Muge Erol

Iconic memory is not a case of attention-free awareness.

Whether or not awareness entails attention is a much debated question. Since iconic memory has been generally assumed to be attention-free, it has been considered an important piece of evidence that it does not (Koch & Tsuchiya, 2007). Therefore the question of the role of attention in iconic memory matters. Recent evidence (Persuh, Genzer, & Melara, 2012), suggests that iconic memory does depend on attention. Because of the centrality of iconic memory to this debate, we looked again at the role of attention in iconic memory using a standard whole versus partial report task of letters in a 3×2 matrix. We manipulated attention to the array by coupling it with a second task that was either easy or hard and by manipulating the probability of which task was to be performed on any given trial. When attention was maximally diverted from the matrix, participants were able to report less than a single item, confirming the prior results and supporting the conclusion that iconic memory entails attention. It is not an instance of attention-free awareness.

Reply to Bachmann and Aru

A reply to the Bachmann and Aru (2015) critique of our paper (Mack, Erol, & Clarke, 2015) in which we rebut their criticisms and argue once again that our results support our view that iconic memory requires attention.

Scene incongruity and attention

Does scene incongruity, (a mismatch between scene gist and a semantically incongruent object), capture attention and lead to conscious perception? We explored this question using 4 different procedures: Inattention (Experiment 1), Scene description (Experiment 2), Change detection (Experiment 3), and Iconic Memory (Experiment 4). We found no differences between scene incongruity and scene congruity in Experiments 1, 2, and 4, although in Experiment 3 change detection was faster for scenes containing an incongruent object. We offer an explanation for why the change detection results differ from the results of the other three experiments. In all four experiments, participants invariably failed to report the incongruity and routinely mis-described it by normalizing the incongruent object. None of the results supports the claim that semantic incongruity within a scene invariably captures attention and provide strong evidence of the dominant role of scene gist in determining what is perceived.

Expectation Blindness: Seeing a face when there is none.

Taken together with our earlier reports, these findings are as convincing as behavioral data get, however they are not conclusive. The remaining question is whether, when observers report having seen the expected stimulus in its absence, they are actually hallucinating its presence (i.e. seeing it) or only inferring that the expected stimulus had been there. Current research in our lab is designed to try to answer this question. INTRODUCTION

Inattentional blindness to absent stimuli: the role of expectation

While this is the rst report of inattentional blindness to the absence of an expected stimulus and so testi es to the perceptual nature of the phenomenon and against inattentional amnesia, more importantly our results highlight the powerful role expectation can play in perception. We do not know for certain that those Os who reported seeing a circle on the critical trials when there was none, actually hallucinated a yellow or blue circle. If they did, this may be the rst report in which unhypnotised or undrugged observers see something that is not there solely because they had built up an expectation to see it.

Visual and semantic subliminal priming by two unrelated images

There is little question that single visual images can subliminally prime (Bar & Biederman, 1998) but the question of whether multiple, unrelated visual objects also can subliminally prime is not clear. Two experiments, explored whether subliminal presentations of two unrelated, visual objects would each independently prime. Experiment 1 (N=22) had 180 primed and 60 non-primed trials. On primed trials two black on white line drawings of familiar objects were presented left (image a) and right (image b) of fixation for 14 ms, backward masked, and followed by 2 visible test images. Observers reported whether the test images were the same or different. Response times (RT) were recorded. When the test items were the same, they were a-a or b-b. When different, they were the prime pair itself, (a-b). Each prime pair was shown three times as a target and 3 times as a prime. On non-primed trials a blank screen preceded the mask, which was followed by 2 not previously shown images, either the same or different. RTs in primed and non-primed trials were compared. The final condition, a visibility check consisted of 120 trials, 60 with and 60 without the subliminal original prime pairs and confirmed that primes were largely unidentifiable. On average, only 4 of the 120 flashed images, which by now had been shown 7 times, were identifiable. Priming was confirmed by the fact that RTs on primed trials were significantly faster than on non-primed trials in the same (p< .05) and different conditions (p< .05). Experiment 2 (N=22) asked whether the images primed semantically by exchanging the target images for single descriptive words. Otherwise the procedure was identical. We again found significant priming for same (p< .01) and different responses (p< .05). The combined results confirm that two unrelated, subliminal images can both visually and semantically prime. Meeting abstract presented at VSS 2015.

Two Object Subliminal Priming

Examples of priming stimuli Equipment The experiment was run on a 1.83 GHz Intel Core duo Mac Mini computer running OS10.5.8. It was programmed and run in Superlab 4.0.7. The display appeared on a Mitsubishi DPlus74SB CRT monitor, 75Hz, 1152x864 dpi. Research Question Previous research has investigated the extent to which visual images of objects that are not consciously perceived are encoded and prime. Bar and Biederman (1998), for example, using a subliminal priming paradigm, found that sub-threshold presentations of single objects do indeed affect performance on subsequent tasks. We asked whether subliminal presentations of two visual images would both be able to prime subsequent responses, something that has not been demonstrated previously. This question bears on the issue of how much and to what extent information is processed and encoded outside of awareness. We hypothesized that subjects’ responses to a speeded same/different decision task would be quicker if one of the two visual test objects previously had been presented subliminally.