is limited by statistical misconceptions and by causal inferences from selectively interpreted, correlational data. Using the Reproducibility Project: Psychology data, both optimistic and pessimistic conclusions about reproducibility are possible, and neither are yet warranted.

Conducting perception research over the internet: a tutorial review.

This article provides an overview of the recent literature on the use of internet-based testing to address important questions in perception research. Our goal is to provide a starting point for the perception researcher who is keen on assessing this tool for their own research goals. Internet-based testing has several advantages over in-lab research, including the ability to reach a relatively broad set of participants and to quickly and inexpensively collect large amounts of empirical data, via services such as Amazon’s Mechanical Turk or Prolific Academic. In many cases, the quality of online data appears to match that collected in lab research. Generally-speaking, online participants tend to be more representative of the population at large than those recruited for lab based research. There are, though, some important caveats, when it comes to collecting data online. It is obviously much more difficult to control the exact parameters of stimulus presentation (such as display characteristics) with online research. There are also some thorny ethical elements that need to be considered by experimenters. Strengths and weaknesses of the online approach, relative to others, are highlighted, and recommendations made for those researchers who might be thinking about conducting their own studies using this increasingly-popular approach to research in the psychological sciences.

An expectations-based approach to explaining the cross-modal influence of color on orthonasal olfactory identification: The influence of the degree of discrepancy

In the present study, we explored the conditions under which color-generated expectations influence participants’ identification of flavored drinks. Four experiments were conducted in which the degree of discrepancy between the expected identity of a flavor (derived from the color of a drink) and the actual identity of the flavor (derived from orthonasal olfactory cues) was examined. Using a novel experimental approach that controlled for individual differences in color-flavor associations, we first measured the flavor expectations held by each individual and only then examined whether the same individual’s identification responses were influenced by his or her own expectations. Under conditions of low discrepancy, the perceived disparity between the expected and the actual flavor identities was small. When a particular color—identified by participants as one that generated a strong flavor expectation—was added to these drinks (as compared with when no such color was added), a significantly greater proportion of identification responses were consistent with this expectation. This held true even when participants were explicitly told that color would be an uninformative cue and were given as much time as desired to complete the task. By contrast, under conditions of high discrepancy, adding the same colors to the drinks no longer had the same effect on participants’ identification responses. Critically, there was a significant difference in the proportion of responses that were consistent with participants’ color-based expectations in conditions of low as compared with high discrepancy, indicating that the degree of discrepancy between an individual’s actual and expected experience can significantly affect the extent to which color influences judgments of flavor identity.

Cross-cultural color-odor associations

Colors and odors are associated; for instance, people typically match the smell of strawberries to the color pink or red. These associations are forms of crossmodal correspondences. Recently, there has been discussion about the extent to which these correspondences arise for structural reasons (i.e., an inherent mapping between color and odor), statistical reasons (i.e., covariance in experience), and/or semantically-mediated reasons (i.e., stemming from language). The present study probed this question by testing color-odor correspondences in 6 different cultural groups (Dutch, Netherlands-residing-Chinese, German, Malay, Malaysian-Chinese, and US residents), using the same set of 14 odors and asking participants to make congruent and incongruent color choices for each odor. We found consistent patterns in color choices for each odor within each culture, showing that participants were making non-random color-odor matches. We used representational dissimilarity analysis to probe for variations in the patterns of color-odor associations across cultures; we found that US and German participants had the most similar patterns of associations, followed by German and Malay participants. The largest group differences were between Malay and Netherlands-resident Chinese participants and between Dutch and Malaysian-Chinese participants. We conclude that culture plays a role in color-odor crossmodal associations, which likely arise, at least in part, through experience.

Red hot: the crossmodal effect of color intensity on perceived piquancy.

Color cues can influence the experience of flavor, both by influencing identification and perceived intensity of foods. Previous research has largely focused on the crossmodal influence of vision upon taste or olfactory cues. It is plausible that color cues could also affect perceived trigeminal sensation; these studies demonstrate a crossmodal influence of color on piquancy. In our first two experiments, participants rated the spiciness of images of salsas that were adjusted to vary in color and intensity. We found that red was associated with significantly higher ratings of expected spice than blue, and that darker reds were expected to be spicier than lighter reds. In our third experiment, participants tasted and then rated the spiciness of each of four salsas (with two levels of color and of piquancy) when sighted and when blindfolded. Spiciness ratings were unaffected by differing colors when the salsa was mild, but when the piquancy was increased, a lack of increase in color corresponded to a depressed spiciness. These results can be explained using a model of assimilation and contrast. Taken together, our findings show that in our US sample, there is a crossmodal correspondence between visual and trigeminal senses that can influence perception of spiciness.

Rate perception adapts across the senses: evidence for a unified timing mechanism

The brain constructs a representation of temporal properties of events, such as duration and frequency, but the underlying neural mechanisms are under debate. One open question is whether these mechanisms are unisensory or multisensory. Duration perception studies provide some evidence for a dissociation between auditory and visual timing mechanisms; however, we found active crossmodal interaction between audition and vision for rate perception, even when vision and audition were never stimulated together. After exposure to 5 Hz adaptors, people perceived subsequent test stimuli centered around 4 Hz to be slower, and the reverse after exposure to 3 Hz adaptors. This aftereffect occurred even when the adaptor and test were different modalities that were never presented together. When the discrepancy in rate between adaptor and test increased, the aftereffect was attenuated, indicating that the brain uses narrowly-tuned channels to process rate information. Our results indicate that human timing mechanisms for rate perception are not entirely segregated between modalities and have substantial implications for models of how the brain encodes temporal features. We propose a model of multisensory channels for rate perception, and consider the broader implications of such a model for how the brain encodes timing.

What's That Smell? An Ecological Approach to Understanding Preferences for Familiar Odors

How do odor preferences arise? Following Palmer and Schlosss (2010, PNAS, 107, 8877–8882) ecological valence theory of color preferences, we propose that preference for an odor is determined by preferences for all objects and/or entities associated with that odor. The present results showed that preferences for familiar odors were strongly predicted by average preferences for all things associated with the odors (eg people liked the apple odor which was associated with mostly positive things, such as apples, soap, and candy, but disliked the fish odor, which was associated with mostly negative things, such as dead fish, trash, and vomit). The odor WAVEs (weighted affective valence estimates) performed significantly better than one based on preference for only the namesake object (eg predicting preference for the apple odor based on preference for apples). These results suggest that preferences for familiar odors are based on a summary statistic, coding the valence of previous odor-related experiences. We discuss how this account of odor preferences is consistent with the idea that odor preferences exist to guide organisms to approach beneficial objects and situations and avoid harmful ones.

Encoding of Duration and Rate by an Integrative Model of Temporal Processing

Several models of temporal processing have been proposed in the empirical literature on time perception; all have been developed as models of a single temporal property, primarily event duration. We argue that there is ample reason to expand upon these models in order to include the processing of both rate and duration. We describe several ways that two popular timing models could handle rate, and illustrate that they would lead to different patterns of co-variation of rate and duration judgments. We review evidence that seemingly indicates discrepancies between the manner in which rate and duration are processed, and show that this evidence is problematic. A failure to carefully consider more global models has led to overly hasty arguments derived from empirical results suggesting a necessary dissociation between mechanisms of rate and duration. We argue instead that these findings place important constraints on how a global model might function, but do not rule out a common mechanism for rate and duration judgment.

Cross-modal temporal frequency channels for rate classification

We previously reported our discovery that temporal rate adaptation transfers bidirectionally between vision and audition. Temporal frequency channels are linked across audition and vision (Yao et al., 2009); but duration channels for audition and vision are thought to be independent (Heron et al., 2012). We used our paradigm to characterize linkages between auditory and visual channels by measuring whether or not transfer of adaptation still occurs as the discrepancy between adaptation and test frequencies increases. Participants ran in three experimental sessions, each with a different adaptation frequency. They were trained, using feedback, to classify flickering visual stimuli (ranging in frequency from 3.25–4.75 Hz) as fast or slow (relative to 4 Hz). They then classified 140 pre-adaptation test trials with feedback, providing a baseline. Afterwards, 30 adaptation trials of auditory stimuli beeping at either 5, 8, or 12 Hz were presented, followed by 20 alternating blocks of 7 adaptation and 7 post-adaptation test trials (without feedback). We compared the PSE of the pre- and post-adaptation trials to quantify the cross-modal transfer and found that the aftereffect occurred when the adaptation frequency was most similar to the test frequencies but was no longer present with larger discrepancies. These results rule out response bias as a plausible explanation for our original findings and suggest that the timing mechanisms underlying rate perception are consistent with supramodal channels that are tuned.

What you saw is what you will hear: Two new illusions with audiovisual postdictive effects

Neuroscience investigations are most often focused on the prediction of future perception or decisions based on prior brain states or stimulus presentations. However, the brain can also process information retroactively, such that later stimuli impact conscious percepts of the stimuli that have already occurred (called “postdiction”). Postdictive effects have thus far been mostly unimodal (such as apparent motion), and the models for postdiction have accordingly been limited to early sensory regions of one modality. We have discovered two related multimodal illusions in which audition instigates postdictive changes in visual perception. In the first illusion (called the “Illusory Audiovisual Rabbit”), the location of an illusory flash is influenced by an auditory beep-flash pair that follows the perceived illusory flash. In the second illusion (called the “Invisible Audiovisual Rabbit”), a beep-flash pair following a real flash suppresses the perception of the earlier flash. Thus, we showed experimentally that these two effects are influenced significantly by postdiction. The audiovisual rabbit illusions indicate that postdiction can bridge the senses, uncovering a relatively-neglected yet critical type of neural processing underlying perceptual awareness. Furthermore, these two new illusions broaden the Double Flash Illusion, in which a single real flash is doubled by two sounds. Whereas the double flash indicated that audition can create an illusory flash, these rabbit illusions expand audition’s influence on vision to the suppression of a real flash and the relocation of an illusory flash. These new additions to auditory-visual interactions indicate a spatio-temporally fine-tuned coupling of the senses to generate perception.