Recent HCI research has looked at conveying emotions through non-visual modalities, such as vibrotactile and thermal feedback. However, emotion is primarily conveyed through visual signals, and so this research aims to support the design of emotional visual feedback. We adapt and extend the design of the "pulsing amoeba" [29], and measure the emotion conveyed through the abstract visual designs. It is a first step towards more holistic multimodal affective feedback combining visual, auditory and tactile stimuli. An online survey garnered valence and arousal ratings of 32 stimuli that varied in colour, contour, pulse size and pulse speed. The results support previous research but also provide new findings and highlight the effects of each individual visual parameter on perceived emotion. We present a mapping of all stimulus combinations onto the common two-dimensional valence-arousal model of emotion.